Southwest Quantum Information and Technology

Phase tracking and correction for non-Gaussian state discrimination measurements of coherent states

Presenting Author: Matthew DiMario, University of New Mexico CQuIC
Contributing Author(s): Francisco Becerra-Chavez

Non-Gaussian measurements for discriminating coherent states of light with different phases enable information transfer beyond what conventional technologies can achieve with an ideal Gaussian measurement, referred to as the quantum noise limit (QNL). However, random phase drifts in any real-world communication channel make the task of extracting the information encoded in the states very challenging. The current approach for overcoming this problem in conventional optical communications, based on heterodyne detection, is to perform parameter estimation in the digital domain. While this technique works in conventional communications, they are incompatible with non-Gaussian receivers. This puts in question the potential advantages of quantum receivers surpassing the conventional limits of detection in real channels with random phase drifts. We develop and demonstrate an algorithm which performs real time parameter estimation using only the data collected by the non-Gaussian discrimination measurement itself. The phase correction is applied to the local oscillator to actively and adaptively correct for any phase changes that diminish the benefit over a heterodyne measurement. Our demonstration allows non-Gaussian receivers to overcome phase drifts in real channels while enabling discrimination below QNL. This demonstration makes non-Gaussian receivers more robust and a much more practical quantum technology for future applications in communication and information processing.

(Session 5 : Sunday from 5:00pm - 7:00pm)