Observation of Density-Dependent Gauge Fields in a Bose-Einstein Condensate Based on Micromotion Control in a Shaken Two-Dimensional Lattice

Abstract

We demonstrate a density-dependent gauge field, induced by atomic interactions, for quantum gases. The gauge field results from the synchronous coupling between the interactions and micromotion of the atoms in a modulated two-dimensional optical lattice. As a first step, we show that a coherent shaking of the lattice in two directions can couple the momentum and interactions of atoms and break the fourfold symmetry of the lattice. We then create a full interaction-induced gauge field by modulating the interaction strength in synchrony with the lattice shaking. When a condensate is loaded into this shaken lattice, the gauge field acts to preferentially prepare the system in different quasimomentum ground states depending on the modulation phase. We envision that these interaction-induced fields, created by fine control of micromotion, will provide a stepping stone to model new quantum phenomena within and beyond condensed matter physics.

Stability of matter-wave solitons in a density-dependent gauge theory

“…The condensate dynamics in these models can be greatly modified, including collective modes which violate Kohn's theorem [56][57][58][59], unconventional vortex dynamics [60,61], and the emergence of chiral solitons which feature non-integrable collision dynamics [62]. Very recently, experiments have appeared in which a dynamical gauge theory was realised in trapped ion systems [63] and a density-dependent synthetic gauge field in a Bose-Einstein condensate loaded into a two-dimensional lattice [64].…”

Asymmetric Particle Transport and Light-Cone Dynamics Induced by Anyonic Statistics

“…Anyons in 1D exhibit a number of intriguing properties, including statistics-induced quantum phase transitions [37][38][39][40], asymmetric momentum distribution in ground states [32][33][34][35][36][37]41], continuous fermionization of bosonic atoms [42], and anyonic symmetry protected topological phases [41]. Several schemes have been proposed for implementing anyonic statistics in ultracold atoms [37,38,[41][42][43] and photonic systems [44] by engineering occupation-number dependent hopping using Raman-assisted tunneling [37,38] or periodic driving [42,44]. Cold atom quantum systems [45][46][47] are powerful platforms not only for probing equilibrium properties of many-body systems, but also for studying uncharted non-equilibrium physics [48][49][50][51][52][53][54][55][56][57].…”

“…In contrast to previous studies on ground-state properties [30, 33-35, 37, 38, 41, 42] or hard-core cases [29,36,60] of 1D anyons, here we focus on the out-of-equilibrium physics of anyonic systems which can be implemented in experiment [37,38,[41][42][43]. Moreover, we focus mainly on observables that both reveal anyonic properties directly and can be probed in cold atom systems, where the anyonic statistics can be realized via correlated-tunneling terms [42].…”

“…Crucially, our work provides a new method for detecting anyonic statistics even in systems where the ground state is difficult to prepare. interactions-the anyon-Hubbard model [37,38,[41][42][43][44]:…”

Towards analog quantum simulations of lattice gauge theories with trapped ions

“…Simple low-dimensional field theories such as relativistic Dirac fermions, 1+1D 1 and 2+1D scalar and fermionic quantum electrodynamics (QED), and non-Abelian SU (2) and SO(3) gauge theories have been studied in this context, and proposals exist to map the desired lattice Hamiltonians (or their approximated forms) to that of the engineered Hamiltonian of neutral atoms in optical lattices . Recent implementations of simple static and dynamical gauge theories with neutral atoms in optical lattices [42][43][44][45][46][47], however, demonstrate the challenge of simulating more phenomenologically-relevant gauge theories. Given the current size of controlled quantum systems, only a small number of degrees of freedom can be studied, leading to unavoidable truncations in the Hilbert space of a gauge theory that lives in a continuous infinite-volume spacetime.…”