Optical synthesis of large-amplitude squeezed coherent-state superpositions with minimal resources

TL;DR

This paper introduces a new protocol for creating large-amplitude squeezed coherent-state superpositions using minimal resources, combining experimental implementation with high fidelity results for quantum information applications.

Contribution

The paper presents a novel, resource-efficient method for engineering heralded optical coherent-state superpositions with experimental validation.

Findings

Achieved 67% fidelity with a squeezed even coherent-state superposition

Demonstrated the creation of superpositions with size ||^2=3

Protocol facilitates future quantum information and fundamental tests

Abstract

We propose and experimentally realize a novel versatile protocol that allows the quantum state engineering of heralded optical coherent-state superpositions. This scheme relies on a two-mode squeezed state, linear mixing and a $n$-photon detection. It is optimally using expensive non-Gaussian resources to build up only the key non-Gaussian part of the targeted state. In the experimental case of a two-photon detection based on high-efficiency superconducting nanowire single-photon detectors, the freely propagating state exhibits a 67% fidelity with a squeezed even coherent-state superposition with a size $|\alpha|^2$=3. The demonstrated procedure and the achieved rate will facilitate the use of such superpositions in subsequent protocols, including fundamental tests and optical hybrid quantum information implementations.