CAMPUS CLOSED, EVENT POSTPONED

Physics Colloquium, CTLM 102 from 4:00 PM to 5:00 PM

Calendar Entry

no seminar

Physics Colloquium, CTLM 102 from 4:00 PM to 5:00 PM

Calendar Entry

TBD

Join us in Library 121, or on Zoom, for this livestreamed talk.
Join as an attendee from PC, Mac, Linux, iOS or Android: https://mines.zoom.us/j/98804513801?pwd=TlRqWUVwVTAxdk9DUDVRZEswanZ4QT09; Password: 504387

TBD

Physics Colloquium, CTLM 102 from 4:00 PM to 5:00 PM

no seminar

 no seminar

Considerable investment has been made recently in the development of quantum computers and quantum networks, with bold claims that they will permanently change our industry, economy, and society. How soon will that happen, or will it ever happen? The first half of this talk will describe how quantum computers and networks are fundamentally different from their classical counterparts. The unique challenges posed by their development will be highlighted and a realistic view of current technology and how far it has to go will be presented. The second half of the talk will describe an ambitious effort at NIST to create the optical distribution of remote microwave entanglement for the networking of superconducting quantum computers. With a continuous variables approach, two-mode squeezed optical states are used as the entanglement resource while vibrating membrane devices perform the microwave-optical transduction. Colorful results from the lab will be shared.

Join us in Library 121, or on Zoom, for this hybrid (talk will be given in person and livestreamed) event.
Join as an attendee from PC, Mac, Linux, iOS or Android: https://mines.zoom.us/j/98804513801?pwd=TlRqWUVwVTAxdk9DUDVRZEswanZ4QT09; Password: 504387

Jiaqi (Jimmy) Leng

Abstract: Continuous optimization problems arise in virtually all disciplines of quantitative research, including applied mathematics, computer science, and operations research. While convex optimization has been well studied in the past decades, nonconvex optimization generally remains intractable in theory and practice. Quantum computers, an emerging technology that exploits quantum physics for information processing, could pave an unprecedented path toward nonconvex optimization.

This talk focuses on Quantum Hamiltonian Descent (QHD), a recently proposed quantum algorithm for continuous optimization. QHD is derived as the path integral of standard gradient descent (GD). It inherits the algorithmic simplicity of GD and meanwhile exhibits a drastically different behavior from GD due to the quantum interference of classical paths, especially for nonconvex optimization. Specifically, we prove that QHD can efficiently solve a family of nonconvex continuous optimization instances, each characterized by exponentially many local minima. The new mathematics of QHD, including a surprising connection between QHD and Wasserstein geometry, is yet to be understood. Beyond the standard circuit-based implementation, we also propose an analog implementation of QHD through the Hamiltonian embedding technique for sparse Hamiltonian simulation. Based on this approach, we develop an open-source software named QHDOPT, which is used in an empirical study to confirm the practical advantage of QHD for large-scale nonconvex problems.

Bio: Jiaqi Leng is a fifth-year doctoral student at the University of Maryland, advised by Dr. Xiaodi Wu. His research focuses on quantum algorithms and scientific computing. In particular, he tries to bridge the gap between the theoretical foundations of quantum computing and the limitation of realistic quantum hardware in the near term. He will join UC Berkeley as a Simons Quantum Postdoctoral Fellow in the fall of 2024.

Join us in Library 121, or on Zoom, for this livestreamed talk.
Join as an attendee from PC, Mac, Linux, iOS or Android: https://mines.zoom.us/j/98804513801?pwd=TlRqWUVwVTAxdk9DUDVRZEswanZ4QT09; Password: 504387

