Past Seminars

2022-09-21 11:00:00

Dominik Rattenbacher Max Planck Institute for the Science of Light, Staudtstraße 2, 91058 Erlangen, Germany

On-Chip Quantum Optics and Sensing with Organic Molecules

In my talk I will introduce polycyclic aromatic dye molecules as two-level quantum emitters and will review the recent advances of our group in controlling and manipulating their light-matter interaction by shaping their nanoenviroment. A special focus will be given on my PhD work dealing with the coupling of organic molecules to chip-based nanophotonic circuits. Here, I will discuss the coupling of individual molecules to one-dimensional subwavelength waveguides and the prospects of realizing coupled emitter ensembles by DC-Stark tuning of the molecular resonances. Furthermore, I will demonstrate that the sensitivity of the molecules to electric fields can be used to sense fields in their nanoenviroment. The specific example will be weak charge fluctuations in a gallium phosphide waveguide. I will present a series of experiments that reveal the spatial and temporal correlations of the electric field and show that the temporal correlation scales proportionally with the optical intensity. In the quest for reaching near deterministic coupling efficiencies, I will introduce ring- and disc-resonators and show the Purcell-enhanced coupling of single molecules to these structures. With our most recent design, a 6 µm diameter disk resonator, I will demonstrate a resonator finesse up to 250 (Q=16000), leading to coupling efficiency of 75%. Furthermore, I will show the controlled manipulation and tuning of molecular resonances via nearby microelectrodes and the simultaneous coupling of two individual molecules to the two counter propagating modes of the disc.

Speaker's Bio

Dominik Rattenbacher studied physics in the "Physics Advanced Program" at the Universities of Erlangen and Regensburg from 2013 to 2018. After a research stay at the Ultrafast and Attosecond Science group of Prof. Hans Jakob Wörner at ETH Zurich, he did his Master thesis on "Spectroscopic investigation of two molecules coupled via a dielectric waveguide" in the Division of Vahid Sandoghdar at the Max Planck Institute for the Science of Light. His PhD work is a direct continuation of this project and aims at coupling several molecules efficiently via nanophotonic circuits.

2022-09-14 11:00:00

Burak Gurlek Max Planck Institute for the Science of Light

Engineering Long-Lived Molecular Vibrational States and Light-Matter Interactions

Single organic molecules in the solid-state are one of the promising optical platforms for realizing quantum networks owing to their remarkable coherent properties and flexibility in their chemical synthesis [1]. Specifically, their Fourier-limited zero-phonon line transitions at liquid helium temperatures provide bright single-photons and nonlinear interactions at the few-photon levels. However, the molecular excited states typically decay in the order of nanoseconds. This limits quantum coherence in these systems and emission rate of single photons, posing a challenge for practical applications in quantum technologies. In the first part of this talk, I will focus on the inherent optomechanical character of organic molecules in the solid-state for achieving long-lived quantum coherence in these systems. I will present a scheme consists of a single organic molecule in host matrix with a structured phononic environment [2]. By suppressing phononic decay channels, we realize and exploit long optomechanical coherence times up to milliseconds for storing and retrieving information. I will demonstrate that the resulting long-lived vibrational states facilitate reaching the strong optomechanical regime at the single photon level. In the second part, I will address light-matter interaction of a quantum emitter. It is a common practice to use cavities or plasmonic nanoantennas to increase light-matter interaction via Purcell effect. I will show that by hybridizing those two systems, the emission rate of an emitter can be enhanced with respect to the individual systems [3]. More importantly, the resulting cavity-induced radiative coupling can dominate the nonradiative channels in the near field of the plasmonic nanoantenna. I will further discuss the promise of reaching single-molecule strong coupling regime by using the proposed hybrid photonic structure. Lastly, I will show how to translate similar ideas to magnetic light-matter interactions by using atomic arrays [4]. Our results pave the way of molecular quantum networks, bright single photon sources, coherent light-matter interactions and quantum optomechanical applications with molecules. 1. C. Toninelli et al., Nat. Mater. 20, 1615–1628 (2021). 2. B. Gurlek et al., Phys. Rev. Lett. 127, 123603 (2021). 3. B. Gurlek et al, ACS Photonics 5, 456 (2018). 4. R. Alaee et al., Phys. Rev. Lett. 125, 063601 (2020).

Speaker's Bio

Burak Gurlek obtained his B.Sc. degree both in Telecommunication Engineering and Mathematics with summa cum laude from the Istanbul Technical University. He then moved to Polytechnique Montreal to work on non-reciprocal metamaterials for his master thesis. He is currently a Ph.D. student in the group of Prof. Vahid Sandoghdar at the Max Planck Institute for the Science of Light. He won numerous awards including Ord. Prof. Bedri Karafakioglu award from the Istanbul Technical University. In his Ph.D., Burak worked on hybrid cavity-nanoantenna systems for coherent light-matter interfaces and theory of single molecule spectroscopy. His work also focuses on improving optomechanical qualities of single organic molecules for quantum information. His current research interests lie in molecular quantum optics, engineering molecular interactions, atomic arrays and artificial scientific discovery.

2022-08-31 11:00:00

Camille Papon Niels Bohr Institute, University of Copenhagen

Circuit-based resonant excitation of multiple quantum dots

Single photons and their interaction with quantum emitters are key components of quantum information protocols, finding applications in quantum communication and quantum simulation. Self-assembled InAs quantum dots (QDs) embedded in pin-GaAs membrane present excellent optical properties, and their integration within planar photonic nanostructures ensures near-deterministic light-matter interaction. Further scaling of this platform requires an efficient strategy to operate multiple single-photon sources (SPS) simultaneously. In this talk, we will present a way to tackle this challenge by demonstrating the scalable operation of multiple SPSs using a specially designed nanophotonic circuit. We realize simultaneous resonant excitation of two QDs positioned in separate dual-mode waveguides and demonstrate their independent Stark tuning with electrical biases. The low-noise properties of QDs together with the individual control of their energy is highlighted by two-photon quantum interference measurement. This work promotes the fully waveguide-based approach towards the scalable operation of deterministic SPSs for various quantum information application. The realized strategy can be applied to other quantum nanophotonic platforms.

Speaker's Bio

I’m currently a PhD student in the Quantum Photonics group at the Niels Bohr Institute, in Copenhagen. During my 3-years research, I put my effort in expanding the scalability of the planar quantum photonic platform towards direct quantum information applications. This builds up on my prior Msc. project, focused on the nanofabrication and characterization of on-chip single-photon router based on nano-electro-mechanical switches, followed by one-year research assistant position, dedicated to outcoupling and efficiency of planar nanostructures.

2022-08-30 11:00:00

Qiushi Gu Cavendish Laboratory, University of Cambridge

Optically addressable spins in nanodiamonds and hexagonal boron nitride for quantum sensing and communication

Spin qubits in solid-state systems are strong contenders for quantum communication, computation and metrology. In this seminar I will introduce two such systems I have studied and their application in room-temperature quantum sensing and spin-photon interfaces. Temperature plays a critical role in all chemical reactions in cells and understanding intracellular temperature variations is crucial for biochemical energetics. In addition, rheology is an integral part of cell morphology, division and transport. It is actively regulated by cells in response to temperature. Despite its importance, intracellular thermometry remains challenging, often obscured by the noise due to local biochemical environments. In the first part of the talk, I will illustrate the dual modal quantum sensor based on NV centres in nanodiamonds, which are capable of simultaneously sensing nanoscale temperature and rheology in viscoelastic fluids and a dynamic cellular environment. This technique offers new avenues for understanding intracellular energetics. Next, I will focus on optically addressable single spin defects in two-dimensional (2d) hexagonal boron nitride (hBN). Spin defects in 2d layered materials offer advantages over their bulk counterparts, as their reduced dimensionality enables more feasible on-chip integration into devices. I will report the first room-temperature optically detected magnetic resonance (ODMR) from single carbon-related defects in hexagonal boron nitride. I will show that either positive or negative ODMR signal is observed for each defect. Based on kinematic models, we relate this bipolarity to highly tuneable internal optical rates. In addition, we resolve an ODMR fine structure in the form of an angle-dependent doublet resonance, indicative of weak but finite zero-field splitting. Our results offer a promising route towards realising a room-temperature spin-photon quantum interface in hexagonal boron nitride.

Speaker's Bio

Dr Qiushi Gu received his BA and MSci degrees from the University of Cambridge, UK. He subsequently joined Mete Atature’s group and obtained his PhD in Physics degree in 2022. His work focuses on using spin manipulation techniques for quantum sensing and information processing. Gu worked with NV centres in nanodiamonds for nanoscale NMR experiments and intracellular temperature and rheology sensing. He also identified the first room-temperature ODMR signatures for single spins in hexagonal boron nitride. His research interest lies in optically addressable quantum systems and their manipulation.

