Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session P31: Hybrid Quantum Systems IIILive
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Sponsoring Units: DQI DAMOP Chair: Sara Mouradian, UC Berkeley |
Wednesday, March 17, 2021 3:00PM - 3:12PM Live |
P31.00001: Toward a Graphene-based Quantum Simulator Phillip Weinberg, Adrian Feiguin We propose an architecture that allows for the systematic control of the effective exchange interactions between magnetic impurities embedded in nano-scale graphene flakes connected by a gated bridge. The entanglement between the magnetic moment and the edge states of the fragments is used to electrostatically tune the exchange interaction from ferro to antiferromagnetic by merely changing the bridge's carrier density. By characterizing the effects of size and coupling parameters, we explore different operation regimes of this device employing exact calculations with the density matrix renormalization group. We analyze the results utilizing a simplified model that accounts for the main many-body mechanisms. Finally, we discuss how to use arrays of these devices to build quantum simulators for quantum many-body Hamiltonians. |
Wednesday, March 17, 2021 3:12PM - 3:24PM Live |
P31.00002: Improving cooling performance in an optomechanical system using a non-linear cavity David Zoepfl, Mathieu L. Juan, Christian M. F. Schneider, Gerhard Kirchmair The possibility to operate massive mechanical resonators in the quantum regime has become central in fundamental sciences. Optomechanics, where photons are coupled to mechanical motion, provides the tools to control mechanical motion near the fundamental quantum limits. However even in cryogenic systems, massive (low frequency) mechanical resonators are in highly excited thermal states. Cooling them to, or close to, the motional ground state usually requires that the system is in the good cavity limit, i.e. the mechanical frequency greater than the photonic loss rate. Despite being in the bad cavity limit, we show a possible way to overcome this limitation by using a non-linear cavity. More specifically, we couple a magnetic cantilever to a microwave cavity, where an embedded SQUID makes the cavity magnetic field sensitive and also non-linear. We show, that the non-linearity has to be included in describing the back action and demonstrate a one order of magnitude improvement in the cooling. With our system it seems to be possible to overcome the back action limit, which limits the cooling performance in linear cavities. It could even be a way reach the ground state with a system in the bad cavity limit. |
Wednesday, March 17, 2021 3:24PM - 3:36PM Live |
P31.00003: Simulating quantum dynamical phenomena using classical oscillators Oleh Ivakhnenko, Sergey Shevchenko, Franco Nori Classical oscillators are ubiquitous in nature. With some modifications, they provide |
Wednesday, March 17, 2021 3:36PM - 3:48PM Live |
P31.00004: Many-body dynamics for the Dicke model based on the quantum measurement Yunjin Choi, Shan-Wen Tsai The Dicke model (DM) is a well-suited system for exploring enhanced metrology and quantum information processing. An entangled spin-boson cat-state in the DM is obtained when the spin and boson degrees of freedom interact in the strong coupling limit. This entangled spin-boson cat-state is a metrological resource to the spin cat-state in terms of the spin degrees of freedom. However, it is difficult to experimentally explore features of coherence of the entangled spin-boson cat state, and it is hard to control and measure the boson and spin degrees of freedom simultaneously. Treating the spin subsystem as the main system of interest, we consider the bosonic degrees of freedom as an environment that can be controlled and probed to some extent. We investigate a measurement process on the bosonic system to extract partial information about the spin system. |
Wednesday, March 17, 2021 3:48PM - 4:00PM Live |
P31.00005: Towards Quantum Optomechanics Using Bulk Acoustic Wave Resonators Hugo Doeleman, Tom Schatteburg, Maxwell Drimmer, Yiwen Chu Superconducting circuits are one of the most sophisticated architectures for quantum information processing to date. Their operation at microwave (MW) frequencies, however, confines these circuits to the base stages of dilution refrigerators. MW-to-optical conversion in the quantum regime could enhance the scalability and range of applications of superconducting circuits, using optical photons as noise-free carriers of quantum information that connect circuits in different refrigerators. This requires a conversion process that is coherent, efficient, and with minimal added noise, which has not been demonstrated yet. |
Wednesday, March 17, 2021 4:00PM - 4:12PM Live |
