Southwest Quantum Information and Technology

Multimode Gaussian State Tomography With A Single Photon Counter

Presenting Author: Arik Avagyan, National Institute of Standards and Technology, Boulder
Contributing Author(s): Emanuel Knill, Scott Glancy

The continuing improvement in the qualities of photon-number-resolving detectors opens new possibilities for performing state tomography on quantum states of light. In this work we consider the question of what can be learned about an arbitrary multimode Gaussian state by a single photon-number-resolving detector that does not distinguish between modes. We find an answer to this question in the ideal case when the detector does not have a limit on the photon number resolution. In the asymptotic data limit we show that such a setup allows one to learn the eigenspectrum of the covariance matrix of the state and the absolute displacement along each eigenspace, and nothing else. We investigate the operational meaning of these parameter for pure and mixed states. We conjecture that these parameters can be learned from a finite set of photon number expectations, with the size of the set depending on the number of modes of the Gaussian state, which will make this measurement setup practical.

(Session 5 : Thursday from 12:00pm-2:00 pm)