Seminars
Spring 2024
The Spring 2024 Seminar Series is via zoom. For questions on upcoming seminars, contact us here.
January 31, 2o24
Tailoring resistive switching materials for neuromorphic computing applications
Nareg Ghazikhanian
University of California, San Diego
Various materials exhibit resistive switching (RS), a useful feature which lends well to the development of novel bioinspired electronic devices, notably artificial neurons and synapses for neuromorphic computing. This effect can often manifest through the percolation of conducting filaments or the formation of transverse barriers. The location and switching parameters of RS are often impacted by inherent material defects which pose a challenge for scalability. By selectively engineering defects in VOx using a focused ion beam, we report a novel method of locally tuning a material’s electronic properties (i.e. conductivity and metal-insulator transition temperature) and by extension, controlling the location and geometry of RS. In this talk, I will provide a basic introduction to neuromorphic computing concepts and describe how RS materials can be engineered to emulate neuronal and synaptic functionalities. I will discuss a series of experiments in which we were able to localize an electrically driven insulator-to-metal transition through defect engineering and the implications this has on energy-efficiency (where a greater than 3 orders of magnitude reduction in switching power is observed). I will conclude my talk by discussing various characterization methods (including X-ray nanoprobe, near-field optical microscopy, infrared emissivity, etc.) used to investigate potential changes in RS mechanism and how resistive switching materials offer promising avenues for new energy-efficient biomimetic circuitry.
Nareg Ghazikhanian is a PhD candidate in the Materials Science Program at UC San Diego working in the physics department with professor Ivan Sculler. He received a B.S. in Nanoengineering in 2017 and a M.S. in Materials Science in 2019 from UC San Diego. Nareg’s work focuses on locally modifying the electronic structure of complex oxides via defect engineering and characterizing their structural, electronic, and magnetic properties.
February 07, 2024
Two-dimensional Materials for Bio-realistic Neuromorphic Hardware
Dr. Vinod K. Sangwan
Research Associate Professor
Materials Science and Engineering, Northwestern University
TBD Brain-inspired computing hardware is emerging as an alternative to Si CMOS to solve the looming energy crisis of processing rapidly increasing generation rate of digital data. Conventional non-volatile memories can realize highly parallelized in-memory computing in neural networks, but they lack the adaptability and reconfigurability that are the key attributes of low-energy biological systems. To this end, neuromorphic devices based on 2D materials embody bio-realistic tunable learning, coupled state variables, non-linear responses, and multi-terminal architectures of synapses. In this talk, I will portray the promise of 2D materials for this technology by drawing connections between fundamental properties, form factors, and required functionalities in artificial synapses, neurons, and network architectures.[1-4] As a few examples, MoS2 memtransistors show bio-realistic synaptic learning in scalable crossbar arrays for higher-dimensional dynamic neural networks.[5] Anomalous ferroelectricity in bilayer graphene moiré synaptic transistors achieves unprecedented adaptive learning.[6] Dual-gated, self-aligned, mixed-dimensional Gaussian heterojunction transistors realize not only complex spiking behavior but also enable low-power hardware for machine learning algorithms for edge computing.[7,8]
References: [1]: Nature Nano. 10, 403 (2015) [2]. Nature 554, 500 (2018) [3] Nature Nano. 15, 517 (2020) [4] Advanced Materials 2108025 (2022) [5] Matter 5, 4133 (2022) [6] Nature 624, 551 (2023) [7] Nature Comm. 11, 1565 (2020) [8] Nature Electronics 6, 862 (2023)
Dr. Vinod K. Sangwan is a Research Associate Professor in the Department of Materials Science and Engineering at Northwestern University (NU). He obtained a B.Tech. in Engineering Physics from the Indian Institute of Technology Mumbai and a Ph.D. in physics from the University of Maryland (UMD) College Park. Dr. Sangwan received the Iskraut award during his graduation from UMD and recently received the 2021 IEEE Chicago Outstanding Senior Research and Development award. His research interests include nanoelectronics, neuromorphic computing, renewable energy, and quantum information science. He has published over 100 peer-reviewed journal papers in journals like Science, Nature, Nature Nanotechnology, Nature Materials, Nature Communications, etc., and 12 granted and pending patents. At NU, he has mentored four post-doctoral researchers and three dozen graduate and undergraduate students and is a co-principal investigator on multiple grants totaling $4 million. He participates in teaching at NU, local outreach activities, and leadership roles in APS, MRS, and IEEE.