no seminar

Mines Quantum Week Schedule

• Monday, April 15^th– Quantum Talks by fellow students (TBA)
  • When: 12:15pm – 1:45pm
  • Where: Berthoud Hall 243
• Monday, April 15^th– Beginner Quantum Coding Workshop
  • When: 3:30pm – 4:30pm
  • Where: Marquez Hall 126
• Tuesday, April 16^th– Quantum Information Seminar by Jiaqi Leng, University of Maryland, College Park, Quantum Approach to Classical Optimization: Why Bother and What to Do? Abstract given in the Quantum Information Seminar section on this page.
  • When: 10:00am – 10:50am
  • Where: Library 121 or on Zoom
• Wednesday, April 17^th– Quantum Week Keynote: We are excited to share that our keynote presentation will be given by Dr. Zhexuan Gong, Exploring novel quantum phases with trapped-ionquantum simulation. Flyer
  • When: 12:30pm – 1:30pm
  • Where: McNeil Hall 213
  • Abstract: Trapped-ion based quantum simulators have a unique strength of simulating interacting spin models with tunable, long-range interactions. With individual control and measurement of the ion qubits, one can demonstrate a variety of novel quantum phases, both in and out of equilibrium, that only exist in the presence of sufficiently long-range interactions. As an example, I will describe our recent collaborative effort in observing a continuous symmetry breaking phase with a chain of up to 23 trapped ions. Such a phase has not been observed before in any one-dimensional spin system. In the second half of the talk, I will propose new trapped-ion experiments for studying steady-state phase transitions with long-range interactions that have no analog in thermal equilibrium. Strong signatures of such non-equilibrium dissipative phase transitions can be observed within the reach of current experiments.
• Wednesday, April 17^th– Advanced Quantum Coding Workshop
  • When: 3:30pm – 4:30pm
  • Where: Hill Hall 204
• Thursday, April 18^th– Journal Club
  • When: 10:00am
  • Where: CoorsTek 230
  • What: Select an article that you feel has made a major contribution to quantum information technologies. Come prepared to share your thoughts on the following:
    • Why is it important, and what are its implications to the field?
    • Which work builds upon it?
    • How would you design a project to get hands-on experience with the topics in the article
• Friday, April 19^th– Quantum Week Closing Banquet
  • When: 3:00pm – 4:00pm
  • Where: Marquez Hall 126

Superconducting technologies have been developed and employed with great success by the quantum information science community.
More and more, these technologies show promise for fundamental physics. I want to sketch some of their possible advantages in the context of the Ricochet and Project 8 neutrino experiments.

Project 8 aims to measure the neutrino mass using the observation of cyclotron radiation from tritium decay electrons. To collect and detect this attowatt power signal, we investigate the quantum-limited readout of resonant cavities using Travelling Wave Parametric Amplifiers (TWPA) at MIT. These amplifiers are appropriate for broadband microwave amplification with a high dynamic range that could suit both Project 8 and Ricochet.

The Ricochet experiment aims to detect coherent elastic neutrino-nucleus scattering at the nuclear research reactor in Grenoble, France. The experiment will start data-taking in 2024 with two complementary detector technologies, both employing cryogenic calorimeters.

One of the two detector technologies envisaged by Ricochet has a target mass consisting of superconducting crystals. When a neutrino interacts coherently with a nucleus in a superconducting crystal lattice, the recoil energy produces phonons and excites cooper pairs into Bogoliubov quasiparticles. The milli-electronvolt-scale bandgap of superconductors might enable a significantly lower nuclear recoil energy threshold. To sense the energy in the phonon and quasiparticle systems, a trapping and thermalisation layer is connected with transition edge sensors for ultra-sensitive heat to current conversion. Several detectors are envisaged to be frequency multiplexed into the microwave band using SQUIDs and resonators at cryogenic temperatures.

Physics Colloquium, CTLM 102 from 4:00 PM to 5:00 PM

Exponential Quantum Advantage in Approximate Optimization of Hard Constraint Satisfaction Problems