P31.00006: Switchable bipartite and genuine tripartite entanglement via an optoelectromechanical interface Cheng Jiang, Spyros Tserkis, Kevin Collins, Sho Onoe, Yong Li, Lin Tian Controllable multipartite entanglement is a crucial element in quantum information processing. Here we present a scheme that generates switchable bipartite and genuine tripartite entanglement between microwave and optical photons via an optoelectromechanical interface, where microwave and optical cavities are coupled to a mechanical mode with controllable coupling constants. We show that bipartite entanglement can be generated and switched between designated output photons by tuning an effective gauge phase between the coupling constants to the “sweet spots”. The bipartite entanglement, characterized by the entanglement of formation, is robust against the mechanical noise and the signal loss to the mechanical mode under the impedance-matching condition. When the gauge phase is tuned away from the “sweet spots,” genuine tripartite entanglement can be generated and verified with homodyne measurement on the quadratures of the output fields. Our result can lead to the implementation of controllable and robust multipartite entanglement in hybrid quantum systems operated in distinctively different frequencies. |
Wednesday, March 17, 2021 4:12PM - 4:24PM Live |
P31.00007: Controlling the charge dispersion of a nearly-open superconducting island Arno Bargerbos, Willemijn Uilhoorn, Marta Pita Vidal, Chung-Kai Yang, Peter Krogstrup, Leo Kouwenhoven, Gijs De Lange, Bernard Van Heck, Angela Kou We investigate the charge dispersion of a nanowire transmon hosting an accidental resonant level in the junction. We observe rapid suppression of the charge dispersion consistent with the scaling law resulting from diabatic transitions between Andreev bound states. We also observe improved qubit coherence times at the point of highest charge dispersion suppression. Our observations further our fundamental understanding of charging effects in superconductors and suggests novel approaches for building charge-insensitive qubits. Finally, we will discuss prospects for exploring the competition between superconductivity and Coulomb blockade by embedding a gate-defined quantum dot in the junction of the nanowire transmon. |
Wednesday, March 17, 2021 4:24PM - 4:36PM Live |
P31.00008: A reproducible design for multi-mode high-Q superconducting quantum electromechanics Amir Youssefi, Tatiana Vovk, Andrea Bancora, Tobias J. Kippenberg Superconducting electromechanical systems have been among the most successful platforms to study mechanical motion in the quantum regime. These systems are implemented by LC superconducting resonators with a mechanically-compliant capacitor. However, these systems suffer from the low reproducibility of the nanofabrication process, severely limiting their scalability. This restricts the realization of multi-mode electromechanical systems and limits the achievable mechanical quality factors, which largely determine the thermal coherence time. |
Wednesday, March 17, 2021 4:36PM - 4:48PM Live |
P31.00009: Dissipation-induced antiferromagnetic-like frustration in coupled photonic resonators Zejian Li, Ariane Soret, Cristiano Ciuti We show theoretically how to create dissipatively antiferromagnetic-like frustration between coupled photonic resonators with quantum nonlinearities [1]. The proposed reservoir-engineering scheme can be implemented in platforms such as circuit QED and generalized into arbitrary geometry, providing a fully controllable recipe for simulating antiferromagnetism and frustration in dissipative systems. |
Wednesday, March 17, 2021 4:48PM - 5:00PM Live |
P31.00010: Entanglement dynamics in dissipative photonic Mott insulators Kaelan Donatella, Alberto Biella, Alexandre Le Boité, Cristiano Ciuti We present a theoretical investigation of the entanglement dynamics in photonic Mott insulators in the presence of particle losses and dephasing [1], a class of quantum systems that has been recently demonstrated using superconducting quantum circuits [2]. We explore two configurations where entanglement is generated following the injection or extraction of a photon in the central site of a chain of microwave resonators. In spite of particle losses the quantum entanglement propagation exhibits a ballistic character with propagation speeds related to the different quasi-particles that are involved in the dynamics, namely photonic doublons and holons respectively. Our analysis reveals that photon dissipation has a strikingly asymmetric behavior in the two configurations with a much more dramatic role on the holon entanglement propagation than for doublons. |
Wednesday, March 17, 2021 5:00PM - 5:12PM Not Participating |
P31.00011: Repeated pumping of quantum systems Saikat Banerjee, Klaus G. Ziegler We consider a closed quantum system on a finite-dimensional Hilbert space. This system is repeatedly brought into contact with another closed system, from which it can either absorb energy or to which it can transfer energy. We study the dynamics of the full system and how this depends on various model parameters, e.g., on the strength of the coupling between the two systems and the time between the repeated contacts. For this purpose, we introduce a statistical approach to characterize the discrete-time statistics, which is determined by the contact between the two closed systems. This provides a sequence of probabilities for the time-evolved states of the system. In particular, we analyze the asymptotic probability (return probability) for a certain state of the system returning to itself. Moreover, we investigate the discrete-time correlation functions of the system to uncover a few salient topological features of the long-time dynamics. |
