Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session M09: Progress Towards Quantum Memories: Quantum Memory, Networks and State Engineering |
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Chair: Philipp Preiss, Max Planck Institute of Quantum Optics Room: 206 D |
Wednesday, June 7, 2023 2:00PM - 2:12PM |
M09.00001: Ultra-Broadband, Low-Noise Quantum Memory in Atomic Barium Vapor with 95% Storage Efficiency Kai B Shinbrough, Benjamin D Hunt, Sehyun Park, Kathleen B Oolman, Tegan Loveridge, J. Gary Eden, Virginia O Lorenz Quantum memory bandwidth plays an important role in many quantum applications as it determines the pulse durations compatible with the memory and places an upper bound on the clock rate and processing speed of a quantum device. Here we present experimental results of an atomic barium quantum memory that enables storage and retrieval of ultra-broadband (>800 GHz) signal photons with high storage efficiency [95.6(3)%] and low noise [3.8(6) × 10−5 noise photons per pulse]. Our memory is unique in its high efficiency and simultaneously broad bandwidth, and its noise performance is comparable to state-of-the-art noise measurements in ladder-type atomic systems. |
Wednesday, June 7, 2023 2:12PM - 2:24PM |
M09.00002: Generating Graph States in an Array of Atomic Ensembles Eric S Cooper, Philipp Kunkel, Avikar Periwal, Monika H Schleier-Smith Graph states constitute a broad class of resource states with applications in quantum computation, simulation and metrology. Their generation demonstrates versatile control over the structure of entanglement in a quantum system. We generate graph states of atomic ensembles by combining two ingredients: local spin rotations and cavity-mediated all-to-all interactions. Using this general protocol, we alternatively localize entanglement within subsystems or enhance non-local entanglement to enable Einstein-Podolsky-Rosen steering between the two halves of our system. We further scale this protocol to generate a four mode square cluster state. We thus demonstrate programmable spatial entanglement and open the door to applications ranging from multimode quantum sensing to measurement based quantum computation. |
Wednesday, June 7, 2023 2:24PM - 2:36PM |
M09.00003: Entanglement-Optimal Trajectories of Many-Body Quantum Markov Processes Tatiana Vovk, Hannes Pichler We develop a novel approach aimed at solving the equations of motion of open quantum many-body systems. It is based on a combination of generalized wave function trajectories and matrix product states. We introduce an adaptive quantum stochastic propagator, which minimizes the expected entanglement in the many-body quantum state, thus minimizing the computational cost of the matrix product state representation of each trajectory. We illustrate this approach on the example of a one-dimensional open Brownian circuit. We show that this model displays an entanglement phase transition between area and volume law when changing between different propagators and that our method autonomously finds an efficiently representable area law unravelling. |
Wednesday, June 7, 2023 2:36PM - 2:48PM |
M09.00004: Effect of quantum statistics on computational power of atomic quantum annealers Yuchen Luo, Xiaopeng Li Quantum particle statistics fundamentally controls the way particles interact and plays an essential role in determining the properties of the system at low temperature. Here we study how the quantum statistics affects the computational power of quantum annealing. We propose an annealing Hamiltonian describing quantum particles moving on a square lattice and compare the computational performances of the atomic quantum annealers between two statistically different components: spinless fermions and hard-core bosons. In addition, we take an Ising quantum annealer driven by traditional transverse-field quantum fluctuations as a baseline. The potential of our quantum annealers to solve combinatorial optimization problems is demonstrated on random 3-regular graph partitioning. We find that the bosonic quantum annealer outperforms the fermionic case. The superior performance of the bosonic quantum annealer is attributed to larger excitation gaps and the consequent smoother adiabatic transformation of its instantaneous quantum ground states. Along our annealing schedule, the bosonic quantum annealer is less affected by the glass order and explores the Hilbert space more efficiently. Our theoretical finding could shed light on constructing atomic quantum annealers using Rydberg atoms in optical lattices. |
Wednesday, June 7, 2023 2:48PM - 3:00PM |