2022-08-24 11:00:00

Nima Taghipour ICFO – The Institute of Photonic Sciences

Colloidal Quantum Dot Lasers: from the Visible to the Infrared

Colloidal semiconductor quantum dots (CQDs) have been considered as a promising material platform for the realization of solution-processed lasers. In addition to wide range spectral tunability thanks to quantum confinement, CQDs offer other interesting properties for lasing applications including atomic-like discrete energy levels and chemical stability, making them compatible with any arbitrary substrate and optical cavities [1]. However, CQD-lasers have suffered severely from poor gain performances, making them impractical for feasible daily-life applications. The fundamental limitations of the CQDs as a gain medium arise from non-unity degeneracy of the band-edge state [1]. Then, to achieve light amplification, at least some of the CQDs must contain more than one exciton. An additional complication is associated with nonradiative Auger recombination, whereby the electron–hole recombination energy is transferred to a third carrier. This results in Therefore, the low-threshold CQD-lasers at room temperature are essentially needed. In the first part of the talk, I will discuss about the infrared lasers based on Pb-chalcogenide CQDs. Room-temperature tunable emission infrared lasers are achieved by integrating Pb CQDs to the distributed feedback cavity (DFB) [2]. By engineering the Auger process in PbS CQDs at the supra-nanocrystalline level, we achieved low threshold highly stable single-mode infrared DFB-laser [3]. Our recent result show that using heterostructured Pb-chalcogenide core/shell CQDs allows us to achieve sub-single-exciton laser for the first time in an infrared CQD materials [4]. Additionally, I will talk about our dual functional device which operates as infrared light emitting diode and laser under electrical- and optical-excitation, respectively [5]. In the second part of my talk, I will present my research activities in realization of highly-efficient visible-emitting CQD-lasers. In doing so, we have designed and developed a heterostructure of CdSe-based CQDs, which led us to achieve record lowest gain/lasing threshold among all semiconductor nanocrystals [6]. Additionally, we showed red-emitting multi-mode lasers which obtained by coupling these engineered CQDs heterostructure to a core-less optical fiber, in which lasing modes supported by whispering-gallery-mode resonator [7]. References: 1. Y. Park et al., Nature review materials, 6, 382–401 (2021) 2. G. L. Whitworth et al., Nature Photonics , 15, 738-742 (2021) 3. N. Taghipour et al., Advanced Materials 34 (3), 2107532 (2022) 4. N. Taghipour et al., under review 5. N. Taghipour et al., Advanced Functional Materials, 220832 (2022) 6. N. Taghipour et al. Nature Communication, 11, 3305 (2020) 7. M. Sak, N. Taghipour et al., Advanced Functional Materials, 3, 1907417 (2020)

Speaker's Bio

Nima Taghipour is a PREBIST Marie Curie Ph.D. fellow at ICFO-Institute of Photonics Sciences, working in Functional Optoelectronics Nanomaterials under the supervision of professor Gerasimos Konstantatos. Prior to joining ICFO, Nima worked in UNAM-National Nanotechnology Center in the Quantum Devices and Sensors group as a postgraduate researcher at Bilkent University, Turkey. He received his B.Sc. in Electronics Engineering and his M.Sc. in Photonics Engineering in the same department at Tabriz university, Iran. Nima's research is understanding excitonic properties of low-dimensional quantum confined materials including colloidal semiconductor quantum -dots, -wells and two-dimensional semiconductors. He uses these nanomaterials to develop novel light-detection and light-emitting devices especially lasers. After being awarded the COFUND PREBIST Ph.D. fellowship under the Marie-Curie action on a proposal entitled “Optical Gain and Lasing in Infrared Colloidal Quantum Dots”, he joined ICFO to pursue his Ph.D. degree. His current research focuses on the lasing action of colloidal semiconductor quantum dot (CQDs) in the telecommunication band. The objective of his Ph.D. study is the demonstration of highly-performed infrared lasers based on CQDs.

2022-08-17 11:00:00

Owen Miller Yale University

Physical design meets convex optimization: Hidden structure in Maxwell's and Schrodinger's equations

In optimization theory, one clear dividing line between "easy" and "hard" problems is convexity. Convex optimization problems do not have local optima that are not global optima, and multiple decades of development have led to efficient computational machinery for solving convex problems. By contrast, nonconvex problems can have highly oscillatory landscapes, and one must typically use local optimization techniques or black-box algorithms. Nanophotonic design problems, and many design problems across physics, reside squarely in the latter category of nonconvex optimization problems. Or do they? I will show that there is a surprising amount of mathematical structure hidden in the typical differential equations of physics, and that this structure enables new connections to modern techniques in convex optimization. I will describe how the key constraints in these design problems can be transformed from the typical differential-equation descriptions to infinite sets of local conservation laws, and that the latter have a structure amenable to quadratic and semidefinite programming. I describe how this approach can lead to global bounds ("fundamental limits") for many design problems of interest, and potentially to dramatically new approaches to identifying designs themselves. Next, specific to electromagnetic scattering, I will describe a unique construction of scattering matrices that leads to new methods for identifying fundamental limits across any bandwidth of interest. Throughout I will emphasize novel applications where we have applied these techniques, including: minimal-thickness perfect absorbers, scaling laws for analog photonics, speed limits in quantum optimal control, and a new theory of the ultimate limits of near-field radiative heat transfer.

Speaker's Bio

Owen Miller is an Asst. Prof. of Applied Physics and Physics at Yale. His research interests center around developing large-scale computational and analytical design techniques for discovering novel structures and new phenomena in nanophotonics. He is the recipient of AFOSR and DARPA young investigator awards, as well as the Yale Graduate Mentor award.

2022-07-27 11:00:00

Michael R Grace University of Arizona

Quantum Limits and Optimal Receivers for Passive Sub-Diffraction Imaging

Does quantum mechanics have anything useful to contribute to technology development in high-precision classical sensing? For quantitative sensing tasks in many application spaces, modeling the light collected by an optical sensor as a quantum state is a powerful theoretical avenue for evaluating how precisely the task could be carried out if the sensor is allowed to make any measurements that obey the laws of physics. Focusing on far-field super-resolution imaging, I will discuss how such a quantum information-theoretic framework has led us at the University of Arizona and others to develop "quantum-inspired" techniques that provably approach or achieve the upper limits on imaging precision that nature allows (such as the quantum Cramer-Rao bound on parameter estimation or the quantum Chernoff bound on object discrimination) while yielding large fundamental improvements over conventional resolution limits. I will highlight our theoretical and experimental progress in pushing these insights beyond toy problems and into the realm of useful real-world imaging needs, with applications in super-resolution microscopy, astronomy, and remote sensing.

Speaker's Bio

Michael R Grace is a graduating PhD student working with Professor Saikat Guha at the University of Arizona College of Optical Sciences. He has a background in classical and quantum physics and diffractive optics as well as experience in experimental super-resolution microscopy. His current research interests include optical sensing, quantum information theory, and optical machine learning.

2022-06-08 11:00:00

Ryotatsu Yanagimoto Stanford University

Harnessing Ultrashort Pulses Enables All-Optical Strong Coupling

Realizing a strong photon-photon coupling is a central goal in quantum nonlinear optics, holding a promise, e.g., for single-photon nonlinear optics and deterministic optical quantum computation. While bulk nonlinear optics offers a scalable and room-temperature solution, requirements for nonlinearity and loss are extremely demanding, which have not been realized to this date. In this talk, we propose a novel route to all-optical strong coupling: ultrashort pulses on dispersion engineered nanophotonics. In addition to the transverse field confinement provided by the waveguide, ultrashort pulses form “flying cavities” that enjoy tight longitudinal confinement, significantly enhancing the nonlinear coupling. In this regime, however, strong nonlinearity inevitably induces multimode non-Gaussian quantum dynamics that naïvely require an exponentially large Hilbert space. To this, we introduce our recent developments in model reduction techniques, i.e., approaches with matrix-product states and non-Gaussians supermode model, which enables us to numerically understand the nonlinear quantum dynamics of photons beyond conventional semiclassical (i.e., linearized) treatments. We then present a novel “temporal trapping” scheme to harness the multimode nature of quantum pulses, which we can leverage to construct, e.g., a deterministic photon-photon gate. State of the art in thin-film lithium niobate waveguides suggests that we are, in principle, already in the strong coupling regime using ultrashort pulses, and we expect our work to provide a generic framework to understand and engineer the rich but complicated dynamics of broadband photons on this unique frontier. References [1] R. Yanagimoto, R. Hamerly et al., “Temporal trapping of ultrashort pulses enables deterministic optical quantum computation”, arXiv:2203.11909. [2] R. Yanagimoto, E. Ng et al., “Onset of non-Gaussian quantum physics in pulsed squeezing with mesoscopic fields”, Optica 9, 379 (2022). [3] R. Yanagimoto et al., “Efficient simulation of ultrafast quantum nonlinear optics with matrix product states”, Optica 8, 1306 (2021). [4] R. Yanagimoto, T. Onodera et al., “Engineering a Kerr-Based Deterministic Cubic Phase Gate via Gaussian Operations”, Phys. Rev. Lett. 124, 240503 (2020).

Speaker's Bio

Ryotatsu Yanagimoto is a senior Ph.D. student in the group of Prof. Hideo Mabuchi at Stanford University. His research interest spans AMO physics in general, while he focuses on the science of quantum devices at present. He currently works on the theoretical research of broadband non-Gaussian quantum optics, aiming at understanding and engineering coherent multimode dynamics of photons on nonlinear nanophotonics beyond the conventional framework of Gaussian quantum optics. Previously, he worked at the University of Tokyo and RIKEN on experimental research of optical lattice clocks, where he received a B.E. He is a recipient of a Masason fellowship and a Stanford Q-FARM Ph.D. fellowship.

2022-03-30 11:00:00

Danna Freedman MIT

Chemical Approach to Quantum Information Science

Chemistry offers a unique approach to quantum information science, whereby we can harness the atomistic precision inherent in synthetic chemistry to create structurally precise, reproducible, and tunable units. By harnessing this minute control over the chemical environment we can design systems wherein we control the distance between spin centers, their intrinsic environment and their extrinsic environment. Specifically, this talk will focus on creating molecules that are analogues of NV centers which we dub molecular color centers. These molecules feature optical read-out of spin information and offer significant promise in the realm of sensing and potentially communication.

Speaker's Bio

Danna Freedman is the F. G. Keyes Professor of Chemistry at MIT. She received her Undergraduate degree from Harvard University, and her Ph.D. from University of California, Berkeley where she studied magnetic anisotropy in molecules. As a postdoc at MIT she engendered spin frustration in kagomé lattices to create quantum spin liquids. After completing her postdoctoral research at MIT, Danna moved to Northwestern University as an Assistant Professor, where she received tenure and was promoted to full professor. She recently moved to MIT as the F. G. Keyes Professor of Chemistry. Her laboratory’s research focuses on applying inorganic chemistry to address challenges in physics. Danna’s laboratory's research has been recognized by a number of awards including the ACS award in Pure Chemistry, the Presidential Early Career Award for Scientists and Engineers (PECASE), Camille Dreyfus Teacher-Scholar Award, and an NSF CAREER award.