Spring 2023
The Spring 2023 Seminar Series is in Perkins Hall, Room 216 at the University of Tennessee at 3 pm on Wednesdays.
The seminars are also available via zoom. For questions on upcoming seminars, contact us here.
February 01, 2023
NISQ Computing on a Complete Graph of Superconducting Qubits — Part I
Dr. Michael Geller
University of Georgia
Current quantum computing architectures lack the size and fidelity required for universal fault-tolerant operation, limiting the experimental implementation of key quantum algorithms to all but the smallest problem sizes. In this talk I’ll review the limitations of gate-based quantum computing with noisy intermediate-scale quantum (NISQ) processors, and introduce an alternative, non-gate-model approach that is ideally suited for today’s superconducting qubits. In this approach, computation is performed in the single-excitation subspace (SES) of a fully connected graph of n tunably coupled qubits. In contrast to the gate model, arbitrary nxn unitaries as well as controlled unitaries can be implemented in a constant number of steps. I’ll discuss the strengths and weaknesses of SES approach, and show an experimental demonstration of the technique applied to the simulation of high-temperature atomic collisions.
Dr. Michael Geller received his PhD in Physics from the University of California, Santa Barbara, in 1994. In 1997 he joined the faculty in the Department of Physics and Astronomy at the University of Georgia, where he is currently a Professor of Physics and a member of the Center for Simulational Physics. His interests include quantum computation and simulation.
February 08, 2024
NISQ Computing on a Complete Graph of Superconducting Qubits — Part II
Dr. Michael Geller
University of Georgia
Current quantum computing architectures lack the size and fidelity required for universal fault-tolerant operation, limiting the experimental implementation of key quantum algorithms to all but the smallest problem sizes. In this talk I’ll review the limitations of gate-based quantum computing with noisy intermediate-scale quantum (NISQ) processors, and introduce an alternative, non-gate-model approach that is ideally suited for today’s superconducting qubits. In this approach, computation is performed in the single-excitation subspace (SES) of a fully connected graph of n tunably coupled qubits. In contrast to the gate model, arbitrary nxn unitaries as well as controlled unitaries can be implemented in a constant number of steps. I’ll discuss the strengths and weaknesses of SES approach, and show an experimental demonstration of the technique applied to the simulation of high-temperature atomic collisions.
Dr. Michael Geller received his PhD in Physics from the University of California, Santa Barbara, in 1994. In 1997 he joined the faculty in the Department of Physics and Astronomy at the University of Georgia, where he is currently a Professor of Physics and a member of the Center for Simulational Physics. His interests include quantum computation and simulation.
February 15, 2023
Dynamic Conducting Polymer Nano-Optics
Linköping University
My group is interested in developing novel ways to control light and heat using organic materials like conducting polymers and cellulose. Applications include tuneable nanooptical metasurfaces, reflective color displays and energy-regulating optical materials. In this presentation, I will first focus on our work on conducting polymers as a new materials platform for dynamically tuneable plasmonics, as first demonstrated for nanostructures made from the highly conducting polymer PEDOT:Sulf.1 By contrast to static nanoantennas made of traditional metals, we show that the optical response of the polymeric antennas can be repeatedly turned off and on again by varying the redox state of the polymer, which reversibly switches the material between optically metallic and dielectric.1,2 Our latest work extends the topic to the organic semiconductor PBTTT and to excitonic materials.3,4 I will then demonstrate how the same type of conducting polymers offers novel means for forming structurally colored materials with dynamic coloration,5,6 with anticipated use for reflective labels and displays in color. Finally, I will discuss our latest work on radiative cooling by which thermal energy is transferred to space via Planck radiation, including electrical tuneability at ambient conditions.7-11
- Conductive polymer nanoantennas for dynamic organic plasmonics. S. Chen et al. Nature Nanotechnology 2020, 15, 35-40.
