Ground-state selection via many-body superradiant decay

TL;DR

This paper demonstrates that in many-body open quantum systems, the dominant ground state can be preferentially populated through superradiant decay, enabling near-deterministic state preparation and control.

Contribution

It introduces an exactly solvable model for many-body superradiant decay and shows how interactions favor a single ground state, surpassing single-particle branching ratios.

Findings

Occupation probability of the dominant ground state approaches unity with increasing system size.

The model is exactly solvable under permutation symmetry for any number of channels.

Analytical results show a power-law convergence of the dominant transition ratio to unity.

Abstract

For a single particle, relaxation into different ground states is governed by fixed branching ratios determined by the transition matrix element and the environment. Here, we show that in many-body open quantum systems the occupation probability of one ground state can be boosted well beyond what is dictated by single-particle branching ratios. Despite the competition, interactions suppress all but the dominant decay transition, leading to a 'winner takes all' dynamic where the system primarily settles into the dominant ground state. We prove that, in the presence of permutation symmetry, this problem is exactly solvable for any number of competing channels. Additionally, we develop an approximate model for the dynamics by mapping the evolution onto a fluid continuity equation, and analytically demonstrate that the dominant transition ratio converges to unity as a power law with increasing system size, for any branching ratios. This near-deterministic preparation of the dominant ground state has broad applicability. As an example, we discuss a protocol for molecular photoassociation where collective dynamics effectively acts as a catalyst, amplifying the yield in a specific final state. Our results open new avenues for many-body strategies in the preparation and control of quantum systems.