State Tomography of a Qubit through Scattering of a Probe Qubit

TL;DR

This paper proposes methods for reconstructing the state of a qubit by analyzing how a probe qubit scatters off it in one dimension, utilizing both spin and spatial degrees of freedom for tomography.

Contribution

It introduces two novel strategies for qubit state tomography using scattering, highlighting the utility of the probe's spatial degree of freedom.

Findings

Spatial degree of freedom aids in tomography

Two strategies using different probe degrees of freedom

Effective reconstruction of mixed qubit states

Abstract

We discuss the state tomography of a fixed qubit (a spin-1/2 target particle), which is in general in a mixed state, through 1D scattering of a probe qubit off the target. Two strategies are presented, by making use of different degrees of freedom of the probe, spin and momentum. Remarkably, the spatial degree of freedom of the probe can be useful for the tomography of the qubit.