- Electrical Tuning of Plasmonic Conducting Polymer Nanoantennas. A. Karki et al. Advanced Materials 2022, 34, 13, 2107172
- Doped Semiconducting Polymer Nanoantennas for Tunable Organic Plasmonics. A. Karki et al. Communications Materials 2022, 2022, 3, 48
- Organic Anisotropic Excitonic Optical NanoantennasE. S. H. Kang et al. Advanced Science 2022, 9, 23, 2201907
- Dynamically tuneable reflective structural colouration with electroactive conducting polymer nanocavities. S. Rossi et al. Advanced Materials 2021, 33, 40, 2105004
- Tunable structural color images by UV-patterned conducting polymer nanofilms on metal surfaces. S. Chen et al. Advanced Materials 2021, 33, 33, 2102451
- Reflective and Transparent Cellulose-Based Passive Radiative Coolers. S. Gamage et al. Cellulose 2021, 1–11.
- Transparent nanocellulose metamaterial enables controlled optical diffusion and radiative cooling. S. Gamage et al. Journal of Materials Chemistry C 2020, 8, 11687-11694
- Structurally Colored Cellulose Nanocrystal films as Trans-Reflective Radiative Coolers. R. Shanker et al. ACS Nano 2022, 16, 7, 10156-10162
- Cellulose-based Radiative Cooling and Solar Heating Powers Ionic Thermoelectrics M. Liao et al. Advanced Science 2022, in press
- Electrical Tuning of Radiative Cooling at Ambient Conditions D. Banerjee et al. Cell Reports Physical Science, in press
march 01, 2023
Single Fluorescent Molecule Imaging
University of Georgia
Fluorescence microscopy is an essential tool in biological research. In this talk, I will discuss the imaging of single fluorescent molecules for high resolution localization of biological molecules and structures. I will cover new approaches that take advantage of quantum correlations to increase resolution, and I will cover recent work from my lab that uses holography of single molecules to achieve axial localization.
Dr. Kner received both his MS and PhD from UC Berkeley and has BS degrees in Physics and Electrical Engineering from MIT. He joined the University of Georgia in January 2009, after a postdoc in the Department of Biochemistry and Biophysics at the University of California, San Francisco (UCSF). At UCSF, he built microscopy systems for studying cellular sub-structure, making use of a variety of new technologies to improve imaging at the nanoscale in biomedicine and engineering. He built the first structured illumination microscope (SIM) fast enough to image living cells, working with Mats Gustafsson, a leader in the field of high resolution microscopy. He has five US patents for his inventions and was awarded the prestigious NSF Career Award in 2014.
March 22, 2023
University of Georgia
March 29, 2023
Interlayer excitons in graded alloys of MoxW1-xS2 monolayers
Mahdi Ghafariasl
University of Georgia
We employed an additive-assisted synthesis technique to prepare single-crystalline monolayers of alloyed MoxW1-xS2 and investigated their optical properties at the nanoscale. The monolayer has a tunable band gap in a broad range of 1.70–2.05 eV displaying prominent variation in sulfur composition from the center to the edge regions. The existence of excitons, trions, and defect-bound excitons is investigated using power-dependence and temperature dependent (4−300 K) photoluminescence spectroscopy. Detailed analysis of the alloyed monolayer reveals evidence of new types of defect-bound excitons originating at low temperatures compared to pristine MoS2 and pristine WS2.
April 05, 2023
Critical Points of Relativistic Quantum Field Theories on Current Quantum Hardware
Shane Thompson, University of Tennessee, Knoxville
Sarabpreet Singh, University of Georgia
April 12, 2023
Experimentally Realizable Continous-variable Neural Networks
Shikha Bangar & Leanto Sunny
University of Tennessee, Knoxville
April 19, 2023
Quantum Computing with Two-dimensional Conformal Field Theories
Elias Kokkas & Noah Crum
University of Tennessee, Knoxville
April 26, 2023
Asymmetric measurement-device-independent (MDI) quantum key distribution (QKD) in turbulent channels
MD Mehdi Hassan & Kazi Reaz
University of Tennessee, Knoxville
May 03, 2023
Non-Abelian Anyons with Rydberg Atoms
University of Tennessee, Knoxville
Fall 2023
The Fall 2023 Quantum Information Virtual Seminar Series will be held every Wednesday at 3PM. The meeting time might vary for speakers from different time zones. The seminars can be accessed via Zoom.