Abstract: A huge range of important problems in computer science–including task optimization, formal logic, encryption, and machine learning–can be solved by finding the sequence of binary variables that optimizes a cost function defined by a series of few-variable constraint relationships. Many of these problems are in the complexity class NP, and are in the worst case, and often the typical case, exponentially hard in the number of variables for all known methods. This hardness applies both to exact and approximate optimization, e.g. finding configurations with a value within a defined fraction of the global optimum. Fundamentally, the lack of any guided local minimum escape method ensures the hardness of both exact and approximate optimization classically, but the intuitive mechanism for approximation hardness in quantum algorithms based on Hamiltonian time evolution is not well understood. In this work, using the prototypically hard MAX-3-XORSAT problem class, we explore this question. We conclude that the mechanisms for quantum exact and approximation hardness are fundamentally distinct. We qualitatively identify why traditional methods such as high depth quantum adiabatic optimization algorithms are not reliably good approximation algorithms. We propose a new spectral folding optimization method that does not suffer from these issues and study it analytically and numerically. We consider random rank-3 hypergraphs including extremal planted solution instances, where the ground state satisfies an anomalously high fraction of constraints compared to truly random problems. We show that, if we define the energy to be E = N_unsat-N_sat, then spectrally folded quantum optimization will return states with energy E ≤ AE_GS (where E_GS is the ground state energy) in polynomial time, where conservatively, A ≃ 0.6. We thoroughly benchmark variations of spectrally folded quantum optimization for random classically approximation-hard (planted solution) instances in simulation, and find performance consistent with this prediction. We do not claim that this approximation guarantee holds for all possible hypergraphs, though our algorithm’s mechanism can likely generalize widely. These results suggest that quantum computers are more powerful for approximate optimization than had been previously assumed.

The preprint on this is on arxiv: https://arxiv.org/abs/2312.06104

Calendar Entry

Physics Colloquium, 02/22. Marquez 235, 11:00 AM – 12:00 PM

Revealing Unknown Nuclear Properties with Next-Gen Precision Technique

Radioactive ion beam facilities offer unique access to unexplored regions of the nuclear chart. Due to short half-lives and low production yields of the most promising regions of the nuclear chart, next-generation high-precision techniques are crucial for characterizing fundamental nuclear properties. This talk presents recent developments in ion trapping and laser spectroscopy techniques of radioactive isotopes that have enabled pioneering precision measurements of neutron-rich indium isotopes in the direct vicinity of the doubly-magic 100Sn(N=Z=50) at CERN/ISOLDE. Using precision mass measurements, we resolved a discrepancy in the β-decay energy of 100Sn, thereby providing an updated atomic mass value for 100Sn via its direct β-decay into 100In [Nature Phys. 17, 1099 (2021)]. Furthermore, using precision laser spectroscopy of the same indium isotopes, we shed light on 100Sn’s doubly magic character through the evolution of nuclear deformation across the indium isotopic chain. [arXiv:2310.15093; under review with Nature Phys.] The impact of these measurements is further demonstrated through an assessment of state-of-the-art density-functional and ab initio nuclear theory approaches. Lastly, I will introduce a new experiment in which both techniques are combined into a quantum-sensing setup capable of precision measurements of fundamental symmetries and unknown effects of the nuclear electroweak structure [arXiv:2310.11192; under review with Phys. Rev. Lett.]. In particular, utilizing a two-level superposition in single trapped molecular ions allows for vast amplification of unknown parity-violating effects such as the nuclear anapole moment. The tremendous leverage offered by radioactive molecules is discussed.

Bio
Undergraduate research at the Max-Planck-Institute for Nuclear Physics in trapped cluster research under Prof. Klaus Blaum
Master’s and doctorate research at CERN’s radioactive ion beam facility ISOLDE in precision mass spectrometry also under Prof. Klaus Blaum
Implemented the next-generation mass spectrometry technique called “phase-imaging” and employed in exotic isotopes around 100Sn and 132Sn
Graduated “Summa Cum Laude” in only 2.5 yrs (50% German average) and awarded with three dissertation awards: Heidelberg University, German Physical Society, European Physical Society
Postdoctoral research at MIT in precision laser spectroscopy of radionuclides under Prof Ronald Garcia Ruiz
Key person to build new laser spec setup at the new FRIB facility at MSU with three accepted proposals as spokesperson
Awarded with Humboldt Research Fellowship and Young Scientist Award of GSI facility to create and lead a new quantum-sensing experiment to study fundamental symmetry violation and electroweak effects.

