Engineering tunable local loss in a synthetic lattice of momentum states

Abstract

Dissipation can serve as a powerful resource for controlling the behavior of open quantum systems.Recently there has been a surge of interest in the influence of dissipative coupling on large quantum systems and, more specifically, how these processes can influence band topology and phenomena like many-body localization. Here, we explore the engineering of local, tunable dissipation in so-called synthetic lattices, arrays of quantum states that are parametrically coupled in a fashion analogous to quantum tunneling. Considering the specific case of momentum-state lattices, we investigate two distinct mechanisms for engineering controlled loss: one relying on an explicit form of dissipation by spontaneous emission, and another relying on reversible coupling to a large reservoir of unoccupied states. We experimentally implement the latter and demonstrate the ability to tune the local loss coefficient over a large range. The introduction of controlled loss to the synthetic lattice toolbox promises to pave the way for studying the interplay of dissipation with topology, disorder, and interactions.

Ultracold quantum wires with localized losses: Many-body quantum Zeno effect

“…Recently, experiments with ultracold atoms have directly observed the QZE in many-body systems [10][11][12] . In particular, its observation was recently reported for a Bose gas in a quasi onedimensional optical lattice, subject to a localized dissipation 12,13 , which was accompanied by a number of theoretical works [14][15][16][17][18][19][20][21][22][23][24][25][26][27] . More recently, experiments with ultracold fermionic wires in the presence of localized dissipation were performed 28,29 , studying the interplay between localized losses and transport.…”

Enhanced Fermion Pairing and Superfluidity by an Imaginary Magnetic Field

“…In this work, we report another efficient tool for generating strong pairing superfluid, namely, an imaginary magnetic field (IMF). Experimentally, the IMF can be realized in non-Hermitian atomic systems by laser-assisted spin-selective dissipations (Li et al., 2019, Lapp et al., 2018). Consider the spin-1/2(↑,↓) system; the IMF can be equivalently achieved by applying a laser field uniquely to spin-↓ atom, which is resonantly coupled to a highly excited atomic state and causes loss.…”

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

“…Any population of the reservoir (sites with n < −1) is therefore considered as loss during this period. It follows from the second-order perturbation that the effective on-site loss rate for | − 1 at short times is γ ≈ t 2 c /t r [45]. For larger t c , γ should deviate from t 2 c /t r .…”