September 06, 2023
Many-Body Localization for Decoherence Protected Quantum Memory
Dr. Evangelos Varvelis
University of Ulm
Despite recent strides in quantum information, scalability is still hindered by decoherence, a phenomenon closely related to the thermalization of quantum systems. We will demonstrate that disordered transmon arrays experience a thermal to many-body localized phase transition using established diagnostics of spectral statistics. To reinforce our findings we will also introduce a new tool – the Walsh-Hadamard coefficients. Remarkably, even disorder-free systems can achieve MBL using quasi-periodic qubit frequency patterns. We studied this possibility using a perturbation theory scheme suited for large transmon arrays, bridging the gap between theory and experimentally relevant system sizes.
September 13, 2023
Quantum Sensing
Dr. Claire Marvinney
Oak Ridge National Laboratory
Quantum sensing incorporates a broad range of applications, from single photon emission and detection in a discrete variable system, to squeezed light emission and detection in a continuous variable system. For the first half of my talk, I will discuss single photon detectors, which are essential to fundamental tests of entanglement distribution and to applications in quantum networking, quantum computing, and quantum sensing. I demonstrate that superconducting nanowire single photon detectors (SNSPDs) have a position sensitivity to the signal readout pulse that is consistent with a simple model of microwave propagation along the length of the nanowire, and that SNSPDs can operate robustly under large magnetic fields and have the potential to be used as a multifunctional quantum sensor. In the second half of my talk, I will discuss the development of a continuous variable squeezed light source, which enables entanglement generation and quantum noise reduction, which are key components to continuous variable quantum sensing, networking, and computing. The quantum noise is reduced, or “squeezed”, in this light source because the noise in one variable of the optical field is reduced at the expense of the noise in the conjugate variable, thus enabling detection of previously unresolvable signals, with a current target of magneto-optical materials characterization, and a long-term target of dark matter detection.
September 27, 2023
From Wavefunction Collapse and Galois to Non-Abelian Anyons in a Quantum Device
Dr. Ruben Verresen
Harvard University
The rapid development of quantum devices—such as cold atoms, ions, superconducting qubits—are an invitation to explore exotic many-body states with a degree of control which was hitherto inaccessible. In this talk, I will discuss recent theoretical insights and experimental realizations of long-range entangled quantum states, with a focus on topological order. These phases of matter have been studied for decades due to their rich emergent properties, such as quasiparticles with ‘anyonic’ exchange statistics. Although these are challenging to create and verify in conventional quantum materials, we will see how they can be efficiently prepared using controlled quantum measurements. A particular highlight will be our recent collaboration with the cold-ion company Quantinuum, leading to the first realization of non-Abelian topological order—its anyonic braiding properties going beyond what is accessible in Abelian states such as the toric code. More broadly, we argue that the efficiently preparable states are related to Galois’ notion of solvable groups.
October 04, 2023
Noise in Quantum Computing
Dr. Samudra Dasgupta
University of Tennessee, Knoxville
Quantum computing’s potential is immense, promising super-polynomial reductions in execution time, energy use, and memory requirements compared to classical computers. This technology has the power to revolutionize scientific applications such as simulating many-body quantum systems for molecular structure understanding, factorization of large integers, enhance machine learning, and in the process, disrupt industries like telecommunications, material science, pharmaceuticals and artificial intelligence. However, quantum computing’s potential is curtailed by statistical uncertainties introduced by noise, further complicated by non-stationary noise parameter distributions across time and qubits. I will talk about the persistent issue of noise in quantum computing. In particular, the definitions of computational accuracy, device reliability, outcome stability, and result reproducibility, crucial for assessing noisy quantum outputs. By studying non-stationary noise in current quantum computers, I will stalk about a statistical framework to differentiate and analyze these concepts, delving into their nuanced interrelationships.
October 11, 2023
Hierarchical Quantization and Nearly Singular Superconducting Circuits
Dr. David DiVincenzo
Forschungszentrum Jülich & RWTH Aachen
In the analysis of superconducting qubits, the mathematical description of an electrical network appear to require models that lead to singular Lagrangians, describing constrained systems in which not all variables are independent. A procedure due to Dirac and Bergmann is commonly used to derive the Hamiltonian of such constrained electrical networks. But real electric networks are never singular, but rather have a hierarchy of scales. From this hierarchical point of view, we show that a correct treatment of the low-energy dynamics is obtained from a Born-Oppenheimer approach. We show that the Dirac-Bergmann approach gives completely incorrect answers, explaining this as this approach’s neglect of quantum fluctuations.
