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MON: Monday Contributed Sessions

MON 3: Many-Body Quantum Dynamics I

MON 3.8: Talk

Monday, September 8, 2025, 16:00–16:15, ZHG003

Josephson-like dynamics of the low-energy crystal Goldstone mode in trapped supersolid spin-orbit-coupled Bose gases — •Kevin T. Geier, Vijay Pal Singh, Juan Polo, and Luigi Amico — Quantum Research Center, Technology Innovation Institute, PO Box 9639, Abu Dhabi, United Arab Emirates

Supersolidity is a phase of quantum matter that combines superfluidity with a solid-like crystal structure. These exotic properties are characterized by the spontaneous breaking of both phase and translational symmetry. According to Goldstone's theorem, there is a gapless mode associated with each broken symmetry. For the broken translational invariance, the Goldstone mode corresponds to a rigid translation of the supersolid pattern, which costs zero energy in an infinite system. However, in a finite system, e.g., in the presence of an external trapping potential, this motion acquires a finite energy cost and can exhibit nontrivial dynamics. Here, we show that the low-energy crystal Goldstone mode in trapped supersolid spin-orbit-coupled Bose-Einstein condensates can exhibit Josephson-like dynamics, analogous to a nonrigid pendulum. Depending on the amount of energy injected into the system by a uniform spin perturbation, the supersolid density stripes either oscillate back and forth, or undergo a unidirectional motion. We illustrate this dynamics through numerical simulations and explain the different regimes analytically under a two-mode approximation, where the equations of motion have the same structure as those governing a bosonic Josephson junction. Finally, we discuss perspectives for an observation of these effects in cold-atom experiments.

Keywords: Supersolidity; Goldstone modes; Bose-Einstein condensates; Spin-orbit coupling; Josephson effect