Multimode quantum state tomography – in PRA

The measured Q-function for a weak coherent state.

The measured Q-function for a weak coherent state.

The latest paper from my lab at Pacific appears this week in Physical Review A. Multimode quantum state tomography using unbalanced array detection describes a technique we have developed to measure the quantum state of multiple optical modes simultaneously. We are currently working to apply this technique to slow and stored light systems where it will help us characterize the fidelity of optical memory devices.

Abstract — We measure the joint Q function of a multispatial-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.


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