Switching off microcavity polariton condensate near the exceptional point

TL;DR

This paper demonstrates how an exceptional point in a microcavity polariton condensate allows for optical switching of the condensate state with very low laser power, revealing new control mechanisms in non-Hermitian photonics.

Contribution

It introduces the first experimental observation of an exceptional point in an exciton polariton condensate within a double-well potential, enabling optical control of the condensate.

Findings

Polariton condensate can be switched off with low-power optical excitation.

Near the exceptional point, gain and loss can be balanced to re-establish condensate.

The method offers a simple way to manipulate polariton lasing in double-well structures.

Abstract

Gain and loss modulation are ubiquitous in nature. An exceptional point arises when both the eigenvectors and eigenvalues coalesce, which in a physical system can be achieved by engineering the gain and loss coefficients, leading to a wide variety of counter-intuitive phenomena. In this work we demonstrate the existence of an exceptional point in an exciton polariton condensate in a double-well potential. Remarkably, near the exceptional point, the polariton condensate localized in one potential well can be switched off by an additional optical excitation in the other well with very low (far below threshold) laser power which surprisingly induces additional loss into the system. Increasing the power of the additional laser leads to a situation in which gain dominates in both wells again, such that the polaritons re-condense with almost the same density in the two potential wells. Our results offer a simple way to optically manipulate the polariton lasing process in a double-well potential structure. Extending such configuration to complex potential well lattices offers exciting prospects to explore high-order exceptional points and non-Hermitian topological photonics in a non-equilibrium many-body system.