October 18, 2023
Old Tricks for New Quantum Cats
Dr. Eugene Dumitrescu
Oak Ridge National Laboratory
TBA
October 25, 2023
Quantum Error Correction in Superconducting Quantum Information Processors
ETH Zurich
TBA
November 01, 2023
Demonstrating a Long-Coherence Dual-Rail Erasure Qubit using Tunable Transmons
Dr. Harry Levine
Amazon
Quantum error correction with erasure qubits promises significant advantages over standard error correction due to favorable thresholds for erasure errors. To realize this advantage in practice requires a qubit for which erasure errors are the dominant error, and the ability to check for erasure errors without dephasing the qubit. We demonstrate that a “dual-rail qubit” consisting of a pair of resonantly-coupled transmons can form a highly coherent erasure qubit, where transmon T1 errors are converted into erasure errors and residual dephasing is strongly suppressed, leading to millisecond-scale coherence within the qubit subspace. We show that single-qubit gates are limited primarily by erasure errors while the residual error rates are ~ 40 times lower. We further demonstrate mid-circuit erasure detection while introducing < 0.1% dephasing error per check. Finally, we show that the suppression of transmon noise allows this dual-rail qubit to preserve high coherence over a broad tunable operating range, offering an improved capacity to avoid frequency collisions. This work establishes transmon-based dual-rail qubits as an attractive building block for hardware-efficient quantum error correction.
November 15, 2023
Collaboration Journey Maps: Road to Successful Scientific Collaborations
Dr. Mehmet Aydeniz
University of Tennessee, Knoxville
The increasing complexity of scientific, technological and social problems calls for knowledge, expertise and methodological collaboration across disciplines, yet scientists rarely receive training on scientific collaborations. As a result, most scientists do not know how to effectively collaborate across disciplinary, institutional and geographic boundaries. The factors that contribute to a scientist’s collaboration success are diverse ranging from attitudes towards collaboration to, the nature of collaboration task and institutional support for collaboration. All of these factors impact the ways in which a scientists engage in a collaboration across disciplinary, institutional and geographic boundaries. Dr. Aydeniz will cover best practices in and challenges associated with scientific collaborations in this talk. He will also introduce the Scientific Collaboration Journey Maps, a tool he has developed to guide scientific groups interested in forming, and sustaining effective scientific collaborations.
November 29, 2023
Verifiable Quantum Supremacy: What I Hope Will Be Done
University of Texas, Austin
I’ll advocate a research agenda for designing quantum computations that are (1) feasible on near-term, non-error-corrected, “NISQ” devices, (2) hard to simulate classically, and (3) easy to verify classically, where right now we only have any two of the three. The agenda involves understanding the structure of otherwise-random quantum circuits that have been postselected to have the behavior that we want (such as producing verifiable outputs). It includes concrete open problems on which progress seems feasible.
December 06, 2023
Secure Key Distribution for Quantum Network
University of Tennessee, Knoxville
Quantum Key Distribution (QKD) offers absolute security for distributing encryption keys between two parties against eavesdropping by relying on the principles of quantum mechanics. Since the proposal of the very first quantum key distribution by Charles H. Bennett and Gilles Brassard in 1984 (BB84), numerous improvements have been made to this kernel, enabling its transition from theory to practical use. The “complete” quantum network comprises multiple quantum nodes interconnected via secure quantum channels, with information being transmitted using ‘qubits’ rather than traditional bits. This week, I will discuss several experimental studies that explore the application of QKD in quantum networks.
Fall 2022
The Fall 2022 Seminar Series is in Nielsen Physics Bldg, Room 307 at the University of Tennessee at 3 pm on Wednesdays.
The seminars are also available via zoom.
August 31, 2022
Toward Quantum Cryptography Anywhere: Mitigating Atmospheric Turbulence
Cable Labs
September 07, 2022
CMOS Based Slilicon Photomultipliers
University of Tennessee, Knoxville
Silicon photomultipliers or SiPMs are optical detection devices which can replace traditional photomultiplier tubes, charge coupled devices, and active pixel sensor based imagers. They are especially important in optical quantum systems where sensitive optical detectors are needed. In this talk we discuss SiPMs which have been developed based on novel perimeter gated single photon avalanche diodes (PGSPAD) in standard commercial CMOS processes. We will also discuss the various readout and optimization strategies employed in developing optical detection systems.