Wednesday, March 17, 2021 5:12PM - 5:24PM Live |
P31.00012: Long-lived Macroscopic Schrödinger Cat States in Atomic Ensembles Wei Qin, Adam Miranowicz, Hui Jing, Franco Nori How to create and stabilize large-size Schrödinger cat states remains challenging. This is mainly attributed to dissipation (and in particular, single-particle loss) induced by the environment. In Ref. [1], we proposed a method to obtain large-size and long-lived Schrödinger cat states in atomic ensembles. Specifically, we show that a fully quantum parametric amplifier can simultaneously lead to two-atomic-excitation loss and driving, and then robust atomic-cat states against spin dephasing. As a result, our approach enables an extremely long cat-state lifetime, which, under realistic parameters, is up to four orders of magnitude longer than that of common intracavity optical cat states, and reaches tens of milliseconds. Therefore, our work opens up a new way towards the long-standing goal of engineering large-size and long-lived cat states, with immediate interests both in fundamental studies of quantum mechanics and noise-immune quantum information processing. |
Wednesday, March 17, 2021 5:24PM - 5:36PM Live |
P31.00013: Optimal Strategies for Sending Atoms Around the Bend Doga Kurkcuoglu, Eddy M.E. Timmermans, Malcolm G Boshier In this presentation, I will discuss classical and quantum-based optimization schemes to minimize the transverse excitations of a guided cold atom matter wave after that wave has completed a bend, changing direction by a fixed bending angle $\theta_0$ over a pre-determined distance. The waveguide potential is constrained to two dimensions. We carry out the minimization with respect to the trajectory of the waveguide’s potential minimum. To determine the trajectory, we solve for the curvature function $\kappa(s)$ as a function of arc-length that minimizes the transverse excitation energy after the bend. The curved part of the waveguide is treated as a scattering perturbation in curvilinear coordinates. The waveguide that is defined by the minimal $\kappa(s)$-function causes transverse excitations with energy-values that that are orders of magnitude smaller than the transverse energy caused by transition bends with the standard circular or Euler's type (clothoid) curvatures. In the limit of a nearly plane-wave shapes incoming wave, the final transverse excitation energy after the bend can be chosen to vanish. |
Wednesday, March 17, 2021 5:36PM - 5:48PM Live |
P31.00014: Certification of high-dimensional entanglement in ultracold atom systems Niklas Euler Preparing strongly entangled quantum states with high confidence is a key requirement for the implementation of uprising quantum technologies, like quantum encryption protocols. To certify the entanglement available in any prepared state, reliable methods for its experimental detection are needed. One such method has been introduced recently and demonstrated with entangled photon pairs [J. Bavaresco, Nature Physics 2018], allowing one to extract the entanglement dimension, a measure for bipartite entanglement. In cold-atom systems, which represent the most advanced platform for quantum simulation, these methods cannot be applied directly due to limited readout capabilities. Here we present an adaptation of the scheme to ultracold atoms in optical lattices utilizing measurements in two experimentally accessible bases and study its robustness with respect to experimental imperfections and noise. We also extend the method to multipartite systems, enabling the certification of genuine tripartite entanglement. |
Wednesday, March 17, 2021 5:48PM - 6:00PM Live |
P31.00015: Impact of the Central Frequency of Environment on Non-Markovian Dynamics in PiezoelectricOptomechanical Devices Yusui Chen The piezoelectric optomechanical devices supply a promising experimental platform to realize the coherent and effective control and measurement on optical circuits working in Terahertz (THz) frequencies via superconducting electron devices typically working in Radio (MHz) frequencies. However, quantum fluctuations are unavoidable when the size of the mechanical oscillators enter the nanoscale. The consequences of the noisy environment are still challenging due to the lack of analytical tools. In this paper, a semi-classical and full-quantum model of piezoelectric optomechanical systems coupled to a noisy bosonic quantum environment is introduced and solved in terms of quantum-state diffusion (QSD) trajectories in the non-Markovianregime. We show that the noisy environment, particularly the central frequency of the environment, can enhance the entanglement generation between optical cavities and LC circuits in some parameter regimes. Moreover, we observe the critical points in the coefficient functions, which can lead the different behaviors in the system. Besides, we also witness the entanglement transfer between macroscopic objects due to the memory effect of the environment. |
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