Sequential measurement of conjugate variables as an alternative quantum state tomography

TL;DR

This paper proposes a method for quantum state tomography by sequentially measuring conjugate variables using the quasi-characteristic function, enabling state reconstruction through Fourier-transform techniques.

Contribution

It introduces a novel approach to quantum state tomography based on sequential measurements and the quasi-characteristic function, offering an alternative to traditional methods.

Findings

Reconstruction of quantum states from sequential measurements is feasible.

Proper measurement strength is crucial for accurate state reconstruction.

The method utilizes Fourier-transform techniques on joint probability data.

Abstract

It is shown how it is possible to reconstruct the initial state of a one-dimensional system by measuring sequentially two conjugate variables. The procedure relies on the quasi-characteristic function, the Fourier-transform of the Wigner quasi-probability. The proper characteristic function obtained by Fourier-transforming the experimentally accessible joint probability of observing "position" then "momentum" (or vice versa) can be expressed as a product of the quasi-characteristic function of the two detectors and that, unknown, of the quantum system. This allows state reconstruction through the sequence: data collection, Fourier-transform, algebraic operation, inverse Fourier-transform. The strength of the measurement should be intermediate for the procedure to work.