Hybrid quantum gate and entanglement between a "stationary" photonic qubit and a flying optical state via a giant cross Kerr nonlinear effect

TL;DR

This paper proposes a protocol leveraging giant cross-Kerr nonlinearity to create high-fidelity hybrid quantum gates and entanglement between stationary microwave qubits and flying optical photons, advancing quantum networking capabilities.

Contribution

It introduces a novel method for hybrid quantum gates and entanglement using cross-Kerr nonlinearity, enabling controlled-Z gates between microwave and optical photons.

Findings

High-fidelity hybrid quantum gate demonstrated

Protocol enables quantum networking between superconducting circuits

Controlled-Z gate achieved between microwave and optical photons

Abstract

Quantum information processing with hybrid protocols making use of discrete- and continuous-variable currently attracts of great interest because of its promising applications in scalable quantum computer and distant quantum network. By inducing a giant cross-Kerr nonlinearity between two cavities, we propose a general protocol for hybrid quantum gate and quantum entanglement with high fidelity between a stationary, discrete photonic qubit and a flying photonic state. Interestingly, our protocol can be used to conduct a controlled-Z quantum gate between a stationary microwave photon stored in a slowly-decaying microwave cavity and a flying optical photon, and therefore enable to build quantum network for distant superconducting quantum circuits.