2022-03-09 11:00:00

Carsten Schuck University of Münster

Integrated Quantum Technology on Nanophotonic Chips

Quantum Technology promises tremendous advances in information processing, communication, and sensing, but current implementations do not yet integrate all essential building blocks and neither scale to large system size. Here we focus on photonic approaches, which are a frontrunner for quantum communication applications but also hold promise for optical quantum computing, simulation, and remote sensing. We identify quantum light sources, nanophotonic circuit components and single-photon detectors as essential building blocks and show how these can be replicated in large numbers on semiconductor chips by leveraging modern nanotechnology. Lithographic techniques allow for integrating solid state single-photon sources into dielectric waveguides with high yield and tailor their emission characteristics using photonic crystal cavities. We show how photons supplied into on-chip networks can be processed using nanophotonic circuit elements, for which we introduce a novel reinforcement-learning-based inverse design technique that yields high-performance devices of minimal footprint. Waveguide-integrated superconducting nanowire single-photon detectors (SNSPDs) further satisfy the need for efficient on-chip detection capabilities. We realize SNSPDs in large numbers and combine leading performance parameters with efficient fiber optic interconnects, which we exploit for high-rate quantum key distribution. Progress towards integrating sources, circuits, and detectors on silicon chips will thus allow us to study systems aspects in complex quantum networks and expand current quantum technology capabilities.

Speaker's Bio

Professor Carsten Schuck works at the Center for NanoTechnology (CeNTech), the Center for Soft Nanoscience (SoN) and the Physics Institute of the University of Münster (Germany). His academic activities focus on quantum technology and nanophotonics, in particular the integration of quantum emitters and superconducting single-photon detectors with nanophotonic circuits. Before his appointment as full professor (2021), he was an as Assistant Professor in Münster (2016), after a postdoctoral fellowship at Yale University (USA) and work for ASML Research (The Netherlands). He studied physics in Hamburg, Munich, and Uppsala (Sweden) and obtained his PhD degree in Applied Physics for work with single-trapped ions at the Institute of Photonic Sciences, ICFO, in Barcelona (Spain). Prof. Schuck is the co-founder of Pixel Photonics, a start-up company that commercializes superconducting nanowire single-photon detectors.

2022-02-23 11:00:00

Vladimir M. Shalaev Purdue University

Hybrid Quantum Photonics

We will discuss some recent ideas and developments on how plasmonics and machine learning can be employed to dramatically speed up quantum process to make them immune to decoherence and how they can significantly improve the performance of quantum photonics devices and systems. Our recent discovery of single-photon emitters in technologically important SiN platform will be also discussed.

Speaker's Bio

Vladimir M. Shalaev, Scientific Director for Nanophotonics at Birck Nanotechnology Center and Distinguished Professor of Electrical and Computer Engineering at Purdue University, specializes in nanophotonics, plasmonics, optical metamaterials and quantum photonics. Prof. Shalaev has received several awards for his research in the field of nanophotonics and metamaterials, including the APS Frank Isakson Prize for Optical Effects in Solids, the Max Born Award of the Optical Society of America for his pioneering contributions to the field of optical metamaterials, the Willis E. Lamb Award for Laser Science and Quantum Optics, IEEE Photonics Society William Streifer Scientific Achievement Award, Rolf Landauer medal of the ETOPIM (Electrical, Transport and Optical Properties of Inhomogeneous Media) International Association, the UNESCO Medal for the development of nanosciences and nanotechnologies, and the OSA and SPIE Goodman Book Writing Award. He is a Fellow of the IEEE, APS, SPIE, MRS and OSA.

2022-02-16 11:00:00

Markus Aspelmeyer University of Vienna & Austrian Academy of Sciences

How to avoid the appearance of a classical world in gravity experiments (or: how to make use of home-office time...)

This talk is based on our recent experimental works on quantum controlling the center of mass degree of freedom of levitated solid-state systems - and the question whether these experiments could be extended to a regime in which one can probe the gravitational field generated by a delocalised quantum object. If possible, such "quantum Cavendish" experiments would not be described by our current theory of gravity. I will also use the time to show you what else we have been working on in Vienna during the last 24 months.

Speaker's Bio

Markus Aspelmeyer is Professor of Physics at the University of Vienna and Scientific Director of the Institute for Quantum Optics and Quantum Information (IQOQI) Vienna of the Austrian Academy of Sciences.

2022-02-02 11:00:00

Lorenzo Pavesi University of Trento

Physics and Applications enabled by integrated silicon photonic circuits

Here I will review few topics we are currently working on in the Nanoscience Laboratory of the University of Trento ( Specifically by using the silicon photonics platform we are working on non-hermitian photonics in taiji microresonators [1], on microresonator based time-delayed neural networks [2,3], on heralded single photon sources for MIR ghost spectroscopy [4] and on the use of single particle entanglement to produce self-testing quantum random number generators [5]. [1] Nonlinearity-induced reciprocity breaking in a single non-magnetic Taiji resonator arXiv:2101.06642 [2] Reservoir computing based on a silicon microring and time multiplexing for binary and analog operations arXiv:2101.01664 [3] Microring resonators with external optical feedback for time delay reservoir computing arXiv:2109.11486;A photonic complex perceptron for ultrafast data processing arXiv:2106.11050 [4] A silicon source of heralded single photons at 2 μm arXiv:2108.01031 [5] Certified quantum random number generator based on single-photon entanglement arXiv:2104.04452 Entropy certification of a realistic QRNG based on single-particle entanglement arXiv:2104.06092

Speaker's Bio

Lorenzo Pavesi is Professor of Experimental Physics at the Department of Physics of the University of Trento (Italy). He leads the Nanoscience Laboratory and director of the Quantum at Trento joint laboratory. He has directed 37 PhD students and more than 30 Master thesis students. His research activity concerned the optical properties of semiconductors. During the last years, he concentrated on Silicon based photonics where he looks for the convergence between photonics and electronics. He is interested in active photonics devices which can be integrated in silicon. Recent development is toward integrated quantum photonics and neuromorphic photonics. He is an ERC grantee. He is a frequently invited reviewer, monitor or referee for photonics projects by several grant agencies. He is an author or co-author of more than 500 papers, author of several reviews, editor of more than 15 books, author of 2 books and holds 9 patents. He is chief speciality editor of the section Optics and Photonics of Frontiers in Physics and founding editor of the series Photonic Materials and Applications, a joint initiative of SPIE and Elsevier. He is in the advisory board of Glass-to-Power and of Sybilla, two italian start-up. In 2001 he was awarded the title of Cavaliere by the Italian President for scientific merit. In 2010 and 2011 he was elected distinguished speaker of the IEEE- Photonics society. He is fellow of the IEEE, of SPIE, of AAIA and of the SIF.

2022-01-05 11:00:00

Thomas Krauss University of York

Beyond Q: The importance of the amplitude for nanophotonic resonances

Nanophotonic resonances have seen a sustained interest because of their ability to enhance light-matter interactions, with recent developments such as metasurfaces and bound states in the continuum (BIC) adding interest to the topic. Researchers typically aim to maximise the Q-factor as a measure for the interaction; this is true for both light emission, where Q/V (V: Volume) is the key parameter, but also for sensing, where QxS (S: Sensitivity) is the usual figure of merit. Here, we show that this picture can be overly simplistic and that it is essential to take losses and the resonance amplitude into account. Using sensors as an example, we present an ab-initio model and show that the performance is not optimised by simply maximising the Q, but by counterbalancing Q and amplitude. We compare different structures in light of this model and demonstrate high-sensitivity biological measurements with structures that achieve moderate Q but high resonance amplitude.  

Speaker's Bio

Prof Krauss achieved his first degree (“Diplom-Ingenieur”) in Cologne, Germany (1989), followed by a PhD in Electrical Engineering at Glasgow, UK 1992 on the topic of semiconductor ring lasers. He initiated the work on photonic crystals in the UK in 1993, a research field where he made pioneering contributions worldwide, spent a year at Caltech, Pasadena, CA in 1997 and became Professor of Physics at St Andrews, UK in 2000. He moved to the University of York, UK in 2012 to focus on light-matter interaction with biological systems, where he was also Strategy Champion “Technologies for the Future" 2015-2019. He has led major EU and UK research projects and currently holds a substantial research portfolio related to optical biosensors funded by EPSRC, the Wellcome Trust, and well supported by industry partners. His papers are well cited (h=90) and he is a Fellow of the Royal Society of Edinburgh, the Institute of Physics and the Optical Society. He was one of the founding editors of OSA's flagship journal Optica in 2014 and became its Deputy Editor in early 2020.

2021-12-08 11:00:00

Joyce Poon Max Planck Institute of Microstructure Physics and University of Toronto

Silicon integrated photonics for future “computing”

As the demands and forms of computers evolve, new hardware is needed to realize different types of computing interfaces. Foundry silicon photonics leverages the maturity of microelectronics manufacturing to fabricate photonic integrated circuits. Today, silicon photonics is mostly used in the short-wave infrared spectrum for fiber optic communication. I will discuss how foundry silicon photonics in the visible spectrum can be an enabling technology for future computing, addressing applications such as displays, neural implants, and quantum computing.

