Chiacchio Ezequiel I Rodríguez, Nunnenkamp Andreas, Brunelli Matteo
Entropica Labs, 186B Telok Ayer Street 068632, Singapore, Singapore.
Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria.
Phys Rev Lett. 2023 Sep 15;131(11):113602. doi: 10.1103/PhysRevLett.131.113602.
We investigate the physics of an open two-component Dicke model, where the light field mediates nonreciprocal interactions between two spin species. We show that the model, which we dub nonreciprocal Dicke model, exhibits a discrete parity-time (PT) symmetry and we characterize the emergence of a nonstationary phase, so far explained in terms of dissipation-induced instability, as spontaneous breaking of PT symmetry. We further show that such PT symmetry breaking embodies an instance of a nonreciprocal phase transition, a concept recently introduced by Fruchart et al. [Nature (London) 592, 363 (2021)NATUAS0028-083610.1038/s41586-021-03375-9]. Remarkably, the phase transition in our model does not necessitate the presence of any underlying broken symmetry or exceptional points in the spectrum, both believed to be essential requirements for nonreciprocal phase transitions. Our results establish driven-dissipative light-matter systems as a new avenue for exploring nonreciprocal phase transitions and contribute to the theory of nonreciprocal collective phenomena.
我们研究了一个开放的双组分狄克模型的物理性质，其中光场介导了两种自旋粒子之间的非互易相互作用。我们表明，我们称之为非互易狄克模型的该模型展现出离散的宇称-时间（PT）对称性，并且我们将一种非定常相的出现描述为PT对称性的自发破缺，这种非定常相迄今为止是根据耗散诱导的不稳定性来解释的。我们进一步表明，这种PT对称性破缺体现了一种非互易相变的情况，这是弗鲁沙尔等人最近提出的一个概念[《自然》（伦敦）592, 363 (2021)NATUAS0028 - 083610.1038/s41586 - 021 - 03375 - 9]。值得注意的是，我们模型中的相变并不需要光谱中存在任何潜在的破缺对称性或例外点，而这两者都被认为是非互易相变的基本要求。我们的结果将驱动耗散光物质系统确立为探索非互易相变的一条新途径，并为非互易集体现象理论做出了贡献。
