Unveiling and veiling a Schr\"odinger cat state from the vacuum

TL;DR

This paper proposes a method to convert virtual Schr"odinger cat states into real states in ultrastrong light-matter coupling systems, enabling observation and potential quantum information applications.

Contribution

It introduces a novel pulse-driven technique to switch between virtual and real Schr"odinger cat states in a four-level atom system with ultrastrong coupling.

Findings

Successful conversion between virtual and real cat states using ultrafast and multi-tone c6b5b6 pulses.

Potential to generate entangled cat states on demand for quantum information.

Enhanced observation of virtual states in ultrastrong coupling regimes.

Abstract

Deep in the ultrastrong light-matter coupling regime, it has been predicted that the ground state of a two-level atom interacting with a cavity mode takes the form of a "virtual" Schr\"odinger cat entangled state between light and matter. We propose a method to convert this Schr\"odinger cat state from virtual to real, and back again, by driving the atom with optimally chosen pulses. Our system consists of a four-level atom, with two of these levels ultrastrongly coupled to a cavity mode. We show that the Schr\"odinger cat state can be converted between virtual and real by making use of either an ideal ultrafast pulse or a multi-tone {\pi}-pulse. In addition to allowing us to observe these unusual virtual states this method could also be used to generate entangled cat states on demand for quantum information processing.