Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session S71: Control of Quantum SystemsFocus
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Sponsoring Units: DQI Chair: Yiming Xu; Saeed Khan, Princeton University Room: Room 407/408 |
Thursday, March 9, 2023 8:00AM - 8:12AM |
S71.00001: Continuously tracked, stable, large excursion trajectories of dipolar coupled nuclear spins Ozgur Sahin, Hawraa Al Asadi, Paul M Schindler, Arjun Pillai, Erica de Leon Sanchez, Matthew L Markham, Mark Elo, Maxwell McAllister, Emanuel Druga, Christoph Fleckenstein*, Marin Bukov, Ashok Ajoy We report an experimental approach to excite, stabilize, and continuously track Bloch sphere orbits of dipolarcoupled nuclear spins in a solid. We demonstrate these results on a model system of hyperpolarized 13C nuclear spins in diamond. Without quantum control, inter-spin coupling leads to rapid spin decay in T2* ≈ 1.5ms. We elucidate a method to preserve trajectories for over T2’>27s at excursion solid angles up to 16°, even in the presence of strong inter-spin coupling. This exploits a novel spin driving strategy that thermalizes the spins to a long-lived dipolar many-body state, while driving them in highly stable orbits. We show that motion of the spins can be quasi-continuously tracked for over 35s in three dimensions on the Bloch sphere. In this time the spins complete >68,000 closed precession orbits, demonstrating high stability and robustness against error. We experimentally probe the transient approach to such rigid motion, and thereby show the ability to engineer highly stable “designer” spin trajectories. Our results suggest new ways to stabilize and interrogate strongly-coupled quantum systems through periodic driving and portend powerful applications of rigid spin orbits in quantum sensing. |
Thursday, March 9, 2023 8:12AM - 8:24AM |
S71.00002: Generation of genuine all-way entanglement in defect-nuclear spin systems through dynamical decoupling sequences Evangelia Takou, Edwin Barnes, Sophia Economou Creating electron-nuclear entanglement in defects is difficult as the always-on hyperfine interactions prohibit complete isolation of the target system from unwanted spins. We design sequential or single-shot entangling gates that prepare high-quality GHZM states with minimal cross-talk and within the coherence times. We verify genuine multipartite correlations through the all-way entangling power of the gates. We study the entanglement of mixed electron-nuclear states and develop a non-unitary M-way entangling power which captures correlations arising from spectator nuclei. |
Thursday, March 9, 2023 8:24AM - 8:36AM |
S71.00003: Quantum Control over Highly-Coherent Nuclear Spins William R Munizzi, William A Terrano, Christian Arenz, Keaten Wood Some of the most coherent quantum states ever produced, with N >1018 and lifetimes of 10,000 seconds, are ensembles of optically-pumped noble gas spins. We are working to maximize their sensing potential with quantum control techniques such as adaptive feedback optimal control and dynamical decoupling. Already, certain implementations provide the most sensitive absolute measurements of the energy splitting between quantum states, and have been used to measure fundamental physics. Such implementations are additionally being studied for advanced navigation and sensing purposes. Currently, these measurements are limited by non-linear interactions among the spins. The associated decoherence be overcome by application of decoupling pulses that suppress the time-average of the unwanted interactions, or by careful preparation of specific superposition states that are insensitive to problematic non-linearities. The complexity of the quantum control challenge is increased by the need to control multiple, spatially overlapping, spin ensembles. I will discuss our strategies, simulations and (possibly) experimental demonstrations of quantum control over these highly-coherent, spatially overlapped, systems. |
Thursday, March 9, 2023 8:36AM - 8:48AM |
S71.00004: Optimal quantum control of Si/SiGe spin qubits in a Quantum bus architecture Akshay Menon Pazhedath, Alessandro David, Felix Motzoi, Lars Schreiber, Hendrik Bluhm, Tommaso Calarco Quantum bus architecture based on electron spin-shuttling is a promising candidate for scalable quantum computing, as the number of control lines required to control the spin remains constant irrespective of the length of the device. A gated Si/SiGe quantum well with a carefully placed micro- magnet acts as an addressable qubit system in such an architecture. We investigate the feasibility of performing single qubit operations using optimal quantum control techniques. Spin decoherence due to interaction with the valley degree of freedom in the Si/SiGe heterostructure is identified as a potential decay mechanism and optimal pulses are engineered to maximize single qubit state transfer and unitary operation fidelities, so that the operations are compliant with the fault tolerant error threshold. |
