Yamamoto Kazuki, Nakagawa Masaya, Tsuji Naoto, Ueda Masahito, Kawakami Norio
Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
Department of Physics, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan.
Phys Rev Lett. 2021 Jul 30;127(5):055301. doi: 10.1103/PhysRevLett.127.055301.
We predict a new mechanism to induce collective excitations and a nonequilibrium phase transition of fermionic superfluids via a sudden switch on of two-body loss, for which we extend the BCS theory to fully incorporate a change in particle number. We find that a sudden switch on of dissipation induces an amplitude oscillation of the superfluid order parameter accompanied by a chirped phase rotation as a consequence of particle loss. We demonstrate that when dissipation is introduced to one of the two superfluids coupled via a Josephson junction, it gives rise to a nonequilibrium dynamical phase transition characterized by the vanishing dc Josephson current. The dissipation-induced collective modes and nonequilibrium phase transition can be realized with ultracold fermionic atoms subject to inelastic collisions.
我们预测了一种通过突然开启两体损耗来诱导费米子超流体集体激发和非平衡相变的新机制，为此我们扩展了BCS理论以充分纳入粒子数的变化。我们发现，由于粒子损失，突然开启的耗散会诱导超流序参量的幅度振荡，并伴随着啁啾相位旋转。我们证明，当通过约瑟夫森结耦合的两个超流体之一引入耗散时，会导致以直流约瑟夫森电流消失为特征的非平衡动力学相变。耗散诱导的集体模式和非平衡相变可以用经历非弹性碰撞的超冷费米子原子来实现。
