Experimental Witness of Quantum Jump Induced High-Order Liouvillian Exceptional Points

TL;DR

This paper reports the first experimental observation of third-order Liouvillian exceptional points caused by quantum jumps in a two-level ultracold ion system, revealing new non-Hermitian quantum phenomena involving decay and dephasing.

Contribution

It provides the first experimental confirmation of high-order LEPs induced by quantum jumps and explores their behavior under combined decay and dephasing effects.

Findings

First observation of third-order LEPs from quantum jumps.

Demonstration of LEP movement due to decay and dephasing competition.

Insights into non-Hermitian quantum dynamics and potential applications.

Abstract

The exceptional point has presented considerably interesting and counterintuitive phenomena associated with nonreciprocity, precision measurement, and topological dynamics. The Liouvillian exceptional point (LEP), involving the interplay of energy loss and decoherence inherently relevant to quantum jumps, has recently drawn much attention due to capability to fully capture quantum system dynamics and naturally facilitate non-Hermitian quantum investigations. It was also predicted that quantum jumps could give rise to third-order LEPs in two-level quantum systems for its high dimensional Liouvillian superoperator, which, however, has never been experimentally confirmed until now. Here we report the first observation of the third-order LEPs emerging from quantum jumps in an ultracold two-level trapped-ion system. Moreover, by combining decay with dephasing processes, we present the first experimental exploration of LEPs involving combinatorial effect of decay and dephasing. In particular, due to non-commutativity between the Lindblad superoperators governing LEPs for decay and dephasing, we witness the movement of LEPs driven by the competition between decay and dephasing occurring in an open quantum system. This unique feature of non-Hermitian quantum systems paves a new avenue for modifying nonreciprocity, enhancing precision measurement, and manipulating topological dynamics by tuning the LEPs.