Chiral State Conversion Without Encircling An Exceptional Point

Abstract

Dynamically varying system parameters along a path enclosing an exceptional point is known to lead to chiral mode conversion. But is it necessary to include this non-Hermitian degeneracy inside the contour for this process to take place? We show that a sufficiently slow variation of parameters, even away from the system's exceptional point, can also lead to a robust asymmetric state exchange. To study this process, we consider a prototypical two-level non-Hermitian Hamiltonian with a constant coupling between elements. Closed-form solutions are obtained when the amplification or attenuation coefficients in this arrangement are varied in conjunction with the resonance detuning along a circular contour. Using asymptotic expansions, this input-independent mode conversion is theoretically proven to take place irrespective of whether the exceptional point is enclosed upon encirclement. Our results significantly broaden the range of parameter space required for the experimental realization of such chiral mode conversion processes.

Publication Date

11-27-2017

Publication Title

Physical Review A

Volume

96

Issue

5

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1103/PhysRevA.96.052129

Socpus ID

85036637719 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85036637719

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