Stability and stabilization of unstable condensates

TL;DR

This paper investigates the stability of bosonic condensates in excited modes, exploring how interactions, system models, and external driving influence their stability, with implications for superfluid circuits and quantum control techniques.

Contribution

It presents new insights into stabilizing unstable condensates using periodic or noisy driving, extending understanding beyond ground-state stability.

Findings

Repulsive interactions stabilize ground-state condensates.

Excited mode condensates can be stabilized via external driving.

External driving methods include Kapitza and Zeno effects.

Abstract

It is possible to condense a macroscopic number of bosons into a single mode. Adding interactions the question arises whether the condensate is stable. For repulsive interaction the answer is positive with regard to the ground-state, but what about a condensation in an excited mode? We discuss some results that have been obtained for a 2-mode bosonic Josephson junction, and for a 3-mode minimal-model of a superfluid circuit. Additionally we mention the possibility to stabilize an unstable condensate by introducing periodic or noisy driving into the system: this is due to the Kapitza and the Zeno effects.