Generating Large Cats with Nine Lives: Long-Lived Macroscopically Distinct Superposition States in Atomic Ensembles

TL;DR

This paper introduces a method to generate and stabilize long-lived macroscopic quantum superposition states in atomic ensembles, achieving lifetimes up to tens of milliseconds, significantly longer than photonic counterparts, with potential applications in quantum technologies.

Contribution

The authors demonstrate a novel approach using a quantum parametric amplifier to create and sustain atomic Schrödinger cat states with unprecedented longevity.

Findings

Atomic cat states can last up to tens of milliseconds, 4 orders longer than photonic states.

Lifetime limited to several seconds by weak spin relaxation and thermal noise.

Method opens pathways for large, long-lived quantum superpositions in atomic systems.

Abstract

We propose to create and stabilize long-lived macroscopic quantum superposition states in atomic ensembles. We show that using a fully quantum parametric amplifier can cause the simultaneous decay of two atoms and, in turn, create stabilized atomic Schr\"{o}dinger cat states. Remarkably, even with modest parameters these intracavity atomic cat states can have an extremely long lifetime, up to \emph{4 orders of magnitude} longer than that of intracavity photonic cat states under the same parameter conditions, reaching \emph{tens of milliseconds}. This lifetime of atomic cat states is ultimately limited to \emph{several seconds} by extremely weak spin relaxation and thermal noise. Our work opens up a new way toward the long-standing goal of generating large-size and long-lived cat states, with immediate interests both in fundamental studies and noise-immune quantum technologies.