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| Main Authors: | , , , , |
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| Format: | Preprint |
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2024
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| Online Access: | https://arxiv.org/abs/2401.01310 |
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| _version_ | 1866911862203875328 |
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| author | Gangwar, Sanu Kumar Ravisankar, Rajamanickam Fabrelli, Henrique Muruganandam, Paulsamy Mishra, Pankaj Kumar |
| author_facet | Gangwar, Sanu Kumar Ravisankar, Rajamanickam Fabrelli, Henrique Muruganandam, Paulsamy Mishra, Pankaj Kumar |
| contents | We present the analytical and numerical results on the collective excitation spectrum of quasi-one-dimensional spin-orbit (SO) coupled spin-1 Bose-Einstein condensates. The collective excitation spectrum, using Bogoliubov-de-Gennes theory, reveals the existence of a diverse range of phases in the SO and Rabi ($k_L-Ω$) coupling plane. Based on eigenvalue of the excitation spectrum, we categorize the $k_L-Ω$ plane into three distinct regions. In region I, a stable mode with phonon-like excitations is observed. In region IIa, single and multi-band instabilities are noted with a gapped mode, while multi-band instability accompanied by a gapless mode between low-lying and first excited states is realized in region IIb, which also provides evidence of unstable avoided crossing between low-lying and first excited modes The gap between low-lying and first-excited states increases upon increasing the Rabi coupling while decreases upon increase of SO coupling. Using eigenvector analysis, we confirm the presence of the spin-dipole mode in the spin-like modes in Region II. We corroborate the nature of the collective excitation through real-time dynamical evolution of the ground state perturbed with the quench of the trap using the mean-field Gross-Pitaevskii model. This analysis suggests the presence of dynamical instability leading to the disappearance of the $0$-th component of the condensate. In Region III, mainly encompassing $Ω\sim 0$ and finite $k_L$, we observe phonon-like excitations in both the first excited and the low-lying state. The eigenvectors in this region reveal alternative in- and out-of-phase behaviours of the spin components. Numerical analysis reveals the presence of a super stripe phase for small Rabi coupling in this region, wherein the eigenvector indicates the presence of more complicated spin-like-density mixed modes. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_01310 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Emergence of unstable avoided crossing in the collective excitations of spin-1 spin-orbit coupled Bose-Einstein condensates Gangwar, Sanu Kumar Ravisankar, Rajamanickam Fabrelli, Henrique Muruganandam, Paulsamy Mishra, Pankaj Kumar Quantum Gases We present the analytical and numerical results on the collective excitation spectrum of quasi-one-dimensional spin-orbit (SO) coupled spin-1 Bose-Einstein condensates. The collective excitation spectrum, using Bogoliubov-de-Gennes theory, reveals the existence of a diverse range of phases in the SO and Rabi ($k_L-Ω$) coupling plane. Based on eigenvalue of the excitation spectrum, we categorize the $k_L-Ω$ plane into three distinct regions. In region I, a stable mode with phonon-like excitations is observed. In region IIa, single and multi-band instabilities are noted with a gapped mode, while multi-band instability accompanied by a gapless mode between low-lying and first excited states is realized in region IIb, which also provides evidence of unstable avoided crossing between low-lying and first excited modes The gap between low-lying and first-excited states increases upon increasing the Rabi coupling while decreases upon increase of SO coupling. Using eigenvector analysis, we confirm the presence of the spin-dipole mode in the spin-like modes in Region II. We corroborate the nature of the collective excitation through real-time dynamical evolution of the ground state perturbed with the quench of the trap using the mean-field Gross-Pitaevskii model. This analysis suggests the presence of dynamical instability leading to the disappearance of the $0$-th component of the condensate. In Region III, mainly encompassing $Ω\sim 0$ and finite $k_L$, we observe phonon-like excitations in both the first excited and the low-lying state. The eigenvectors in this region reveal alternative in- and out-of-phase behaviours of the spin components. Numerical analysis reveals the presence of a super stripe phase for small Rabi coupling in this region, wherein the eigenvector indicates the presence of more complicated spin-like-density mixed modes. |
| title | Emergence of unstable avoided crossing in the collective excitations of spin-1 spin-orbit coupled Bose-Einstein condensates |
| topic | Quantum Gases |
| url | https://arxiv.org/abs/2401.01310 |