We report an experimental study of quench dynamics across the superfluid transition temperature ${T}_{\mathrm{c}}$ in a strongly interacting Fermi gas by ramping down the trapping potential. The nonzero quasicondensate number ${N}_{0}$ at temperatures significantly above ${T}_{\mathrm{c}}$ in the unitary and the BEC regimes is consistent with the pseudogap physics via preformed pairs. Below ${T}_{\mathrm{c}}$ , a rapid growth of ${N}_{0}$ is accompanied by the spontaneous generation of tens of vortices. We observe a power-law scaling of the vortex density versus the quasicondensate formation time, consistent with the Kibble-Zurek theory. Our work provides an example of studying emerged many-body physics by quench dynamics and paves the way for studying the quantum turbulence in a strongly interacting Fermi gas.We report an experimental study of quench dynamics across the superfluid transition temperature ${T}_{\mathrm{c}}$ in a strongly interacting Fermi gas by ramping down the trapping potential. The nonzero quasicondensate number ${N}_{0}$ at temperatures significantly above ${T}_{\mathrm{c}}$ in the unitary and the BEC regimes is consistent with the pseudogap physics via preformed pairs. Below ${T}_{\mathrm{c}}$, a rapid growth of ${N}_{0}$ is accompanied by the spontaneous generation of tens of vortices. We observe a power-law scaling of the vortex density versus the quasicondensate formation time, consistent with the Kibble-Zurek theory. Our work provides an example of studying emerged many-body physics by quench dynamics and paves the way for studying the quantum turbulence in a strongly interacting Fermi gas.

arXiv:1902.07558Physical Review ResearchNov 15, 202113 citations

Quantum Phase Transition in the BCS-to-BEC Evolution of p-wave Fermi Gases

S. S. Botelho, C. A. R. Sá de Melo

arXiv:cond-mat/0504263Journal of Low Temperature PhysicsSep 1, 200586 citations

Topological phase transition in the quench dynamics of a one-dimensional Fermi gas with spin–orbit coupling

Pei Wang, Wei Yi, Gao Xianlong

We study the quench dynamics of a one-dimensional ultracold Fermi gas with synthetic spin-orbit coupling. At equilibrium, the ground state of the system can undergo a topological phase transition and become a topological superfluid with Majorana edge states. As the interaction is quenched near the topological phase boundary, we identify an interesting dynamical phase transition of the quenched state in the long-time limit, characterized by an abrupt change of the pairing gap at a critical quenched interaction strength. We further demonstrate the topological nature of this dynamical phase transition from edge-state analysis of the quenched states. Our findings provide interesting clues for the understanding of topological phase transitions in dynamical processes, and can be useful for the dynamical detection of Majorana edge states in corresponding systems.We study the quench dynamics of a one-dimensional ultracold Fermi gas with synthetic spin-orbit coupling. At equilibrium, the ground state of the system can undergo a topological phase transition and become a topological superfluid with Majorana edge states. As the interaction is quenched near the topological phase boundary, we identify an interesting dynamical phase transition of the quenched state in the long-time limit, characterized by an abrupt change of the pairing gap at a critical quenched interaction strength. We further demonstrate the topological nature of this dynamical phase transition from edge-state analysis of the quenched states. Our findings provide interesting clues for the understanding of topological phase transitions in dynamical processes, and can be useful for the dynamical detection of Majorana edge states in corresponding systems.

arXiv:1404.6848New Journal of PhysicsJan 15, 201511 citations

Quantum Quench Dynamics of a Fermi Impurity

Marko Cetina, Michael Jag, Rianne S. Lous +6 more

Bulletin of the American Physical SocietyJun 9, 20150 citations

Universal scaling of the dynamic BKT transition in quenched 2D Bose gases

Shinichi Sunami, Vijay Pal Singh, David Garrick +6 more

The understanding of nonequilibrium dynamics in many-body quantum systems is a fundamental issue in statistical physics. Experiments that probe universal properties of these systems can address such foundational questions. In this study, we report the measurement of universal dynamics triggered by a quench from the superfluid to normal phase across the Berezinskii-Kosterlitz-Thouless transition in a two-dimensional (2D) Bose gas. We reduced the density by splitting the 2D gas in two, realizing a quench across the critical point. The subsequent relaxation dynamics were probed with matter-wave interferometry to measure the local phase fluctuations. We show that the time evolution of both the phase correlation function and vortex density obeys universal scaling laws. This conclusion is supported by classical-field simulations and interpreted by means of real-time renormalization group theory.The understanding of nonequilibrium dynamics in many-body quantum systems is a fundamental issue in statistical physics. Experiments that probe universal properties of these systems can address such foundational questions. In this study, we report the measurement of universal dynamics triggered by a quench from the superfluid to normal phase across the Berezinskii-Kosterlitz-Thouless transition in a two-dimensional (2D) Bose gas. We reduced the density by splitting the 2D gas in two, realizing a quench across the critical point. The subsequent relaxation dynamics were probed with matter-wave interferometry to measure the local phase fluctuations. We show that the time evolution of both the phase correlation function and vortex density obeys universal scaling laws. This conclusion is supported by classical-field simulations and interpreted by means of real-time renormalization group theory.

arXiv:2209.13587ScienceOct 26, 202330 citations

We report an experimental study of quench dynamics across the superfluid transition temperature

{T}_{\mathrm{c}}

in a strongly interacting Fermi gas by ramping down the trapping potential. The nonzero quasicondensate number

{N}_{0}

at temperatures significantly above

{T}_{\mathrm{c}}

in the unitary and the BEC regimes is consistent with the pseudogap physics via preformed pairs. Below

{T}_{\mathrm{c}}

, a rapid growth of

{N}_{0}

is accompanied by the spontaneous generation of tens of vortices. We observe a power-law scaling of the vortex density versus the quasicondensate formation time, consistent with the Kibble-Zurek theory. Our work provides an example of studying emerged many-body physics by quench dynamics and paves the way for studying the quantum turbulence in a strongly interacting Fermi gas.