Computer Science Seminar, 02/22. Marquez 222, 4:00 PM – 5:00 PM

Physics Colloquium, 02/26, Berthoud Hall 241, 4:00 PM – 5:00 PM

Individual Rare Earth Ions in Nanophotonic Structures for Quantum Networks Applications

Abstract: Single erbium ions in crystalline hosts are attractive candidates for solid-state spin-photon interfaces thanks to long-lived spin states and optical transitions in the telecom band, promising a clear advantage for long-distance quantum network applications. These ions can be incorporated into a wide range of host materials, which influence their spin and optical coherence properties through the concentration of other magnetic spins and the erbium site symmetry. Using silicon photonic crystal cavities, we can isolate single erbium ions and investigate their optical and spin properties using resonance fluorescence and optically detected magnetic resonance. In this talk, I will show our recent work on erbium ions implanted into CaWO4, which enabled the observation of the high indistinguishability of subsequently emitted photons in the Hong-Ou-Mandel experiment [1]. This represents a notable step towards the construction of telecom band quantum repeater networks with single erbium ions. I will also discuss our recent progress on generating spin-photon and spin-spin entanglement.
[1] S. Ourari*, Ł. Dusanowski*, S.P. Horvath*, M.T. Uysal*, C.M. Phenicie, P. Stevenson, M. Raha, S. Chen, R.J. Cava, N.P. de Leon, and J.D. Thompson, Indistinguishable telecom band photons from a single Er ion in the solid state, Nature 620, 977 (2023).

Bio: Lukasz Dusanowski is an Associate Research Scholar at the Department of Electrical and Computer Engineering at Princeton University. He obtained his Ph.D. in Physics at Wroclaw University of Science and Technology in Poland. Before joining Princeton, he was a Humboldt postdoctoral fellow at the University of Wurzburg in Germany, where he worked on developing different single photon emitter platforms integrated with on-chip photonic circuits. Currently, his research is focused on utilizing rare earth ion dopants in crystalline hosts as single photon sources and quantum memories for quantum network applications.

Physics Special Colloquium, 02/29, Berthoud Hall 241, 4:00 PM – 5:00 PM

DR. LAURA KIM

Nanophotonic Interfaces to Control Plasmons and Spins for Next-Generation Quantum Technologies

Abstract: Light-matter interactions mediated by photonic quasiparticles play a crucial role in unlocking phenomena that are not accessible with free-space photons and providing efficient interfaces for quantum systems. In the first part of the presentation, I will present the first experimental demonstration of a mid-infrared light-emitting mechanism originating from an ultrafast coupling of optically excited carriers into hot plasmon excitations in graphene. Such excitations show gate-tunable, non-Planckian emission characteristics due to the atom-level confinement of the electromagnetic states. These findings for plasmon emission in photo-inverted graphene open a new path for the exploration of mid-infrared emission processes, and this mechanism can potentially be exploited for both far-field and near-field applications for strong optical field generation. In the second part of the presentation, I will present a resonant metasurface that mediates efficient spin-photon interactions and enables a new type of quantum imaging hardware. This quantum metasurface containing nitrogen-vacancy (NV) spin ensembles coherently encodes information about the local magnetic field on spin-dependent phase and amplitude changes of near-telecom light. The central challenge with NV sensing remains in suboptimal optical readout due to the inefficient spin-photon interface, limiting its achievable sensitivity. In this presentation, I will discuss that nanophotonic strategies provide opportunities to achieve near-unity optical spin readout fidelity for absorption-based readout. This resonant surface is designed to readily couple with external radiation and allow shot-noise-limited sensing with a standard camera, eliminating the need of single-photon detectors. This quantum optical imaging system paves the way for a new type of quantum micro(nano)scopy. The projected performance makes the studied quantum imaging metasurface appealing for the most demanding applications such as imaging through scattering tissues and spatially resolved chemical NMR detection.

Biography: Laura Kim is an assistant professor in the Department of Materials Science and Engineering at UCLA. Prior to joining UCLA, she completed her IC Postdoctoral Fellowship in the Quantum Photonics Laboratory at the Massachusetts Institute of Technology. She received her B.S. and Ph.D. degrees from the California Institute of Technology. She was named a 2020 EECS Rising Star and a recipient of the IC Postdoctoral Fellowship, Gary Malouf Foundation Award, and National Science Foundation Graduate Research Fellowship. She serves on the Early Career Editorial Advisory Board of Applied Physics Letters. Her current research interests include enhancing photonic-quasiparticle-driven light-matter interactions and developing nanoscale quantum sensing technologies.

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