Tunable Nonreciprocal Quantum Transport through a Dissipative Aharonov-Bohm Ring in Ultracold Atoms

Wei Gou, Tao Chen, Dizhou Xie, Teng Xiao, Tian-Shu Deng, Bryce Gadway, Wei Yi, and Bo Yan

Phys. Rev. Lett. 124, 070402 – Published 20 February 2020

Abstract

We report the experimental observation of tunable, nonreciprocal quantum transport of a Bose-Einstein condensate in a momentum lattice. By implementing a dissipative Aharonov-Bohm (AB) ring in momentum space and sending atoms through it, we demonstrate a directional atom flow by measuring the momentum distribution of the condensate at different times. While the dissipative AB ring is characterized by the synthetic magnetic flux through the ring and the laser-induced loss on it, both the propagation direction and transport rate of the atom flow sensitively depend on these highly tunable parameters. We demonstrate that the nonreciprocity originates from the interplay of the synthetic magnetic flux and the laser-induced loss, which simultaneously breaks the inversion and the time-reversal symmetries. Our results open up the avenue for investigating nonreciprocal dynamics in cold atoms, and highlight the dissipative AB ring as a flexible building element for applications in quantum simulation and quantum information.

Received 3 November 2019
Accepted 3 February 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.070402

Physics Subject Headings (PhySH)

Bose-Einstein condensates Quantum control Quantum simulation Quantum transport

Quantum Information, Science & TechnologyAtomic, Molecular & Optical

Authors & Affiliations

Wei Gou ^1,‡, Tao Chen ^1,‡, Dizhou Xie¹, Teng Xiao ¹, Tian-Shu Deng², Bryce Gadway³, Wei Yi^4,5,*, and Bo Yan ^1,6,7,†

¹Interdisciplinary Center of Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device of Physics Department, Zhejiang University, Hangzhou 310027, China
²Institute for Advanced Study, Tsinghua University, Beijing, 100084, China
³Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
⁴CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
⁵CAS Center For Excellence in Quantum Information and Quantum Physics, Hefei 230026, China
⁶Collaborative Innovation Centre of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
⁷Key Laboratory of Quantum Optics, Chinese Academy of Sciences, Shanghai, 200800, China

^*wyiz@ustc.edu.cn
^†yanbohang@zju.edu.cn
^‡These authors contributed equally to this work.

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 124, Iss. 7 — 21 February 2020

Reuse & Permissions

Access Options

Article Available via CHORUS

Download Accepted Manuscript

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
(a) Schematic illustration of a dissipative AB ring (the 3-site triangle within the dashed box) along a lattice. The green, gray, and orange bonds correspond to hopping rates $t$ , $t e^{- i ϕ / 2}$ , and $t^{'}$ , respectively, between adjacent sites. The vertex of the ring (site 0 in orange) features an on-site loss with rate $γ$ . (b) Numerical simulation of nonreciprocal atom transport through the AB ring in (a), where we initialize atoms on the lattice sites $\pm 50$ to the left or right of the ring, and plot the time-dependent population distribution [40]. We fix $γ / t = 1$ and $ϕ = 3 π / 2$ for the calculation, in which case atoms incoming from the left are lost to the reservoir through site 0, whereas atoms incoming from the right can transport through. (c) Illustration of the experimental implementation of the momentum lattice and the AB ring. The momentum lattice is formed with multiple pairs of two-photon Bragg transitions (solid arrows), while momentum states $| n = 1 ⟩$ are coupled to $| n = - 1 ⟩$ with a four-photon second-order Bragg process (dashed arrows). Here the frequency components $ω_{n}$ of the left-going Bragg laser satisfies $ω_{n} = ω_{+} - 4 (2 n + 1) E_{r} / ℏ$ , while $ω_{-} = ω_{+}$ . (d) Implementation of on-site loss and the mapping of the system to (a). The left side of the lattice with $n < - 1$ is mapped to a reservoir, with hopping rate $t_{r}$ within the reservoir and $t_{c}$ between the system and the reservoir. The laser-induced hopping rate between momentum states $| - 1 ⟩$ and $| 1 ⟩$ is $t^{'}$ , which allows us to map $| - 1 ⟩$ to lattice site 0 in (a) with an effective loss rate $γ \approx t_{c}^{2} / t_{r}$ .
Reuse & Permissions
Figure 2
(a),(b) Phase-dependent transport for (a) $ϕ = π / 2$ and (b) $ϕ = 3 π / 2$ . From left to right, the panels are experimental data, numerical simulation using the full Hamiltonian, and simulation using the effective Hamiltonian [40]. The masked regions correspond to the reservoir. (c) The population loss $P_{ℓ}$ as a function of $ϕ$ , after an evolution time of $3 ℏ / t$ . Experimental data are shown as purple dots with error bars. The dashed line is from the numerical simulation with the full Hamiltonian, and the solid line is the prediction from the effective Hamiltonian (1). For all cases, we fix the effective loss rate $γ / t = 1$ , and initialize the BEC on site $| 0 ⟩$ .
Reuse & Permissions
Figure 3
Dependence of the population loss $P_{ℓ}$ on the effective loss rate $γ$ . Two datasets are shown, with the synthetic magnetic flux $ϕ = π / 2$ (green circles) and $3 π / 2$ (purple squares), respectively. We also show results from numerical simulations using the effective (solid lines) and the full Hamiltonians (dashed lines). For all cases, the evolution time is taken to be $τ = 3 ℏ / t$ .
Reuse & Permissions
Figure 4
Schematic illustration of a lattice with coupled dissipative AB rings.
Reuse & Permissions

Physical Review Letters