Observation of Momentum Space Josephson Effects

Abstract

The momentum space Josephson effect describes the supercurrent flow between weakly coupled Bose-Einstein condensates (BECs) at two discrete momentum states. Here, we experimentally observe this exotic phenomenon using a BEC with Raman-induced spin-orbit coupling, where the tunneling between two local band minima is implemented by the momentum kick of an additional optical lattice. A sudden quench of the Raman detuning induces coherent spin-momentum oscillations of the BEC, which is analogous to the a.c. Josephson effect. We observe both plasma and regular Josephson oscillations in different parameter regimes. The experimental results agree well with the theoretical model and numerical simulation, and showcase the important role of nonlinear interactions. We also show that the measurement of the Josephson plasma frequency gives the Bogoliubov zero quasimomentum gap, which determines the mass of the corresponding pseudo-Goldstone mode, a long-sought phenomenon in particle physics. The observation of momentum space Josephson physics offers an exciting platform for quantum simulation and sensing utilizing momentum states as a synthetic degree.

12 pages, 11 figures

References in corpus (12)

• Spin-Orbit Coupled Spinor Bose-Einstein Condensates
• Tunable Spin-Orbit Coupling via Strong Driving in Ultracold Atom Systems
• Measurement of collective excitations in a spin-orbit-coupled Bose-Einstein condensate
• Connecting dissipation and phase slips in a Josephson junction between fermionic superfluids
• Correlated dynamics in a synthetic lattice of momentum states
• Temperature square dependence of the low frequency 1/f charge noise in the Josephson junction qubits
• Nonlinear dynamics in a synthetic momentum state lattice
• Josephson plasma oscillations and the Gross-Pitaevskii equation: Bogoliubov approach vs two-mode model
• Quantum whistling in superfluid 4He
• Field theoretic description of the abelian and non-abelian Josephson effect
• Pseudo-Goldstone Excitations in a Striped Bose-Einstein Condensate
• Spin-asymmetric Josephson plasma oscillations

Cited by in corpus (8)

• Self-Adapted Josephson Oscillation of Dark-Bright Solitons under Constant Forces
• Quantum action of the Josephson dynamics
• Band-edge superfluid of Bose-Einstein condensates in the spin-orbit-coupled Zeeman lattice
• Dissipation Driven Coherent Dynamics Observed in Bose-Einstein Condensates
• Violation of the Leggett-Garg inequality for dynamics of a Bose-Einstein condensate in a double-well potential
• Tailoring Synthetic Gauge Fields in Ultracold Atoms via Spatially Engineered Vector Beams
• Collective modes of two-species Bose-Einstein condensates in a Josephson junction barrier
• Bi-Josephson Effect in a Driven-Dissipative Supersolid