Speaker's Bio

Joyce Poon is the Managing Director at the Max Planck Institute of Microstructure Physics, Professor of Electrical and Computer Engineering at the University of Toronto, and an Honorary Professor in the Faculty of Electrical Engineering and Computer Science at the Technical University of Berlin. She currently serves as a Director-at-Large for Optica (formerly the Optical Society, OSA). She and her team specialize in integrated photonics on silicon. Prof. Poon obtained the Ph.D. and M.S. in Electrical Engineering from Caltech in 2007 and 2003 respectively, and the B.A.Sc. in Engineering Science (physics option) from the University of Toronto in 2002. Recognitions she has received include a Canada Research Chair (2012-2019), ECE Department Teaching Award (2017), OFC Top-Scored Paper (2017), the McCharles Prize for Early Research Career Distinction (2013), MIT TR35 (2012), and the IBM Faculty Award (2010, 2011). She is an Optica Fellow (formerly OSA).

2021-11-24 11:00:00

Dmitry Zimin Max Planck Institute of Quantum Optics

Petahertz optoelectronics via attosecond control of solids

High-order non-linear excitation of charge carriers in solids and gasses can be employed as a time gate for pulse waveform sampling. The temporal confinement of the event provides an attosecond temporal resolution and a petahertz detection bandwidth. The concept is applied to observe and control the optical properties of solids directly in the time domain. The light-matter-light pump-probe configuration allows using a sample medium and the injection pulse, to control and manipulate the test pulse waveform at ultrafast timescales. The encoded information is stored and can be further read out by a pulse waveform measurement, therefore making the light-matter-light interaction somewhat similar to the gate-drain-source transistor, but at ultrafast time-scales.

Speaker's Bio

2016 – 2021 Max Planck Institute of Quantum Optics / Ludwig Maximilian University of Munich (Ph.D in physics with honors) Web: Major: Ultrafast and attosecond physics in solids and gases Supervised by Dr. Nicholas Karpowicz and Prof. Ferenc Krausz Thesis referees: Prof. Ferenc Krausz, Prof. Mikhail (Misha) Ivanov, Prof. Immanuel Bloch, Prof. Joseph Mohr 2016 – 2021 International Max Planck Research School for Advanced Photon Science (Ph.D in physics with honors) Web: PhD Student. Munich, Germany Major: Ultrafast and attosecond physics in solids and gases 2014 – 2016 Ruhr-University-Bochum / University of Hamburg, Germany (M.Sc in lasers and photonics with honors) Web: Major: Non-linear Optics, Solid State Physics Thesis: “Strong field interactions of solids with Infrared and terahertz radiation” Supervised by Prof. Franz Kaertner and Prof. Evgeny Gurevich Ultrafast Optics and X-Rays Division, Center For Free Electron Laser Science (DESY) Hamburg, Germany 2012 – 2016 Additional modules taken from various institutions (Average grade 93%) Ludwig Maximilian University of Munich, University of Hamburg, Deutsches Elektronen-Synchrotron, Center For Free Electron Laser Science, University of Strasbourg, Dortmund University of Technology, Hamburg University of Applied Sciences Major: Physics, Electrical Engineering, Computer Science 2005 – 2010 Togliatti State University, Togliatti, Russia (Diploma with average grade 87%) Web: Major: Physics, Material Science, Mechanics ASSOCIATION: 11/2016 – present Max Planck Institute of Quantum Optics. Garching b. Munich, Germany Department: Attosecond Physics (Prof. Ferenc Krausz) Doktorand 04/2016 – 11/2016 Deutsches Elektronen-Synchrotron (DESY). Hamburg, Germany Department: CFEL, Ultrafast Optics and X-Rays (Prof. Dr. Franz X. Kärtner) Research Assistant (Strong field interaction of light with solids) 09/2015 – 03/2016 Ruhr-University-Bochum, Bochum, Germany Department: Experimentalphysik IV, Solid State Physics (Prof. Dr. Beatriz Roldan Cuenya) Research Assistant (Research in X-ray diffraction) 07/2015 – 09/2015: Deutsches Elektronen-Synchrotron (DESY). Hamburg, Germany Department: Photon Science Research Assistant (Research in non-linear optics. HHG from gas/solids) 02/2015 – 03/2016 Ruhr-University-Bochum, Bochum, Germany Department: Photonics and Terahertz Technology (Prof. Dr. Martin Hofmann) Research Assistant (Research in non-linear optics) 03/2014 – 09/2014 University of Hamburg / Deutsches Elektronen-Synchrotron (DESY). Hamburg, Germany Department: Institut für Experimentalphysik, Femtosecond X-ray physics (Prof. Dr. Markus Drescher) Research Assistant (Optical research for HHG experiments) 01/2014 – 09/2014 NXP Semiconductors (Former Phillips). Hamburg, Germany Department: Systems and Applications (Dirk Besenbruch) Assistant (Electronics development) 10/2013 – 02/2014 Hamburg University of Applied Sciences. Hamburg, Germany Department: Information and Electrical Engineering (Prof. Dr.-Ing. Lutz Leutelt) Tutor AWARDS, SCHOLARSHIPS, OTHER: • “Top university graduates 2016”. Ruhr University. Bochum, Germany • Award in International High School Mathematical Competition. Saint Petersburg, Russia • Russian State Scholarship for Especially Committed University Students. Togliatti, Russia • Award of university olympiad in descriptive geometry. Togliatti, Russia • 6 months student exchange program participant. New York, USA • Member of SPIE Students Chapter • PhD representative at Max Planck Institute of Quantum Optics, Germany (2019 - 2020)

2021-11-17 11:00:00

Armando Rastelli Johannes Kepler University of Linz

Semiconductor quantum dots as sources of highly-entangled photon pairs

Entanglement is one of the most fascinating aspects of quantum mechanics and an indispensable resource for emerging quantum technologies. Properly engineered semiconductor quantum dots (QDs) are capable of emitting highly entangled photon pairs with ultra-low multi-pair emission probability even at maximum brightness. In this seminar, we will discuss the structural and optical properties of QDs based on the (Al)GaAs material platform followed by their use in entanglement-based quantum key distribution. For a proof of principle, the quantum key generation was performed between two buildings of the JKU campus at a rate of about 130 bits/s. By embedding the QDs in state-of-the-art photonic structures, key generation rates in the hundreds of Mbit/s range are at reach.

Speaker's Bio

Prof. Armando Rastelli heads the Semiconductor Physics Division of the Johannes Kepler University of Linz, Austria since 2012. He obtained his PhD in Physics from the University of Pavia, Italy, in 2003. During his PhD he was research assistant at the ETH Zürich, Switzerland, and Marie-Curie-Fellow at the Technical University of Tampere, Finland. From 2003 to 2007 he was first Postdoc and then group leader at the Max-Planck-Institute of Stuttgart, Germany, and then at the Leibniz Institute of Dresden, Germany. In 2019 he was elected corresponding member of the Austrian Academy of Sciences. Throughout his career, he has been developing new methods to obtain, study, and control epitaxial quantum dots. The main current focus is on the optimization of quantum dots as quantum light sources for applications in photonic quantum technologies. He is coauthor of more than 230 peer-reviewed papers and has given more than 100 invited talks on the research activities of his group.

2021-11-10 11:00:00

Sunil Pai Stanford University

Scalability of programmable optics

Feedforward photonic optical circuits or meshes of programmable interferometers have recently been successfully demonstrated for potential in commercial applications ranging from sensing to machine learning to quantum computation. In this talk, I describe how to program and calibrate any feedforward circuit in presence of error via self-configuration. Incorporating this programming approach, I compare phase shift tolerance, loss tolerance, and fabrication error sensitivity as a function of circuit size and topology given an interferometer design. Our simulations and theory show that for a fixed circuit size, interfering modes in widely spaced (nonlocally interacting) waveguides increases error tolerance by orders of magnitude compared to interfering only modes in neighboring waveguides. Our results also explain why, in signal processing and sensing applications, this error-tolerant class of circuits can potentially scale fast Fourier transform, permutations, and low-rank matrix-vector products to thousands of input modes with minimal reduction in systematic error. Finally, I will present preliminary experimental results on a 4x4 mode photonic circuit to demonstrate a minimal example of programmable optics.

Speaker's Bio

Sunil Pai received the B.S. degree in physics and the M.S. degree in computer science from Stanford University in 2015 and 2016, respectively. He is currently a Ph.D. Student in Electrical Engineering at Stanford University studying photonic networks, coadvised by Olav Solgaard, David A.B. Miller, and Shanhui Fan. His research interests include machine learning, photonics, and quantum optics.

2021-10-20 11:00:00

Alex Tait Queen's University

Neuromorophic silicon photonics: principles, implementations, applications

Silicon photonic manufacturing has opened possibilities for new concepts in optical information science. Neural networks have proliferated throughout machine learning applications, but electronic implementations are reaching performance limits. Neuromorphic photonics is the pursuit of a bridge between photonic physics and neuromorphic applications. This talk addresses fundamentals and current status: what makes a device neuromorphic; what applications are promising?

Speaker's Bio

Alex Tait is an assistant professor of electrical and computer engineering at Queen's University, Kingston, ON, Canada. He was a NRC postdoctoral fellow in the Quantum Nanophotonics and Faint Photonics Group at the National Institute of Standards and Technology, Boulder, CO, USA. He received his PhD in the Lightwave Communications Research Laboratory, Department of Electrical Engineering, Princeton University, Princeton, NJ, USA under the direction of Paul Prucnal. His research interests include silicon photonics, neuromorphic engineering, and superconducting optoelectronics. Dr. Tait is a recipient of the National Science Foundation (NSF) Graduate Research Fellowship (GRFP) and is a member of the IEEE Photonics Society and the Optical Society of America (OSA). He is the recipient of the Award for Excellence from the Princeton School of Engineering and Applied Science, the Best Student Paper Award from the 2016 IEEE Summer Topicals Meeting Series, and the Class of 1883 Writing Prize from the Princeton Department of English. He has authored 15 refereed journal papers, (co)filed 8 provisional patents, created 7 open-source software packages, and contributed to the textbook Neuromorphic Photonics.

