Qubit-based momentum measurement of a particle

TL;DR

This paper models quantum measurement pointers as qubits coupled to a free particle, demonstrating how to reconstruct the particle's momentum distribution using entangled pointers to simplify the process.

Contribution

It introduces a qubit-based model for quantum momentum measurement and shows how initial entanglement among pointers enhances reconstruction efficiency.

Findings

Reconstruction of momentum distribution via pointer expectation values.

Entangled pointers significantly simplify the measurement process.

Heisenberg dynamics enable linking pointer observables to particle momentum.

Abstract

An early approach to include pointers representing measurement devices into quantum mechanics was given by von Neumann. Based on this idea, we model such pointers by qubits and couple them to a free particle, in analogy to a classical time-of-flight arrangement. The corresponding Heisenberg dynamics leads to pointer observables whose expectation values allow us to reconstruct the particle's momentum distribution via the characteristic function. We investigate different initial qubit states and find that such a reconstruction can be considerably simplified by initially entangled pointers.