Describing a Quantum Channel by State Tomography of a Single Probe State

TL;DR

This paper introduces a method to characterize any quantum channel by performing state tomography on a single probe state, simplifying the process of understanding quantum state evolution through noisy channels.

Contribution

It presents a general law that describes quantum state evolution via a single probe state, enabling complete characterization of quantum channels with minimal experimental effort.

Findings

Single probe state tomography suffices to describe quantum channel effects

Simplifies experimental procedures for quantum channel analysis

Applicable to both known and unknown noisy quantum channels

Abstract

A general law is presented for (composite) quantum systems which directly describes the time evolution of quantum states (with one or both components) through an arbitrary noisy quantum channel. It is shown that the time evolution of all quantum states through a quantum channel can be completely captured by the evolution of a single 'probe state'. Thus in order to grasp the information of the final output states subject to a quantum channel, especially an unknown one, it only requires quantum state tomography of a single probe state, which dramatically simplifies the practical operations in experiment.