2021-09-15 00:00:00

Dorian Gangloff University of Cambridge

A quantum coherent interface of photons, an electron, and a nuclear spin ensemble

An ensemble of coherently interacting spins can host spectacular examples of spontaneous and driven quantum many-body phases, such as superradiance and time crystals. Further, if one can access coherently the quanta of such ensembles they can be exploited for quantum computational tasks and for the storage of quantum information in collective modes of the ensemble—a quantum memory. In semiconductor quantum dots, a single electron spin is a coherent interface to an isolated ensemble of nuclear spins. In an optically active quantum dot system, we have used all-optical techniques to show (i) coherent injection of nuclear spin-waves [1], (ii) sensing of a coherent single nuclear-spin excitation [2], and (iii) the presence of nuclear entanglement as a dark many-body state [3]. Combined with the exquisite quantum optical properties of quantum dots, these results open a new avenue for state engineering of a mesoscopic ensemble of spins connected to single photons, as promising towards quantum simulation, computation, and communication. [1] Gangloff et al. (2019), Science 364 [2] Jackson et al. (2021), Nat. Phys. 17 (5) [3] Gangloff et al. (2021), Nat. Phys. (In press)

Speaker's Bio

Dorian Gangloff got his PhD in Physics at MIT in 2016, working in the group of Prof. Vladan Vuletic on simulations of nano-friction with ultracold trapped ions. Since then, he has been a postdoctoral research fellow at the Cavendish Laboratory at the University of Cambridge, working in the group of Prof. Mete Atature on quantum information science with solid-state spins in semiconductors. In October 2021, he will begin a principal investigator position as a Royal Society University Research Fellow, and will start his own group in the department of Engineering Science at the University of Oxford in January 2022.

2021-07-14 00:00:00

Valeria Saggio University of Vienna (Austria)

Quantum speed-ups in reinforcement learning

The field of artificial intelligence (AI) has experienced major developments over the last decade. Within AI, of particular interest is the paradigm of reinforcement learning (RL), where autonomous agents learn to accomplish a given task via feedback exchange with the world they are placed in, called an environment. Thanks to impressive advances in quantum technologies, the idea of using quantum physics to boost the performance of RL agents has been recently drawing the attention of many scientists. In my talk I will focus on the bridge between RL and quantum mechanics, and show how RL has proven amenable to quantum enhancements. I will provide an overview of the most recent results — for example, the development of agents deciding faster on their next move [1] — and I will then focus on how the learning time of an agent can be reduced using quantum physics. I will show that such a reduction can be achieved and quantified only if the agent and the environment can also interact quantum-mechanically, that is, if they can communicate via a quantum channel [2]. This idea has been implemented on a quantum platform that makes use of single photons as information carriers. The achieved speed-up in the agent’s learning time, compared to the fully classical picture, confirms the potential of quantum technologies for future RL applications. [1] Sriarunothai, T. et al. Quantum Science and Technology 4, 015014 (2018). [2] Saggio, V. et al. Nature 591, 229–233 (2021).

Speaker's Bio

Valeria Saggio is currently a post-doctoral researcher at the University of Vienna (Austria), where she obtained her Ph.D. under the supervision of Prof. Philip Walther. She carried out her Master thesis at the University of Florence (Italy) and did an internship at the Queen's University Belfast (UK) during her studies at the University of Catania (Italy), where she obtained her B.A. and M.S. in Physics. Her research has a strong experimental focus on quantum computing with photonic platforms. During her Ph.D. she worked on demonstrating efficient detection of multipartite entanglement in photonic cluster states, as well as on applications of quantum mechanics to reinforcement learning. Her research interests include working with bulk as well as integrated optics.

2021-06-16 00:00:00

Mitsumasa Nakajima NTT Device Technology Labs

Scalable reservoir computing on coherent linear photonic processor

Recently, photonic implementation of artificial neural networks (ANNs) has catching interests because they have a great potential to reduce the operational power and latency beyond the electronic computing. The photonic circuit can solve large scale matrix operation, which is a dominant factor of ANN computation, with ultrafast propagation speed thanks to their inherent parallelism in space, frequency and time division. Here, I demonstrate a reservoir computing — a randomly connected recurrent neural network — specified on-chip photonic circuit capable of operating at sub-Peta-scale Multiply-Accumulate per second speeds [1]. I also explain the relationship between deep neural network and wave equation in the waveguide, which enables large-scale integration of photonic neuromorphic circuit in future [2]. [1] M. Nakajima et al., Commun. Phys. 4, 20 (2021). [2] M. Nakajima et al., arXiv:2006.13541

Speaker's Bio

Mitsumasa Nakajima received the M.E. and Ph.D. degrees in material science from the Tokyo Institute of Technology, Tokyo, Japan, in 2010 and 2015, respectively. In 2010, he joined Nippon Telegraph and Telephone (NTT) Laboratories, where he was involved in the development of large-scale optical switches. Recent his research interests are optical switches and their applications including neuromorphic photonics and optical signal processing for telecom. He was a recipient of the 8 research award including Young Engineer Award from the Institute of Electronics, Information and Communication Engineers (IEICE) of Japan

2021-05-19 00:00:00

Alex Gaeta Columbia University

Nonlinear photonics for quantum applications

Nonlinear integrated photonics is is on the cusp of realizing devices that will be widely used for applications in data communications, sensing, time-frequency metrology, and quantum information science. I will describe our recent work on developing nonlinear optical processes that can be used for generating squeezed states of light, quantum random number generation, and quantum frequency conversion.

Speaker's Bio

Gaeta received his Ph.D. in 1991 in Optics from the University of Rochester. He joined the faculty in the Department of Applied Physics and Applied Mathematics at Columbia University in 2015, where he is the David M. Rickey Professor. Prior to this, he was a professor in the School of Applied and Engineering Physics at Cornell University for 23 years. He has published more than 250 papers in quantum and nonlinear optics. He co-founded PicoLuz, Inc. and was the founding Editor-in-Chief of Optica. He is a Fellow of the OSA, APS, and IEEE, is a Thomson Reuters Highly Cited Researcher, and was awarded the 2019 Charles H. Townes Medal from the OSA.

2021-05-05 00:00:00

Hong Tang Yale University

Cavity electro-optics for microwave-to-optics conversion in the quantum ground state

Microwave-to-optical quantum converters represent an indispensable component for quantum communication in future quantum networks. To maintain quantum coherence, it is critical for such devices to operate at milli-Kelvin temperatures in the quantum ground state. Integrating photonics with superconductors at milli-Kelvin temperatures is particularly challenging since the optical excitation leads to unavoidable heating and excess microwave noise, thus placing the device systems in a thermal state as opposed to the desired ground state. In this work, we demonstrate efficient bidirectional microwave-to-optical conversion with an electro-optic device fabricated on an integrated AlN photonic platform in a milli-Kelvin environment. Our device operates near its quantum ground state and meanwhile offers 0.12% conversion efficiency – a rate that is suitable for building two-node quantum network through heralding protocols.[1] This fully integrated converter offers advantages including tunability, scalability, and high pump power handling capability. Harnessing a pulsed drive scheme, we suppress the microwave resonator’s thermal occupancy by 30 dB to as low as 0.09±0.06 quanta (92±5% ground state probability). By studying microwave noise thermodynamics, we unravel the underlying light-induced noise generation mechanisms, which provide important guidelines for future deployment of chipscale electro-optical devices as quantum links between superconducting quantum computers. [2,3] References [1] C. Zhong, Z. Wang, C. Zou, M. Zhang, X. Han, W. Fu, M. Xu, S. Shankar, M. H. Devoret, and H. X. Tang, Proposal for Heralded Generation and Detection of Entangled Microwave–Optical-Photon Pairs, Phys. Rev. Lett. 124, 10511 (2020). [2] W. Fu, M. Xu, X. Liu, C. L. Zou, C. Zhong, and X. Han, Ground-State Pulsed Cavity Electro-Optics for Microwave-to-Optical Conversion, ArXiv Preprint ArXiv (2020). [3] M. Xu, X. Han, C.-L. Zou, W. Fu, Y. Xu, C. Zhong, L. Jiang, and H. X. Tang, Radiative Cooling of a Superconducting Resonator, Phys. Rev. Lett. 124, 33602 (2020).

Speaker's Bio

Hong Tang is the Llewellyn West Jones, Jr. Professor of Electrical Engineering, Physics and Applied Physics at Yale University. His research utilizes integrated photonic circuits to study photon-photon, photon-phonon and photon-spin interactions as well as quantum photonics involving microwave and optical photons. He has been on Yale faculty since 2006. He is a recipient of the NSF CAREER Award and Packard Fellowship in Science and Engineering.

2021-04-07 00:00:00

Chris Anderson University of Chicago

Spin qubits in silicon carbide for quantum technologies

Defect spin qubits in silicon carbide (SiC) with associated nuclear spin quantum memories can leverage near-telecom emission and wafer-scale semiconductor device engineering for creating quantum technologies. Here, I highlight recent advances with the neutral divacancy defect (VV0) in SiC within the context of long-distance quantum communication and repeater schemes. Broadly, I will illustrate how quantum states can be controlled, tuned, and enhanced through their integration into SiC mechanical, photonic, and electrical devices. I will first describe the isolation of single VV0 defects in functional SiC optoelectronic devices, which allows for deterministic charge state control and terahertz tuning, but also surprisingly eliminates spectral diffusion in the optical structure of these defects. I will then discuss the entanglement and control of nuclear spin registers, and show how isotopic engineering can enhance both nuclear quantum memories and electron spin coherence times, while also demonstrating high fidelity control (99.98%), initialization, and readout. Briefly, I will further highlight recent results that universally protect spin coherence from electrical, magnetic, and thermal noise, resulting in T2*>20 ms in a naturally abundant crystal. This suite of results establishes SiC as a promising platform for scalable quantum science with optically-active spins.

