Generating and detecting entangled cat states in dissipatively coupled degenerate optical parametric oscillators

TL;DR

This paper demonstrates that dissipative coupling between degenerate optical parametric oscillators can naturally generate two-mode entangled cat states, providing a promising platform for quantum information and foundational tests.

Contribution

It introduces a method to produce two-mode entangled cat states via dissipative coupling, extending single-mode cat state generation in optical parametric oscillators.

Findings

Two-mode entangled cat states can be generated without additional hurdles.

A variance-based criterion effectively detects cat-state entanglement.

Numerical simulations identify parameter regimes for successful state generation.

Abstract

Non-Gaussian continuous variable states play a central role both in the foundations of quantum theory and for emergent quantum technologies. In particular, "cat states", i.e., two-component macroscopic quantum superpositions, embody quantum coherence in an accessible way and can be harnessed for fundamental tests and quantum information tasks alike. Degenerate optical parametric oscillators can naturally produce single-mode cat states and thus represent a promising platform for their realization and harnessing. We show that a dissipative coupling between degenerate optical parametric oscillators extends this to two-mode entangled cat states, i.e., two-mode entangled cat states are naturally produced under such dissipative coupling. While overcoming single-photon loss still represents a major challenge towards the realization of sufficiently pure single-mode cat states in degenerate optical parametric oscillators, we show that the generation of two-mode entangled cat states under such dissipative coupling can then be achieved without additional hurdles. We numerically explore the parameter regime for the successful generation of transient two-mode entangled cat states in two dissipatively coupled degenerate optical parametric oscillators. To certify the cat-state entanglement, we employ a tailored, variance-based entanglement criterion, which can robustly detect cat-state entanglement under realistic conditions.