Quantum interference between two single photons of different microwave frequencies

TL;DR

This paper demonstrates quantum interference and entanglement between two microwave photons of different frequencies using a superconducting resonator and parametric frequency conversion, advancing quantum information processing capabilities.

Contribution

It introduces a method to achieve quantum interference between photons of different microwave frequencies via parametric frequency conversion in a superconducting resonator.

Findings

Successful measurement of quantum interference between microwave photons of different frequencies

High-fidelity two-photon entanglement operation demonstrated

Frequency conversion enables interaction between disparate microwave modes

Abstract

We have measured quantum interference between two single microwave photons trapped in a superconducting resonator, whose frequencies are initially about 6 GHz apart. We accomplish this by use of a parametric frequency conversion process that mixes the mode currents of two cavity harmonics through a superconducting quantum interference device, and demonstrate that a two-photon entanglement operation can be performed with high fidelity.