Multimode Quantum State Tomography Using Unbalanced Array Detection

TL;DR

This paper demonstrates a method for quantum state tomography of multiple spatial modes using unbalanced array detection, enabling simultaneous measurement of quadrature statistics without balanced detection.

Contribution

It introduces a novel unbalanced heterodyne detection technique with array detectors for multi-spatial-mode quantum state measurement, simplifying the process by avoiding balanced detection.

Findings

Successfully reconstructed quadrature statistics for 22 spatial modes

Used Fourier analysis to resolve interference patterns

Achieved simultaneous multi-mode quantum state measurement

Abstract

We measure the joint Q-function of a multi-spatial-mode field using a charge-coupled device array detector in an unbalanced heterodyne configuration. The intensity pattern formed by interference between a weak signal field and a strong local oscillator is resolved using Fourier analysis and used to reconstruct quadrature amplitude statistics for 22 spatial modes simultaneously. The local oscillator and signal propagate at an angle of 12 mrad thus shifting the classical noise to modes that do not overlap with the signal. In this configuration, balanced detection is not necessary.