Speaker's Bio

Chris is currently a postdoctoral scholar in the research group of David Awschalom at the University of Chicago at the Pritzker School of Molecular Engineering. Recently, he completed his PhD in Physics in the same group. Generally, Chris works on developing the physics and devices that will enable the next generation of quantum technologies using spins in semiconductors. He was awarded a NDSEG fellowship for his graduate work. Chris was a researcher in spintronics in Vanessa Sih’s group, and worked on ultrafast chemical physics in Roseanne Sension’s group at the University of Michigan, where he received a B.S in Chemistry and Physics. Chris has also worked on attosecond laser systems at the Max-Planck Institute for Nuclear Physics, and spent his early years as a molecular biology and genomics researcher.

2021-03-24 00:00:00

Jose Capmany Universitat Politecnica de Valencia

Field Programmable Photonic Gate Arrays: principles and applications

Programmable Integrated Photonics (PIP) is a new paradigm in integrated optics which seeks to provide versatile and flexible circuits, systems and subsystems adaptable to a myriad of applications. In a way PIP follows a similar itinerary as that of integrated electronics 4 decades ago but with substantial differences. In this talk, after a brief introduction to PIP, I will focus on the Field Programmable Photonic Gate Array (FPPGA) device, where a common hardware becomes multifunctional by suitable software programming. I will discuss the different hardware and software tiers involved in its development and will also provide experimental results obtained both within our research group as well as in our spinoff company. Finally, I will develop some application cases (including RF-Photonics) for the device and discuss possible future evolution paths.

Speaker's Bio

José capmany is professor of Photonics at the Universitat politècnica de València, Spain and leader of the Photonics Rsearch Labs ( He holds a MSc+BSc+PhD in Telecommunications Engineering and a MSc+BSc+PhD in Physics. His research stands out in two fields: Microwave Photonics and more recently the programmable integrated photonics. He has published over 640 papers in international JCR journals and conferences in different field of optical communications and photonic processing. He received the Premio Nacional de Investigación (National Research Award) Leonardo Torres Quevedo in Engineering in 2020 and the Premio Rey Jaime I in New Technologies (2012) for his contribution to the fields of Microwave and Programmable Photonics. In 2016 he obtained an Advanced Grant from the European Research Council (ERC) to develop the field of Programmable Integrated Photonics and in 2019 a Proof of Concept Grant from the same institution. He is a Fellow of the Institute of Electrical and Electronics Engineers (IEEE), the Optical Society of America (OSA) and the Institution of Engineering Technology (IET). He has co-founded 2 spinoff companies: VLC Photonics (, (specific purpose photonic circuit design house recently acquired by Hitachi High Technologies), and iPronics, Programmable Photonics (, (programmable optical chips), selected by Nature magazine as one of the 44 companies to watch within the SpinoffPrize 2020 call.

2021-03-17 00:00:00

Denis Sukachev University of Calgary

Interfaces between color centers and photons

Quantum networks enable a broad range of practical and fundamental applications spanning distributed quantum computing through sensing and metrology. A key element of such networks is an interface between photons and stationary quantum memories--qubits. I will first present the recent results on coupling the Silicon-Vacancy color centers in diamond to photons via nanophotonic cavities. Next, I will introduce a novel approach based on nano-optomechanics which we use to control electron spins of the Nitrogen-Vacancy centers in diamond with telecom photons at room temperature. The latter method does not involve qubit optical transitions and is insensitive to spectral diffusion. This approach can be applied to a broad range of solid-state qubits and paves the way to hybrid quantum networks.

Speaker's Bio

I received the undergraduate degree in Physics and Mathematics from the Moscow Institute of Physics and Technology and then in 2013 earned PhD in Physics from Lebedev Physical Institute for laser cooling and trapping of thulium atoms. In 2014, I moved to Massachusetts to work as a postdoc in Misha Lukin's group at Harvard University. Our sub-team was focused on study of the silicon-vacancy defects in diamond -- a new promising color center for quantum networking. In 2019, I joined Paul Barclay's lab at the University of Calgary as a staff scientist to develop a new spin-photon interface based on cavity optomechanics.

2021-03-10 00:00:00

Florian Marquardt Max Planck Institute for the Science of Light

Self-learning Machines based on Hamiltonian Echo Backpropagation

Physical learning machines use physical dynamics to achieve the same kind of general information processing and training that artificial neural networks are known for, but possibly faster and more energy-efficient. Self-learning machines can be defined as an ambitious subset of physical learning machines: They can be trained without requiring any form of external feedback to update the trainable parameters inside the device. In this talk, I will describe a new general idea that can be used to realize self-learning starting from any kind of Hamiltonian system with time-reversible dynamics. I will explain the reasoning and intuitive ideas behind it, as well as the ingredients that will be useful in building such devices in various physical platforms.

Speaker's Bio

Since 2016, Florian Marquardt leads the theory division of the Max Planck Institute for the Science of Light in Erlangen, Germany. His work covers the intersection of nanophysics and quantum optics. Research topics include cavity optomechanics, topological transport, quantum many-body dynamics, and the interface between machine learning and physics. After defending his thesis in 2002 in Basel, Switzerland, he was a postdoctoral fellow at Yale before becoming a junior research group leader at the Ludwig-Maximilians-Universität Munich and finally a full professor and subsequently Max Planck director at Erlangen.

2021-03-03 00:00:00

Jens Eisert Berlin Free University - Institut für Theoretische Physik

Semi-device-independent benchmarking, certification, and tomography

At the same time as the development of quantum technologies progresses rapidly, new demands concerning the certification of their operation emerge. A question relevant for the application of various quantum technologies consequently is how the user can ensure the correct functioning of the quantum devices [1]. In a number of instances, specifically in quantum simulation and quantum computing, challenges in appropriately benchmarking components or entire protocols constitute a widely acknowledged bottleneck. This talk will suggest several new takes to the problem at hand: We will see how data from SPAM-robust randomized benchmarking [2] can be used to perform process tomography of quantum gates in an experimentally-friendly and provably sample optimal fashion [3], making use of a machinery of compressed sensing and exploiting structure - that is to say, the components of a quantum circuit. We will see how quantum states can be characterizes provably even with imperfect detectors in what could be called semi-device-dependent tomography [4]. The issue becomes more challenging when one aims at certifying the functioning of an entire device. We will look at limitations to black-box verification for sampling problems that show a quantum advantage or "supremacy" [5], will have a fresh look at Hamiltonian learning [6] and will see that in some instances [7], one can ironically certify the correctness of a device even if one cannot efficiently predict its performance. [1] Quantum certification and benchmarking, J. Eisert, D. Hangleiter, N. Walk, I. Roth, D. Markham, R. Parekh, U. Chabaud, E. Kashefi, Nature Reviews Physics 2, 382-390 (2020). [2] Randomized benchmarking for individual quantum gates, E. Onorati, A. H. Werner, J. Eisert, Phys. Rev. Lett. 123, 060501 (2019). [3] Recovering quantum gates from few average gate fidelities, I. Roth, R. Kueng, S. Kimmel, Y.-K. Liu, D. Gross, J. Eisert, M. Kliesch, Phys. Rev. Lett. 121, 170502 (2018). [4] Semi-device-dependent blind quantum tomography, I. Roth, J. Wilkens, D. Hangleiter, J. Eisert, arXiv:2006.03069 (2020). [5] Sample complexity of device-independently certified quantum supremacy, D. Hangleiter, M. Kliesch, J. Eisert, C. Gogolin, Phys. Rev. Lett. 122, 210502 (2019). [6] In preparation (2020). [7] J. Haferkamp, D. Hangleiter, A. Bouland, B. Fefferman, J. Eisert, and J. Bermejo-Vega, arXiv:1908.08069, Phys. Rev. Lett. (2020).

Speaker's Bio

He is known for his research in and has made numerous contributions to quantum information science and quantum many-body theory in condensed matter physics. He has made significant contributions on entanglement theory and the study of quantum computational models, as well as quantum optical implementations of protocols in the quantum technologies and the study of complex quantum systems. He is also notable as one of the co-pioneers of quantum game theory with Maciej Lewenstein and PhD advisor Martin Wilkens.

2021-02-24 00:00:00

Brian Gerardot Heriot-Watt University

Quantum Light and Strongly Correlated Electronic States in a Moiré Heterostructure

The unique physical properties of two-dimensional materials, combined with the ability to stack unlimited combinations of atomic layers with arbitrary crystal angle, has unlocked a new paradigm in designer quantum materials. For example, when two different monolayers are brought into contact to form a heterobilayer, the electronic interaction between the two layers results in a spatially periodic potential-energy landscape: the moiré superlattice. The moiré superlattice can create flat bands and quench the kinetic energy of electrons, giving rise to strongly correlated electron systems. Further, single particle wave packets can be trapped in the moiré potential pockets with three-fold symmetry to form ‘quantum dots’ which can emit single photons. Here I will present magneto-optical spectroscopy of a 2H-MoSe2/WSe2 heterobilayer device with ~3° twist. I will discuss moiré-trapped inter-layer excitons, which can emit quantum light, and intra-layer excitons, which exhibit a large number of strongly correlated electron and hole states as a function of fractional filling.

Speaker's Bio

Professor Brian Gerardot holds a Chair in Emerging Technology from the Royal Academy of Engineering and leads the Quantum Photonics Lab at Heriot-Watt University in Edinburgh, Scotland (more information: His research, at the interface of quantum optics, condensed-matter physics, and materials science, aims to engineer and controllably manipulate quantum states in semiconductor devices, in particular with III-V quantum dots and van der Waals heterostructure devices. Brian obtained a BS from Purdue University and a PhD in Materials Science from UC Santa Barbara.