Thursday, March 9, 2023 8:48AM - 9:00AM |
S71.00005: Robust Driving Scheme for Triggered Solid-State Quantum Light Sources: Notch-filtered Adiabatic Rapid Passage (NARP) Grant Wilbur, Ali Binai-Motlagh, Alison Clarke, Ajan Ramachandran, Nick Milson, John Healey, Sabine O'Neal, Dennis Deppe, Kimberley C Hall Single photon sources play a significant role in several emerging applications in the field of quantum information such as single photon quantum computing [1], and quantum-enhanced sensing and metrology [2]. The ideal quantum emitter would be based on a solid-state platform and produce single photons on-demand, with successive photons being indistinguishable in all degrees of freedom. To achieve the highest degree of indistinguishability, resonant pumping of the quantum emitter is required to eliminate incoherent relaxation pathways. This necessitates an efficient approach to filter the scattered excitation light from the single photon stream. We present a novel pumping scheme called NARP [3] which utilizes frequency-swept optical pulses containing a spectral hole resonant with the optical transition in the emitter. This scheme retains all the benefits of adiabatic rapid passage for pumping solid-state emitters including robustness to variations in the properties of emitters and the laser source as well as the ability to suppress decoherence tied to electron-phonon coupling. Our scheme would enable <10-8 scattered photons per emitted photon with only a 4% detection loss. We demonstrate quantum state inversion using NARP in a single semiconductor quantum dot. |
Thursday, March 9, 2023 9:00AM - 9:12AM |
S71.00006: Quantum State Driving along Arbitrary Trajectories Le Hu, Andrew N Jordan Starting with the quantum brachistochrone problem of the infinitesimal form, we solve the minimal time and corresponding time-dependent Hamiltonian to drive a pure quantum state with limited resources along arbitrary pre-assigned trajectories. It is also shown that out of all possible trajectories, with limited resources, which are physically accessible and which are not. The solution is then generalized to the mixed quantum state cases, and applied to trajectories parameterized by single or multiple parameters with discrete or continuous spectrum. We then compare the solution to that of counterdiabatic driving, and show how the Berry phase is directly involved in both driving processes. |
Thursday, March 9, 2023 9:12AM - 9:48AM |
S71.00007: Dominique SugnyProfessor of physicsLaboratoire Interdisciplinaire Carnot de Bourgogne, Université de Bourgogne9 Av. A. Savaray 21000 Dijon, FranceQuantum optimal control in Quantum Technologies Invited Speaker: Dominique Sugny We apply innovative tools coming from quantum control theory to improve theoretical and experimental techniques in quantum technologies. This approach allows us to explore and to experimentally reach the physical limits of the corresponding dynamics in the presence of typical experimental imperfections and limitations. After a pedagogical introduction to these techniques, different applications in quantum technologies will be described. Recent theoretical and experimental results will be presented. More generally, the different perspectives of quantum control for the development of quantum technologies will be also discussed. |
Thursday, March 9, 2023 9:48AM - 10:00AM |
S71.00008: Tight speed limits on two-qubit gates in a fully-connected quantum computer Casey W Jameson, Bora Basyildiz, Daniel Moore, Kyle Clark, Zhexuan Gong A quantum computer with fully connected qubits is expected to perform quantum algorithms involving remote |
Thursday, March 9, 2023 10:00AM - 10:12AM |
S71.00009: A classical Hamiltonian description of the quantum brachistochrone problem Savvas Malikis The quantum brachistochrone plays an important role in quantum control since it sets fundamental limits on the resources required to realize a quantum operation. |
Thursday, March 9, 2023 10:12AM - 10:24AM |
S71.00010: Nonlinear speed-ups in ultracold quantum gases Sebastian Deffner Quantum mechanics is an inherently linear theory. However, collective effects in many body quantum systems can give rise to effectively nonlinear dynamics. In the present work, we analyze whether and to what extent such nonlinear effects can be exploited to enhance the rate of quantum evolution. To this end, we compute a suitable version of the quantum speed limit for numerical and analytical examples. We find that the quantum speed limit grows with the strength of the nonlinearity, yet it does not trivially scale with the "degree'' of nonlinearity. This is numerically demonstrated for the parametric harmonic oscillator obeying Gross-Piteavskii and Kolomeisky dynamics, and analytically for expanding boxes under Gross-Pitaevskii dynamics. |
