Instabilities of a Bose-Einstein condensate with mixed nonlinear and linear lattices

Jiang, Hong; Wang, Chenhui; Zhang, Yongping

doi:10.1103/physreve.107.044219

Cited by 3 publications

(1 citation statement)

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“…Besides the dynamical instability, the energetic instability is another instability mechanism that is widely considered in nonlinear physics [71][72][73]. It states that if the eigen values of diag{1, 1, −1, −1} • H BdG are negative, the perturbations will lower the ground state energy, and the system is energetically unstable.…”

Section: Bdg Equation For the Collective Excitationmentioning

confidence: 99%

Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit coupling

Qin,

Zhou,

Dong

2023

New J. Phys.

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Parity-time ( P T ) symmetry has drawn great research interest in non-Hermitian physics. Recently, there is an emerging model of P T -symmetric spin–orbit coupling (SOC) which could be realized with spin-1/2 atomic Bose–Einstein condensates (BECs) when the two spin components are respectively subjected to momentum-dependent gain and loss (Qin et al 2022 New J. Phys. 24 063025). In this model, inter-atom interaction has no influence on the P T -symmetric plane waves. Thus, collective excitation playing the role of fingerprint of inter-atom interaction is investigated in this paper. For the phonon excitation, it is shown that the repulsive interaction between atoms in different spin states, which tends to drive the atoms to populate in only one spin component, can break the P T -symmetry, and leads to a phonon instability. Whereas, for the case of the phonon-maxon-roton collective excitation spectrum, the repulsive interaction between atoms in different spin states can lead to a maxon instability, which does not occur in Hermitian BEC systems (dipolar BECs or BECs with Raman induced SOC). Simulation of the time evolution of the plane wave solution against small noise shows that the maxon instability can result in the formation of a supersolid-like stripe pattern at the initial stage, but the non-Hermitian nature of the system finally destroys the pattern. The phase diagram of stability shows that the Rabi coupling and repulsive interaction between the atoms in the same spin state can stabilize the system.

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Section: Bdg Equation For the Collective Excitationmentioning

confidence: 99%