Interaction-induced double-sided skin effect in an exciton-polariton system

Abstract

Interaction-induced double-sided skin effect in an exciton-polariton system. Physical

Amplification of quantum signals by the non-Hermitian skin effect

“…Both the original theoretical formulation of the NHSE and the above experimental demonstrations have been based on single-particle models, applicable to non-interacting quantum particles or linear classical waves. Only recently have researchers begun to explore the NHSE beyond the single-particle regime, such as in interacting spin-less fermion chains [39] and correlated boson systems [40][41][42][43][44].…”

“…The lattices are described by bosonic quadratic Hamiltonians and can be implemented with microwave quantum circuits containing parametrically driven Josephson junctions [45,46], or other quantum optical platforms [47][48][49]. Unlike most previous studies of the NHSE in nonlinear systems [39][40][41][42], our model is based on number-nonconserving two-boson interactions. The quantum bosonic Hamiltonian lacks the nonreciprocal couplings commonly associated with the NHSE [20][21][22][24][25][26][27][28][29][30], but it can be mapped to a singleparticle Hamiltonian that is non-Hermitian and nonreciprocal via the Bogoliubov-de Gennes (BdG) transformation [50], a well-known procedure used in studying Majorana fermions [51] and topological superconductors [52].…”

“…The quantum bosonic Hamiltonian lacks the nonreciprocal couplings commonly associated with the NHSE [20][21][22][24][25][26][27][28][29][30], but it can be mapped to a singleparticle Hamiltonian that is non-Hermitian and nonreciprocal via the Bogoliubov-de Gennes (BdG) transformation [50], a well-known procedure used in studying Majorana fermions [51] and topological superconductors [52]. Previous authors have explored using the dynamics of BdG Hamiltonians for quantum amplification and related purposes [42,50,[53][54][55], and BdG Hamiltonians can even be made to exhibit distinct topological phases, giving rise to unidirectional and/or amplified topological modes [56][57][58][59][60][61][62][63][64]. While most of these studies have been theoretical, quantum amplifiers have been successfully observed in simple quantum circuits [65][66][67].…”

“…We have thus proposed a way to construct quantum amplifiers based on arrays of coupled parametrically driven resonators, using the interplay between the non-Hermitian skin effect (NHSE) [20][21][22] and the Bogoliubov-de Gennes (BdG) transformation [42][43][44]50].…”

“…The combination of the NHSE and BdG transformation has also recently featured in a study of semiclassical exciton-polariton systems [42]. Other recent theoretical works have explored the quantum bosonic case [43,44], but not the implications for quantum amplification.…”