Dual-Path Methods for Propagating Quantum Microwaves

TL;DR

This paper introduces dual-path methods for quantum microwave analysis, enabling robust quantum state tomography, entanglement detection, and noise reconstruction despite amplifier noise, advancing quantum communication technologies.

Contribution

The paper presents novel dual-path schemes for quantum microwave signal processing that are noise-tolerant and improve upon single-path methods, facilitating quantum teleportation and communication.

Findings

Methods are tolerant to amplifier noise.

Numerical and experimental validation of techniques.

Comparison with single-path scheme shows advantages.

Abstract

We study quantum state tomography, entanglement detection, and channel noise reconstruction of propagating quantum microwaves via dual-path methods. The presented schemes make use of the following key elements: propagation channels, beam splitters, linear amplifiers, and field quadrature detectors. Remarkably, our methods are tolerant to the ubiquitous noise added to the signals by phase-insensitive microwave amplifiers. Furthermore, we analyze our techniques with numerical examples and experimental data, and compare them with the scheme developed in Eichler $et$ $al$ (2011 Phys. Rev. Lett. 106 220503; 2011 Phys. Rev. Lett. 107 113601), based on a single path. Our methods provide key toolbox components that may pave the way towards quantum microwave teleportation and communication protocols.