M09.00005: Fermionic State Engineering through Weak Measurement Yik Haw Teoh, Ian B Spielman, Hilary M Hurst Weak measurement enables the extraction of targeted information from a quantum system while minimizing decoherence due to measurement backaction. However, in many-body quantum systems, backaction from weak measurements can have novel effects on wavefunction collapse. We theoretically study continuously measured one-dimensional non-interacting fermions, starting in a ground-state Fermi sea. Repeated measurement of on-site occupation number drives the system from the completely delocalized Fermi sea toward a Fock state. We find that the spatial measurement resolution---in relation to the Fermi length---strongly affects both the collapse dynamics and the final state. We compare small-system exact numerical results to an analytical model and find that the quantum state undergoing measurement is described by a modified diffusion equation. These results indicate that weak measurement may be a powerful tool for state engineering in fermionic quantum systems. |
Wednesday, June 7, 2023 3:00PM - 3:12PM |
M09.00006: Deterministic and verifiable blind quantum computing with trapped ions Peter Drmota, David P Nadlinger, Dougal Main, bethan C nichol, Ellis Ainley, Dominik Leichtle, Chris J Ballance, Gabriel Araneda, Raghavendra Srinivas, David M Lucas Delegating quantum computations to a server usually comes at the cost of waiving privacy and security. Blind quantum computing addresses this issue through interactive protocols. |
Wednesday, June 7, 2023 3:12PM - 3:24PM |
M09.00007: A high-cooperativity cQED platform using a fiber cavity and individual atoms in tweezers Elmer Guardado-Sanchez, Brandon Grinkemeyer, Ivana Dimitrova, Danilo Shchepanovich, Eirini Mandopoulou, Vladan Vuletic, Mikhail D Lukin Neutral atom quantum processors can greatly benefit from integration with optical cavities. These optical interfaces can be used for fast readout for real time error detection and as a quantum networking node to entangle distant quantum processors. Here we present one candidate for such integration: a Fabry-Perot Fiber Cavity (FPFC). This system is compatible with optical tweezer arrays and enables strong coupling of multiple atoms with a single cavity mode. We cool and trap single atoms in optical tweezers above the FPFC and transport them into the cavity mode where we measure a single atom cooperativity of up to 75. We explore the capabilities of the platform with single and two-atom experiments, paving the way for integration of FPFCs with atom arrays for quantum computation, simulation, and networking protocols. |
Wednesday, June 7, 2023 3:24PM - 3:36PM |
M09.00008: Robust Quantum Memory in a Trapped-Ion Quantum Network Node Peter Drmota, Dougal Main, David P Nadlinger, Bethan C Nichol, Marius A Weber, Ellis M Ainley, Ayush Agrawal, Raghavendra Srinivas, Gabriel Araneda, Chris J Ballance, David M Lucas Quantum networks can revolutionise the way in which we distribute and process information. Applications in the fields of cryptography, quantum computing, metrology, and fundamental physics will require the ability to store entangled states while further entanglement is generated across the network. Trapped-ion nodes connected via photonic links are an excellent candidate for realising such networks. |
Wednesday, June 7, 2023 3:36PM - 3:48PM |
M09.00009: Optical time-frequency processor based on atomic quantum memory Mateusz Mazelanik, Adam Leszczynski, Michal Parniak Manipulation and detection of photonic spectro-temporal modes enable many quantum information protocols. The standard approach for spectro-temporal processing is to leverage space-time duality by employing electro-optic modulation combined with propagation through highly-dispersive fibers implementing a temporal imaging (TI) setup. A typical example is to perform a frequency-to-time mapping—a Fourier transform—that enables spectral measurements using time-resolving detectors. More advanced combinations of temporal and frequency modulations allow time-frequency mode-sorting that enables optimal filtering and spectral or temporal superresolution measurements. Such state-of-the-art solutions are all well suited for broadband (>100 GHz) systems, such as quantum dots or other solid-state-based setups. Feasible implementations of the protocols merging flexibility of atomic systems and temporal processing capabilities inherently require an ability to manipulate and detect temporal photonic modes with a spectral and temporal resolution matched to the narrowband atomic emission. We demonstrate a novel approach to spectro-temporal processing working in a previously unexplored regime of narrowband atomic emission. Our method is based on atomic gradient-echo quantum memory (GEM) for light that maps incoming light pulses onto atomic coherence—spin waves. We combine the GEM with a spin wave phase modulation caused by a programmable spatially varying light shift of the atomic levels used for the memory. We can imprint almost arbitrary phase profiles onto the coherence and for example, achieve an ultra-large group-delay dispersion for an optical pulse stored in the coherence. Combining this with a simple acousto-optic modulation, we implement far-field temporal imaging with <1 MHz bandwidth and a resolution of <20 kHz. Moreover, with a more advanced protocol, that combines TI with in-memory interference we are able to demonstrate a super-resolution spectrometer performing quantum-optimal measurement of the frequency difference between two emitters, achieving resolution way below the Fourier limit. |
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