2021-02-17 00:00:00

Eric I. Rosenthal JILA

Efficient and low-backaction quantum measurement using a chip-scale detector

Superconducting qubits are a leading platform for scalable quantum computing and quantum error correction. One feature of this platform is the ability to perform projective measurements orders of magnitude more quickly than qubit decoherence times. Such measurements are enabled by the use of quantum-limited parametric amplifiers in conjunction with ferrite circulators - magnetic devices which provide isolation from noise and decoherence due to amplifier backaction. Because these non-reciprocal elements have limited performance and are not easily integrated on-chip, it has been a longstanding goal to replace them with a scalable alternative. Here, we demonstrate a solution to this problem by using a superconducting switch to control the coupling between a qubit and amplifier. Doing so, we measure a transmon qubit using a single, chip-scale device to provide both parametric amplification and isolation from the bulk of amplifier backaction. This measurement is also fast, high fidelity, and has 70% efficiency, comparable to the best that has been reported in any superconducting qubit measurement. As such, this work constitutes a high-quality platform for the scalable measurement of superconducting qubits.

Speaker's Bio

Eric I. Rosenthal is a Ph.D. student at the University of Colorado, Boulder, under the advisement of Professor Konrad Lehnert at JILA. He received his B.A. and M.S. in physics from the University of Pennsylvania in 2015 and is expected to receive his Ph.D. in physics in the spring of 2021. His research interest is in the advancement of quantum information technology using superconducting systems. In particular, his research has involved the development of superconducting switches, amplifiers, and non-reciprocal devices to improve the measurement of superconducting qubits.

2021-02-10 00:00:00

Boubacar Kante UC Berkeley

Topological light sources and sensors

Topology plays a fundamental role in contemporary physics and enables new information processing schemes and wave device physics with built-in robustness. Recently, significant efforts have been devoted to transposing topological principles to bosonic systems. In the first part of this talk, I will discuss our invention of the first topological laser, a non-reciprocal light source capable of coupling stimulated emission to selected waveguide output in a controllable manner. I will also discuss unique optical devices based on this platform. In the second part of the talk, I will discuss our recently proposed scheme to systematically implement singularities known as exceptional points in passive plasmonics. I will discuss the new scheme and how we overcame current immuno-assay nano sensing record with plasmons by more than two orders of magnitude.

Speaker's Bio

Boubacar Kanté is an associate professor of Electrical Engineering and Computer Sciences (EECS) at the University of California Berkeley. In 2010, he received a Ph.D degree in Engineering/Physics from “Université de Paris Sud” (Orsay-France). He was assistant professor and then associate professor of Electrical and Computer Engineering (ECE) at UC san Diego from 2013 to 2018. His research interests include wave-matter interaction and nano-optics. Boubacar Kanté is a 2020 Moore Inventor Fellow. He received the 2017 Office of Naval Research (ONR) Young Investigator Award, the 2016 National Science Foundation (NSF) Career Award, The best undergraduate teacher award from UC San Diego Jacob School of Engineering in 2017, the 2015 Hellman Fellowship, the Richelieu Prize in Sciences from the Chancellery of Paris Universities for the best Ph.D in France in Engineering, Material Science, Physics, Chemistry, Technology in 2010, the Young Scientist Award from the International Union of Radio Science (URSI) in Chicago in 2007, the Fellowship for excellence from the French Ministry of Foreign Affairs in 2003 for his undergraduate studies, a Research Fellowship from the French Research Ministry for his Ph.D studies.

2021-02-03 00:00:00

Martin Suchara Argonne National Laboratory

Quantum Network Simulations - Towards Reliable, Scalable, and Secure Quantum Network Architectures

Recent advances in quantum information science enabled the development of quantum communication network prototypes and created an opportunity to study full-stack quantum network architectures. This talk introduces SeQUeNCe, a comprehensive, customizable quantum network simulator. Our simulator consists of five modules: Hardware models, Entanglement Management protocols, Resource Management, Network Management, and Application. This modularized framework is suitable for simulation of quantum network prototypes that capture the breadth of current and future hardware technologies and protocols. We implement a comprehensive suite of network protocols and demonstrate the use of SeQUeNCe by simulating a quantum key distribution network, a teleportation network, and a metropolitan quantum network in the Chicago area consisting of nine routers equipped with quantum memories. Quantum network simulations are expected to play an increasingly important role in designing future quantum networks that scale to long distances and large number of hosts, and meet the latency, reliability and security needs of emerging applications. SeQUeNCe is freely available on GitHub.

Speaker's Bio

Martin Suchara is a Computational Scientist at Argonne National Laboratory and at the University of Chicago with expertise in quantum computing and quantum communication. His group focuses on theoretical studies of photonic quantum networks, quantum error correction, quantum simulations, and optimizations of the quantum computing software stack. Dr. Suchara is the leader of the Simulation & Systems Thrust of the Q-NEXT National Quantum Information Science Research Center based at Argonne National Laboratory. Prior to joining Argonne he worked as a Principal Scientist at AT&T Labs and received postdoctoral training in quantum computing from UC Berkeley and the IBM T. J. Watson Research Center. Dr. Suchara received his PhD from the Computer Science department at Princeton University.

2021-01-27 00:00:00

Amir Ghadimi Swiss Center for Electronics and Micro/nano technology (CSEM)

Electro-optic and nonlinear photonic integrated circuit (PIC) platform based on lithium niobate on insulator (LNOI)

Lithium niobate on insulator (LNOI) is one of the most promising emerging platforms for photonics integrated circuits (PICs) that comprises a unique set of interesting optical properties such as: a high electro-optic (EO) coefficient, high intrinsic 2nd and 3rd order nonlinearities, and a large transparency window (350 nm - 5500nm). Lithium niobate (LiN) has attracted a lot of attention since the 1970s, however, most of its industrial success has been limited to devices made from bulk LiN crystals in the form of free-space or fiber-coupled components using ion-implanted waveguides. Recent advancements in bonding of single crystal thin films of LiN onto silicon substrates (LNOI), opens a new avenue to explore the advantages of LiN in the context of PICs and to benefit from their miniaturization, cost reduction, scalable manufacturing and integration. In the LNIO platform, waveguides are fabricated using reactive ion etching (RIE) in a LiN thin film which allows for significantly higher refractive index contrast () compared to traditional waveguides made by ion implantation technology in bulk crystals (). This allows to reduce the optical mode volume by more than ~100x. Such high confinement not only results in more efficient and faster modulators but also in significantly smaller bending radii and PIC footprints, which, ultimately enables designing complex PICs with tens of components in a millimeters-size chips. In an LNOI platform we can combine high performance active EO components such as modulators, phase shifters and tunable cavities with unique optical nonlinearities at a wide range of wavelengths to achieve truly novel functionalities and PIC designs that are beyond the capabilities of any PIC platform commercially available today. In this talk I will present the recent progress at CSEM toward developing an EO and nonlinear PIC platform based on LNOI. We start by reviewing the advantages of LNOI platform for various application areas such as telecom, optical signal processing, programmable PICs, LiDAR, spectroscopy, quantum information processing, and nonlinear photonic. Then we will review how LNOI platform fits within the industrial PIC ecosystem and how it compares with other PIC platforms such as Si, SiN and InP. We then discuss the challenges in fabricating high quality photonics circuits in LNOI and will review CSEM’s recent results in design, fabrication, and testing of high quality LNOI photonic circuits. Next, we briefly review few successful example and experiments performed by CSEM or in collaboration with other groups in the areas of nonlinear photonics and quantum information processing. Finally, I will present the future perspectives of our LNOI platform including the process design kit (PDK) library and the means that interested parties can access our platform as a pre-commercial foundry service.

Speaker's Bio

Dr. Amir H. Ghadimi is currently a senior scientist and a group leader at the Swiss Center for Electronics and Micro/nano technology (CSEM). He is currently leading the efforts at CSEM in the areas of PICs and PIC based sensing where together with his team they are developing two PIC platforms based on SiN and LNOI. He obtained his PhD. in electrical engineering in 2018 from the Swiss Federal Institute of Technology (EPFL). His PhD research focused on quantum optomechanics, precision sensing and applications of high Q optical and mechanical resonators. He is the recipient of Swiss national funding (SNF) Bridge discovery grant (2020), Swiss Physical Society (SPS) 2019 young scientist award, Swiss Nanotechnology best PhD award (2018) and European frequency and time forum (EFTF) best paper award (2018).

2021-01-13 00:00:00

Kin Chung Fong Raytheon BBN Technologies

Graphene-based single-photon detector for quantum information science and astrophysics

High sensitivity photon detectors are essential in qubit measurement and remote entanglement, as well as dark matter detection and observing the cosmic infrared background in astrophysics. However, sensing in microwave and far-infrared spectrum is challenging because of the low photon energy. In this talk, we will present how to leverage the giant thermal response of graphene electrons for photon detection. Interestingly, when our graphene bolometer achieves a record-high sensitivity of 10-19 W/Hz1/2, this sensitivity is limited, no longer by extrinsic factors but, by the statistical thermal fluctuation intrinsic to the graphene electrons as a canonical ensemble at 0.2 K [1]. Using the graphene-based Josephson junction, we demonstrate the single-photon detection in the infrared regime by observing the photon shot noise [2]. As an outlook, we will discuss how the unique properties of two-dimensional materials will open new opportunities in quantum information science. [1] Nature 586, 42 (2020) [2] arXiv:2011.02624.

