Generating a Schr\"odinger-cat-like state via a coherent superposition of photonic operations

TL;DR

This paper presents a practical optical scheme to generate large Schr"odinger-cat-like states using photonic superpositions, employing existing laboratory components and considering realistic detector inefficiencies.

Contribution

The authors introduce a novel interferometric setup combining a nondegenerate optical parametric amplifier and beam splitters to produce superpositions of coherent states conditionally, with analysis of realistic detector effects.

Findings

High quantum fidelity achieved in state generation

Effective enhancement of superposition size demonstrated

Robustness against detector inefficiencies shown

Abstract

We propose an optical scheme to generate a superposition of coherent states with enhanced size adopting an interferometric setting at the single-photon level currently available in the laboratory. Our scheme employs a nondegenerate optical parametric amplifier together with two beam splitters so that the detection of single photons at the output conditionally implements the desired superposition of second-order photonic operations. We analyze our proposed scheme by considering realistic on-off photodetectors with nonideal efficiency in heralding the success of conditional events. A high-quality performance of our scheme is demonstrated in view of various criteria such as quantum fidelity, mean output energy, and measure of quantum interference.