September 14, 2022
Continuous Variable Quantum Machine Learning
MITRE
Machine learning is one of the most prominent application areas of quantum information science. Most of the proposed quantum machine learning tools have been offered so far are based discrete variable quantum computing model. However, generalization of the quantum machine learning tools to infinite dimension is important since some datasets have large variables that are not binary. To this end, continuous variable quantum computing (CVQC) model has been utilized and CV model of quantum machine learning have been proposed. In CVQC the information is encoded into quantum states of fields hence photonic hardware is a natural platform for realization of CVQC. This talk will review the recent advancements in CV quantum machine learning tools, and their implementability on the current quantum hardware.
Dr. Kübra Yeter-Aydeniz is a quantum algorithm specialist at MITRE Corporation. She received her PhD on theoretical high energy physics at the University of Tennessee, Knoxville. She then completed her postdoctoral research at Oak Ridge National Laboratory where she studied quantum simulation of quantum many body systems on near term quantum computers. Her current research includes studying continuous variable machine learning models, benchmark development for near term quantum hardware.
September 21, 2022
Entanglement of Fermions After an Interaction Quantum Quench
University of Tennessee, Knoxville
Following a sudden change of interactions in an integrable system of one-dimensional fermions, we analyze the growth and eventual asymptotic long-time value of the entanglement entropy under a spatial bipartition after the quantum quench. At small waiting times after the quench, we map the system to non-interacting bosons such that we are able to extract their occupation numbers from the Fourier transform of the density-density correlation function, and use these to compute a bosonic entropy from a diagonal ensemble. By comparing this bosonic entropy with the steady state entanglement entropy per fermion computed with exact diagonalization we find excellent agreement. These results open up a route to measuring entanglement in closed quantum systems of ultracold gases that only relies on the analysis of density-density correlations.
September 28, 2022
Machine learning for quantum computation and communication
Tulane University
We will discuss recent work involving the development and application of machine learning techniques to enhance various aspects of quantum computation on current, noisy quantum computers. In particular, we show the usefulness of machine learning in quantum state tomography and reconstruction. We will also discuss advances in enhancing free-space optical communication with machine learning, which we hope to extend into the quantum regime.
Professor Glasser received his Ph.D. in Physics from Louisiana State University, under the advisement of Prof. Jonathan Dowling, in 2009. He was then a researcher at Harris Corporation for 2.5 years, working experimentally on the DARPA Quantum Sensors program. In 2011 he was awarded National Research Council Postdoctoral Associateship at NIST and the University of Maryland. He was a postdoctoral researcher at NIST and UMD in Paul Lett and Bill Phillips’ Laser Cooling and Trapping Group, performing research in quantum information and quantum optics with warm atomic vapor, prior to joining the faculty at Tulane University in 2014. Since that time he has continued his research in experimental quantum optics and the use of machine learning in quantum information science.
October 5, 2022
Quantum Communications and Networking at Oak Ridge National Laboratory (ORNL)
Oak Ridge National Laboratory
Quantum networks are needed to harness the full promise of quantum devices. In this talk, we’ll introduce key concepts, devices, and systems for building quantum networks. We’ll describe how and why quantum key distribution is a great fit for energy infrastructure cybersecurity. And we will tie these themes to recent ORNL research.
October 12, 2022
High Fidelity Transmon Qubit Development at Chalmers University of Technology
Chalmers University of Technology
October 19, 2022
2022 NRT Annual Meeting, Blacksburg, VA
October 26, 2022
Architecture of a first-generation commercial quantum network
Dr. Duncan Earl
President & CTO, Qubitekk
The architecture and near-term use cases for a first-generation commercial quantum network will be presented. The foundational quantum hardware and software elements required to operate, manage, and configure the network for near-term consumer applications will be discussed. Recent efforts to implement this architecture with a commercial fiber optic network owner will be discussed.
Dr. Duncan Earl is the President and Chief Technology Officer at Qubitekk, Inc. Prior to co-founding Qubitekk, he spent eighteen years as an R&D scientist at Oak Ridge National Laboratory where he performed work in quantum optics, optical sensing, and various other optical research areas. Dr. Earl is a serial entrepreneur who has commercialized various technologies, holds numerous patents, and recently served as a Steering Committee member for the Quantum Economic Development Council (QED-C).