Speaker's Bio

Born and raised in Hong Kong, Dr. Kin Chung Fong came to the United States to pursue his PhD under the supervision of Prof. Chris Hammel at Ohio State University. This is where KC develops his passion on high sensitivity experiments to observe new physical phenomena that cannot be otherwise measured. These include detecting a single electron spin magnetic resonance for nanoscale MRI, measuring superconducting qubits with quantum-limit amplifications, and detecting Dirac fluid in graphene. After his postdoc at Caltech, KC joined BBN Technologies in 2013. His research now focuses on studying the fundamental physics of strongly interacting Dirac and Weyl fermions in condensed matter systems with their connections to holographic principle, and developing the Josephson junction single photon detector for quantum information science, radioastronomy, and the search of dark matter axions. KC loves spending time outdoor with his family during weekends and learning new things from friends and collaborators, especially over a coffee!

2020-12-16 00:00:00

Wil Kao Stanford University

Topological pumping of a 1D dipolar gas into strongly correlated prethermal states

Highly excited eigenstates of interacting quantum systems are generically “thermal,” in the sense that physical observables behave as they would in thermal equilibrium--all initial conditions give rise to locally thermal behavior at times past the intrinsic dynamical timescale. Systems in which thermalization is absent are of great fundamental interest because they violate equilibrium statistical mechanics, and of technological interest because some quantum information encoded in these states evades decoherence. For the purpose of tackling this line of inquiry, ultracold neutral atoms in dilute gas offers a suitable tabletop platform that is well isolated from the environment and readily scalable to the thermodynamic limit. In this talk, I will describe our recent efforts of creating nonthermal states in a bosonic quantum gas of dysprosium, the most magnetic element, confined in quasi-1D waveguides. With repulsive long-range dipolar interactions that are two orders of magnitude stronger than alkali atoms, a highly excited super-Tonks-Girardeau gas is stabilized against collapse and thermalization. Stiffness and energy-per-particle measurements indicate that the system is dynamically stable regardless of short-range contact interaction strength. This metastability enables the cycling of contact interactions from weakly to strongly repulsive, then strongly attractive, and finally weakly attractive via two neighboring magnetically tuned collisional resonances. Iterating this quantum holonomy cycle allows an energy-space topological pumping method to create a hierarchy of increasingly excited prethermal states. In addition to being the first experimental realization of a dipolar Luttinger liquid, the result opens up an unexplored regime of quantum control and may have wide-ranging implications for understanding the onset of chaos in near-integrable systems.

Speaker's Bio

Wil Kao is an Applied Physics Ph.D. candidate at Stanford University, where he works on quantum simulation using dipolar quantum gases under the supervision of Prof. Benjamin Lev. He holds a B.A.Sc. in Engineering Science from the University of Toronto.

2020-12-09 00:00:00

Artur Hermans UGent

Micro-transfer-printing of thin-film devices on silicon nitride photonic integrated circuits: on-chip lasers, modulators, and detectors

Silicon nitride photonic integrated circuit (PIC) technology has come forth as one of the main photonic integration platforms. Silicon nitride PIC technology has many great features such as low waveguide loss, a wide transparency range (400 nm – 4000 nm), and the possibility of low-cost mass manufacturing using CMOS infrastructure. Yet, many applications require on-chip lasers, modulators, and detectors, which are not available in standard silicon nitride PIC technology. This talk will show how a technique called micro-transfer-printing can be used to integrate thin-film devices, made out of various materials, with silicon nitride PICs to realize on-chip lasers, modulators, and detectors. Micro-transfer-printing can be done in a massively parallel fashion on a wafer-scale, thereby offering a path to high-volume, low-cost production.

Speaker's Bio

Artur did his BSc degree in Engineering (Electronics and information technology) from the Vrije Universiteit Brussel in 2012. Afterwards, he entered the European MSc in Photonics program during which he spent a semester at Ghent University, the Vrije Universiteit Brussel, the University of St Andrews and the Swiss Federal Institute of Technology in Lausanne (EPFL). At EPFL, he did his master's thesis with Professor T. J. Kippenberg. In 2014, he joined the Photonics Research group to work on low-temperature processed thin films of second-order nonlinear optical materials for silicon nitride photonic integrated circuits, under supervision of Professor R. Baets and Professor S. Clemmen. For this work he was awarded a PhD degree in 2019. Currently, he is working as a postdoc in the Photonics Research Group on III-V-on-SiN mode-locked lasers. Artur's work at MIT will focus on visible-spectrum photonics for quantum control, with a particular focus on cold atom control with our CUA collaborators Profs Vuletic, Lukin, and Greiner.

2020-12-02 00:00:00

Laura Waller UC Berkeley

End-to-end learning for computational microscopy

Computational imaging involves the joint design of imaging system hardware and software, optimizing across the entire pipeline from acquisition to reconstruction. Computers can replace bulky and expensive optics by solving computational inverse problems. This talk will describe end-to-end learning for development of new microscopes that use computational imaging to enable 3D fluorescence and phase measurement. Traditional model-based image reconstruction algorithms are based on large-scale nonlinear non-convex optimization; we combine these with unrolled neural networks to learn both the image reconstruction algorithm and the optimized data capture strategy.

Speaker's Bio

Laura Waller is the Ted Van Duzer Associate Professor of Electrical Engineering and Computer Sciences (EECS) at UC Berkeley, a Senior Fellow at the Berkeley Institute of Data Science, and affiliated with the UCB/UCSF Bioengineering Graduate Group. She received B.S., M.Eng. and Ph.D. degrees from the Massachusetts Institute of Technology (MIT) in 2004, 2005 and 2010, and was a Postdoctoral Researcher and Lecturer of Physics at Princeton University from 2010-2012. She is a Packard Fellow for Science & Engineering, Moore Foundation Data-driven Investigator, Bakar Fellow, OSA Fellow and Chan-Zuckerberg Biohub Investigator. She has recieved the Carol D. Soc Distinguished Graduate Mentoring Award, Agilent Early Career Profeessor Award (Finalist), NSF CAREER Award and the SPIE Early Career Achievement Award.

2020-11-25 00:00:00

Peter O'Brien Tyndall National Institute

Photonic Packaging & Systems Integration - from Research to Pilot Line Manufacturing

This talk will give an overview of Tyndall’s capabilities in developing advanced photonic and electronic sub-systems and how these are integrated to produce fully functioning prototypes. The talk will also present Tyndall’s capabilities to enable scale-up from prototypes to pilot scale manufacturing and the drive to develop packaging standards. The talk will also discuss new research activities to develop a more scalable packaging technology for mass markets, taking lessons from the electronics industry to build a new global standard in photonic packaging.

Speaker's Bio

Prof. Peter O’Brien is head of the Photonics Packaging & Systems Integration Group at the Tyndall Institute, University College Cork in Ireland. He is also Director of the PIXAPP European Packaging Pilot Line (, Director of the new European Photonics Innovation Academy and Deputy Director of the Science Foundation Ireland Photonics Centre, IPIC. He previously founded and sold a photonics start-up company and was a researcher in millimeter wave devices at Caltech and NASA’s Jet Propulsion Laboratory.

2020-11-04 00:00:00

Xiadong Xu University of Washington

Phonons and Excitonic Complex in a Monolayer Semiconductor

The coupling between spin, charge, and lattice degrees of freedom plays an important role in a wide range of fundamental phenomena. Monolayer semiconductor is an emerging platform for studying these coupling effects due to unique spin-valley locking physics for hosting rich excitonic species and reduced screening for strong Coulomb interaction. In this talk, I will present the observation of both symmetry-allowed and -forbidden valley phonons, i.e. phonons with momentum vectors pointing to the corners of Brillouin zone, in a monolayer semiconductor WSe2. From the analysis of Landé g-factors and emission polarization of photoluminescence peaks, we identified the efficient intervalley scattering of quasi particles in both exciton formation and light emission process. These understandings enable us to unravel a series of photoluminescence peaks as valley phonon replicas of neutral and charged dark excitons, as well as deeply bound excitonic states with anomalously long population lifetime (> 5 µs). Our work not only shows monolayer WSe2 is a prime candidate for studying interactions between spin, pseudospin, and zone-edge phonons, but also opens opportunities to engineer collective quantum optical phenomena using homogenous intrinsic defect-bound excitons in ultraclean two-dimensional materials.

Speaker's Bio

Xiaodong Xu is a Boeing Distinguished Professor in the Department of Physics and the Department of Materials Science and Engineering at the University of Washington. He received his PhD (Physics, 2008) from the University of Michigan and then performed postdoctoral research (2009-2010) at the Center for Nanoscale Systems at Cornell University. His nanoscale quantum optoelectronics group at University of Washington focuses on creation, control, and understanding of novel device physics based on two-dimensional quantum materials.

2020-10-14 00:00:00

Wim Bogaerts Ghent University

Variability-aware circuit design techniques for silicon photonic circuits

Silicon Photonics is probably the only technology that really enables large-scale integration of photonic building blocks. This is made possible by the high-end manufacturing technology developed for the CMOS industry, combined with the very high refractive index contrast of silicon and silicon dioxide. This allows submicron waveguides that can be packed close together on a chip. However, the high index contrast makes the silicon waveguides also extremely sensitive to fabrication variations. When combining many elements in a circuit, this variability will affect the overall circuit yield, limiting the effective scale of the circuits. Therefore, circuit design for silicon photonics needs to incorporate the effects of fabrication variations early in the design process, optimizing the circuit layout to maximize the yield. We will discuss these effects and the workflows needed to implement variability aware design for silicon photonics.

Speaker's Bio

Wim Bogaerts is a professor in the Photonics Research Group at Ghent University and IMEC. He completed his PhD in 2004, pioneering the use of CMOS tools to make photonic circuits. Between 2000 and 2010, he was instrumental in the buildup of IMEC’s silicon photonics technology. In parallel, he also started developing the design tool IPKISS to implement complex silicon photonic circuits. In 2014, he co-founded Luceda Photonics, bringing his design tools to the market. In 2016 he returned full-time to Ghent University and IMEC on research grant of the European Research Council. His research now focuses on the challenges for large-scale photonic circuits and the new field of programmable photonics. He is a senior member of IEEE, OSA and SPIE.