Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit coupling
Parity-time ( $\mathcal{PT}$ ) symmetry has drawn great research interest in non-Hermitian physics. Recently, there is an emerging model of $\mathcal{PT}$ -symmetric spin–orbit coupling (SOC) which could be realized with spin-1/2 atomic Bose–Einstein condensates (BECs) when the two spin components a...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | New Journal of Physics |
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| Online Access: | https://doi.org/10.1088/1367-2630/ad1417 |
| _version_ | 1827395887826993152 |
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| author | Jieli Qin Lu Zhou Guangjiong Dong |
| author_facet | Jieli Qin Lu Zhou Guangjiong Dong |
| author_sort | Jieli Qin |
| collection | DOAJ |
| description | Parity-time ( $\mathcal{PT}$ ) symmetry has drawn great research interest in non-Hermitian physics. Recently, there is an emerging model of $\mathcal{PT}$ -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 $\mathcal{PT}$ -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 $\mathcal{PT}$ -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. |
| first_indexed | 2024-03-08T18:42:26Z |
| format | Article |
| id | doaj.art-e8d5f81ee702420d8a66b2836d264881 |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-08T18:42:26Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-e8d5f81ee702420d8a66b2836d2648812023-12-29T06:20:24ZengIOP PublishingNew Journal of Physics1367-26302023-01-01251212305310.1088/1367-2630/ad1417Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit couplingJieli Qin0https://orcid.org/0000-0003-4112-2875Lu Zhou1Guangjiong Dong2School of Physics and Materials Science, Guangzhou University, Guangzhou Higher Education Mega Center, 230 Wai Huan Xi Road, Guangzhou 510006, People’s Republic of ChinaDepartment of Physics, School of Physics and Electronic Science, East China Normal University , Shanghai 200241, People’s Republic of China; Collaborative Innovation Center of Extreme Optics, Shanxi University , Taiyuan, Shanxi 030006, People’s Republic of ChinaState Key Laboratory of Precision Spectroscopy, East China Normal University , Shanghai 200241, People’s Republic of China; Collaborative Innovation Center of Extreme Optics, Shanxi University , Taiyuan, Shanxi 030006, People’s Republic of ChinaParity-time ( $\mathcal{PT}$ ) symmetry has drawn great research interest in non-Hermitian physics. Recently, there is an emerging model of $\mathcal{PT}$ -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 $\mathcal{PT}$ -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 $\mathcal{PT}$ -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.https://doi.org/10.1088/1367-2630/ad1417parity-time symmetrycollective excitationmodulation instabilityBose–Einstein condensatespin–orbit coupling |
| spellingShingle | Jieli Qin Lu Zhou Guangjiong Dong Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit coupling New Journal of Physics parity-time symmetry collective excitation modulation instability Bose–Einstein condensate spin–orbit coupling |
| title | Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit coupling |
| title_full | Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit coupling |
| title_fullStr | Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit coupling |
| title_full_unstemmed | Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit coupling |
| title_short | Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit coupling |
| title_sort | phonon and maxon instability in bose einstein condensates with parity time symmetric spin orbit coupling |
| topic | parity-time symmetry collective excitation modulation instability Bose–Einstein condensate spin–orbit coupling |
| url | https://doi.org/10.1088/1367-2630/ad1417 |
| work_keys_str_mv | AT jieliqin phononandmaxoninstabilityinboseeinsteincondensateswithparitytimesymmetricspinorbitcoupling AT luzhou phononandmaxoninstabilityinboseeinsteincondensateswithparitytimesymmetricspinorbitcoupling AT guangjiongdong phononandmaxoninstabilityinboseeinsteincondensateswithparitytimesymmetricspinorbitcoupling |