November 02, 2022
Towards Large-Scale Quantum Key Distribution Networks
Cisco
Packet-switching has been widely used in classical networking for its scalability and efficiency. Recently, we introduced packet-switching as a new paradigm in quantum networking. We propose a classical-quantum data frame structure and explore methods of frame generation and processing. Further, we present conceptual designs for a quantum reconfigurable optical add-drop multiplexer. As a near-term application, we discuss packet-switched quantum key distribution (QKD) networks, where QKD data are transmitted in hybrid data frame and the routing decisions are made in a decentralized fashion at individual routers. This approach could lead to a scalable QKD solution which can be integrated with classical communication networks.
November 09, 2022
Probing Interactions in Quantum Materials at the Nanoscale
University of Georgia
Interactions at the nanometer length scale give rise to intriguing phases in correlated quantum materials, lead to the design of exotic metamaterials, and offer enormous opportunities for the development of novel quantum technologies. In this talk, I will first introduce tip-based nanoscopy techniques for probing quantum materials and give examples of high-resolution probing of nanoscale phenomena and interactions in correlated oxides and van der Waals (vdW) crystals. Due to their highly tunable local optical and electronic properties correlated oxides provide exciting opportunities to reconfigure confinement and propagation of polaritons (hybrid strongly coupled light-matter quasiparticles) at the nanoscale[1,4-6]. I will introduce a hybrid polaritonic-oxide heterostructure platform consisting of vdW crystals, such as hexagonal boron nitride or alpha-phase molybdenum trioxide, transferred on nanoscale oxygen vacancy patterns on the surface of correlated perovskite oxides [1]. Hydrogenation, oxygen vacancies and temperature modulation allow spatially localized conductivity modulation of oxides nanoscale patterns, enabling robust real-time modulation and reconfiguration of polaritonic phenomena. Experimental work is supported by a simulational methodology that combines Langevin dynamics and Metropolis Monte Carlo methods [7]. Interaction of vdW crystals with oxygen and water in ambient environment lead to enhanced chemical reactivity of their extraordinarily high surface areas. Using a combination of hyperspectral photoluminescence, Raman and near-field nanoscopy I will present recent imaging and spectroscopy results that reveal exotic interface effects and oxidized species during photodegradation of atomic thick in-plane MoS2–WS2 heterostructures with nanoscale alloyed interfaces and thin flakes of allotropes of phosphorus (black and violet phosphorus)[2.3]. The 2D alloy interface coupled with intrinsic strain causes spatial inhomogeneity of the oxidation and emission of the various excitonic species, providing localized potential wells at corner interfaces for various charge carriers and enabling localized quantum emission with enhanced stability. References 1. N. A. Aghamiri, G. Hu, A. Fali, Z. Zhang, J. Li, S. Balendhran, S. Walia, S. Sriram, J. Edgar, S. Ramanathan, A. Alu, and Y. Abate, “Reconfigurable Hyperbolic Polaritonics with Correlated Oxide Metasurfaces” Nature Communications 13, Article number: 4511 (2022) , DOI: 10.1038/s41467-022- 32287-z 2. A. Fali, M. Snure, and Y. Abate, “Violet phosphorus surface chemical degradation in comparison to black phosphorus” Appl. Phys. Lett. (Editor’s Pick), 118, 163105 (2021) DOI: 10.1063/5.0045090 3. A. Fali, T. Zhang, J. Terry, E. Kahn, K. Fujisawa, S. Koirala, Y. Ghafouri, W. Song, L. Yang, M. Terrones, Y. Abate, Y. Abate, “Photo-degradation Protection in 2D In-Plane Heterostructures Revealed by Hyperspectral Nanoimaging: the Role of Nano-Interface 2D Alloys” ACS Nano 2021, 15, 2, 2447–2457 https://doi.org/10.1021/acsnano.0c06148 4. M. Kotiuga, Z. Zhang, J. Li, F. Rodolakis, H. Zhou, R. Sutarto, F. He, Q. Wang, Y. Sun, Y. Wang, N. A. Aghamiri, S. B. Hancock, L. P. Rokhinson, D. P. Landau, Y. Abate, J. W. Freeland, R. Comin, S. Ramanathan, and K. M. Rabe, “Carrier Localization in Perovskite Nickelates From Oxygen Vacancies” PNAS 201910490 (2019). https://www.pnas.org/content/116/44/21992 5. A. Fali, S. T. White, T. G. Folland, M. He, N. A. Aghamiri, S. Liu, J. H. Edgar, J. D. Caldwell ,R. F. Haglund, Y. Abate” Refractive Index-Based Control of Hyperbolic Phonon-Polariton Propagation” Nano Letters 2019 19 (11), 7725-7734 DOI: 10.1021/acs.nanolett.9b02651 6. T. G. Folland, A. F., S. T. White, J. R. Matson, S. Liu, N. A. Aghamiri, J. H. Edgar, R. F. Haglund Jr., Y. Abate, J. D. Caldwell, Reconfigurable infrared hyperbolic metasurfaces using phase change materials. Nature Communications 2018, 9. DOI: https://doi.org/10.1038/s41467-018-06858-y 7. S. B. Hancock, N. A. Aghamiri, D. P. Landau, and Y. Abate, “Langevin dynamics/Monte Carlo simulations method for calculating nanoscale dielectric functions of materials” PHYSICAL REVIEW MATERIALS 6, 076001 (2022), DOI:10.1103/PhysRevMaterials.6.076001