Thursday, March 9, 2023 10:24AM - 10:36AM |
S71.00011: Enhancing atomic dark matter and gravitational wave detectors with quantum optimal control Zilin Chen, Garrett Louie, Timothy Kovachy, Yiping Wang, Tejas Deshpande Large scale atom interferometers using strontium atoms are promising for searching for ultralight dark matter and gravitational waves in a currently unexplored frequency range. In atom interferometry, the atomic superposition states are created and controlled by transferring momentum from laser pulses. The interferometer sensitivity can be enhanced by implementing large momentum transfer (LMT) atomic beam splitters with hundreds or even thousands of pulses which drives atomic transitions between ground and excited states. Deviation from ideal transitions limit the control efficiency and lead to significant atom loss after numerous pulses. During the driving process, deviations can be induced by various factors such as location deviation of atoms in the cloud, non-zero initial velocity spread of atoms respective to the rest-frame, intensity, phase fluctuations and polarization aberration in the laser pulses, and non-zero environmental electromagnetic fields. We manage to drive transitions of the 87Sr atoms in simulation with high fidelity and shorter pulse duration by employing the quantum optimal control techniques which increase the robustness and efficiency of driving pulses against nonideal factors by detuning the amplitude and phase instantaneously and constantly in the pulse duration timescale. As a result, in our full interferometer simulation, the optimized pulse reveals big advantages over primitive and other composite pulses. |
Thursday, March 9, 2023 10:36AM - 10:48AM |
S71.00012: Development of Attosecond Cross-Correlator for Evaluation of High-Harmonic Generation zairui li, Sergio Carbajo, Wesley Sims It has been a challenge for time-resolved quantum physics to watch the ultrafast electrons transition from one constituent to another or the ejection of electrons from an atom or molecule. These higher-energy processes happen at attosecond timescales are increasingly relevant to a broad range of science and technology for the applications of quantum electrodynamics. Thus, development of a new capable time tool is in need. In this study we introduce an attosecond cross-correlator system for quantum electrodynamics namely Hyperspectral Attosecond Quantum X-correlator (HAQ-X). The system is based on a balanced optical cross-correlator (BOC) by analyzing a pair of femtosecond laser pulses with one encoded by high-harmonic frequency comb generated due to optically pumped quantum materials. Due to the work of BOC the sum-frequency intensity differences after double-path through nonlinear crystal, the amplitude differences indicate the temporal delay of the two wave packets. To measure physical phenomenon with HAQ-X, we are investigating one type of ultrafast electronic dynamics that evolves with electron ionizations in a strong field leads to high-harmonic generation (HHG) process. The frequency comb will have attosecond temporal features to challenge our capabilities. Capturing temporal information of HHG can provide a new understanding of HHG via quantum mechanics. This could lead to new possibilities of generating paired photons in a strong field or entanglements at high photon energy level. Theoretical modeling of the HAQ-X system is developed to determine the temporal sensitivity, by applying the properties of known quantum material that generates high order harmonics such as Single- or double-layers Graphene, ZnO, MoS2, and Cd3As2. Simulation results of HAQ-X system outputs a 0.02 to 10 pW/attosecond sensitivity level. The operation mechanism of HAQ-X provides resilience in noise and time jitter, makes it a robust and cost-efficient time tool that allows us to analysis ultrafast electrodynamics and unveil new physics. |
Thursday, March 9, 2023 10:48AM - 11:00AM |
S71.00013: Co-design of quantum devices with optimal control Nicolas Wittler, Shai Machnes, Frank Wilhelm-Mauch The practical application of quantum computing and the research into qubit and device designs are often separate fields. When exploring operating regimes for quantum devices, often specific properties like noise resistance are selected based on previous experience or intuition, resulting in designs like the Transmon and the Fluxonium. In the current NISQ era, there is a demand for functional quantum devices to solve relevant computational problems, which motivates a more utilitarian perspective on device design: The goal is to have a device that is employed to run a given algorithm with state-of-the-art performance. |
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