Exceptional points in oligomer chains

Symmetry underpins our understanding of physical law. Open systems, those in contact with their environment, can provide a platform to explore parity-time symmetry. While classical parity-time symmetric systems have received a lot of attention, especially because of the associated advances in the generation and control of light, there is much more to be discovered about their quantum counterparts. Here we provide a quantum theory which describes the non-Hermitian physics of chains of coupled modes, which has applications across optics and photonics. We elucidate the origin of the exceptional points which govern the parity-time symmetry, survey their signatures in quantum transport, study their influence for correlations, and account for long-range interactions. We also find how the locations of the exceptional points evolve as a function of the chain length and chain parity, capturing how an arbitrary oligomer chain transitions from its unbroken to broken symmetric phase. Our general results provide perspectives for the experimental detection of parity-time symmetric phases in one-dimensional arrays of quantum objects, with consequences for light transport and its degree of coherence. Open quantum systems governed by non-Hermitian dynamics provide a platform to explore PT symmetric phases. Here, a general theory is derived to describe the location of exceptional points in a 1D oligomer chain of arbitrary length.

Automated summary

This article introduces a quantum theory describing the non-Hermitian physics of chains of coupled modes, elucidating the origin of exceptional points governing parity-time symmetry and their influence on quantum transport and correlations. It is found that the locations of exceptional points evolve with chain length and parity, capturing the transition from unbroken to broken symmetric phase in oligomer chains.