November 16, 2022
Hybrid Materials Systems for Quantum Computing and Networking Applications
Clemson University
Error-corrected quantum computing demands seamless integration of thousands of physical qubits. While superconducting qubits take the leading role in near-term quantum computing, their scaling is limited by the size of the comprising microwave components and cryostats that house them. This beckons extensive materials research to engineer platforms ideal for fault-tolerant and scalable quantum hardware. In this talk, I will provide an overview of the state-of-the-art for solid-state quantum hardware and the requirements to transition the field into the “Quantum Advantage” regime. I will then discuss different strategies to break through the existing scaling bottlenecks including voltage-tunable quantum devices and distributed scaling via optical-microwave transduction. All those strategies demand the realization of low-loss hybrid normal-superconductor materials systems ranging from superconductor-semiconductor to superconductor-piezoelectric oxides. With this approach, I hope to emphasize the significant role materials research plays in the development of emerging quantum technologies.
Kasra Sardashti is an Assistant Professor of Physics & ECE at Clemson University. His research group works on a number of projects focused on integrating hybrid systems into functional devices for quantum information processing, sensing, and communication. He is the lead PI of an NSF Quantum Interconnect Challenge Program (QuIC-TAQS) working on developing the first generation of quantum random access memories. He is also the recipient of the Powe Junior Faculty Enhancement Award offered annually by the Oak Ridge Associated Universities. Before joining Clemson, he served as a Research Scientist at NYU Center for Quantum Phenomena. He received his Ph.D. in Materials Science and Engineering from UC San Diego in 2016.
November 30, 2022
Examining topology and thermodynamics using current quantum computers
NC State University
Quantum hardware has advanced to the point where it is now possible to perform simulations of physical systems and elucidate their topological and thermodynamic properties, which we will discuss in this talk. I will give a brief introduction to quantum computing and why they might be useful tools for solving problems in condensed matter physics and beyond. Following that, I will present a perspective on thermodynamics of quantum systems ideally suited to quantum computers, namely the zeros of the partition function, or Lee-Yang zeros. We developed quantum circuits to measure the Lee-Yang zeros, and used these to reconstruct the thermodynamic partition function of the XXZ model. The calculations were run on a trapped ion quantum computer. The zeros qualitatively show the cross-over from an Ising-like regime to an XY-like regime, making this measurement ideally suitable in a current term quantum computing environment. If time permits, I will discuss our demonstration of how topological properties of physical systems can be measured on quantum computers. We leverage the holonomy of the wavefunctions to obtain a noise-free measurement of the Chern number, which we apply to an interacting fermion model.
December 07, 2022
Trapped Ions as a Platform for Quantum Computing, Simulation and Networking
University of Maryland
One of the most alluring promises of quantum devices is the ability to solve useful problems which are classically intractable. This quantum advantage has yet to be demonstrated, despite decades of theoretical and experimental work. While there is no doubt that quantum devices will need to improve in both operation fidelity and size, it is also possible that the method by which these programmable devices will be used to provide quantum advantage has not yet been theorized or vetted. In light of this, it is critical to use the small prototypes available now to develop the most experimentally efficient quantum protocols. In this talk, I will provide an overview of recent applications implemented on the trapped-ion quantum computing demonstrator device at the University of Maryland, explain the basic operation of quantum hardware based on trapped atomic ions, and summarize our progress in developing a quantum networking demonstrator device.