Suppression of Decoherence at Exceptional Transitions

TL;DR

This paper demonstrates that non-Hermitian exceptional points can be used to suppress decoherence in quantum systems, contrasting with traditional Hermitian critical points that typically enhance decoherence.

Contribution

It reveals that approaching exceptional points in non-Hermitian environments can dramatically suppress decoherence, offering a new method for coherence control in quantum systems.

Findings

Decoherence can be suppressed at exceptional points in non-Hermitian systems.

The suppression effect is robust across multiple models.

This phenomenon is observable on current quantum simulation platforms.

Abstract

Decoherence is strongly influenced by environmental criticality, with conventional Hermitian critical points typically enhancing the loss of quantum coherence. Here, we show that this paradigm is fundamentally altered in non-Hermitian environments. Focusing on qubits coupled to non-Hermitian spin chains and interacting ultracold Fermi gases, we find that approaching exceptional points can either enhance or strongly suppress decoherence, depending on the balance between Hermitian and non-Hermitian system-environment couplings. In particular, when these couplings are comparable, decoherence is dramatically suppressed at exceptional transitions. We trace this behavior to the distinct response of the environmental ground state near non-Hermitian degeneracies and demonstrate the robustness of this effect across multiple models. Finally, we show that the predicted suppression of decoherence is directly observable on current digital quantum simulation platforms. Our results establish exceptional points as a concrete mechanism for suppressing decoherence and identify non-Hermitian criticality as a new avenue for coherence control in open quantum systems and quantum technologies.