Hybrid entanglement caused by depletion of pump on output of spontaneous parametric down converter

TL;DR

This paper introduces a novel method for generating hybrid entanglement between microscopic and macroscopic states using pump depletion in spontaneous parametric down conversion, with practical testing and enhancement strategies.

Contribution

It presents a new approach to create hybrid entanglement via pump depletion, characterizes its limits, and proposes a practical testing scheme without photon number resolving detection.

Findings

Hybrid entanglement can be generated through pump depletion.

The entanglement is weak but can be tested and enhanced.

The method is practically realizable without photon number resolving detectors.

Abstract

We consider novel method for implementation of hybrid entanglement between microscopic and macroscopic states on output of spontaneous parametric down converter through the depletion of the pump wave. The generated signal, idler and pumping fields show weak entanglement. We characterize it and show the limits of applicability of the depleted pump regime. Testing method of the hybrid entanglement is proposed. The hybrid entanglement is tested by conditional generation of maximally entangled states of two qubits and qutrits regardless of its smallness. Possibilities to enhance the hybrid entanglement and, as consequence, success probabilities of the conditional generation are considered. The optical scheme is realizable in practice and can do without photon number resolving detection.