Emergent $\mathcal{PT}$-symmetry breaking of collective modes with topological critical phenomena
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arXiv
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| Hauptverfasser: | , , |
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| Format: | Preprint |
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2021
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| _version_ | 1866912780670468096 |
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| author | Pan, Jian-Song Yi, Wei Gong, Jiangbin |
| author_facet | Pan, Jian-Song Yi, Wei Gong, Jiangbin |
| contents | The spontaneous breaking of parity-time ($\mathcal{PT}$) symmetry yields rich critical behavior in non-Hermitian systems, and has stimulated much interest, albeit most previous studies were performed within the single-particle or mean-field framework. Here, by studying the collective excitations of a Fermi superfluid with $\mathcal{PT}$-symmetric spin-orbit coupling, we uncover an emergent $\mathcal{PT}$-symmetry breaking in the Anderson-Bogoliubov (AB) collective modes, even as the superfluid ground state retains an unbroken $\mathcal{PT}$ symmetry. {The critical point of the transition is marked by a non-analytic kink in the speed of sound, which derives from the coalescence and annihilation of the AB mode and its hole partner, reminiscent of the particle-antiparticle annihilation. The system consequently becomes immune to low-frequency external perturbations at the critical point, a phenomenon associated with the spectral topology of the complex quasiparticle dispersion. This critical phenomenon offers a fascinating route toward perturbation-free quantum states. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2103_00450 |
| institution | arXiv |
| publishDate | 2021 |
| record_format | arxiv |
| spellingShingle | Emergent $\mathcal{PT}$-symmetry breaking of collective modes with topological critical phenomena Pan, Jian-Song Yi, Wei Gong, Jiangbin Quantum Gases Mesoscale and Nanoscale Physics Superconductivity Quantum Physics The spontaneous breaking of parity-time ($\mathcal{PT}$) symmetry yields rich critical behavior in non-Hermitian systems, and has stimulated much interest, albeit most previous studies were performed within the single-particle or mean-field framework. Here, by studying the collective excitations of a Fermi superfluid with $\mathcal{PT}$-symmetric spin-orbit coupling, we uncover an emergent $\mathcal{PT}$-symmetry breaking in the Anderson-Bogoliubov (AB) collective modes, even as the superfluid ground state retains an unbroken $\mathcal{PT}$ symmetry. {The critical point of the transition is marked by a non-analytic kink in the speed of sound, which derives from the coalescence and annihilation of the AB mode and its hole partner, reminiscent of the particle-antiparticle annihilation. The system consequently becomes immune to low-frequency external perturbations at the critical point, a phenomenon associated with the spectral topology of the complex quasiparticle dispersion. This critical phenomenon offers a fascinating route toward perturbation-free quantum states. |
| title | Emergent $\mathcal{PT}$-symmetry breaking of collective modes with topological critical phenomena |
| topic | Quantum Gases Mesoscale and Nanoscale Physics Superconductivity Quantum Physics |
| url | https://arxiv.org/abs/2103.00450 |