Joint quantum measurement using unbalanced array detection

Abstract

Here we describe an experiment that measures the joint statistics of a multitemporal mode field. This experiment is based on a recent proposal [1], however, rather than using balanced heterodyne detection with array detectors, here we perform unbalanced detection. This allows a significant reduction in experimental complexity, as it simplifies alignment and avoids the need to obtain proper registration between corresponding pixels whose outputs need to be subtracted. Balancing is typically used to greatly reduce the degradation caused by classical noise on the local oscillator (LO) [2]. In our experiments we operate at the shotnoise level (SNL) without balancing. We are able to do this because we use an array detector, which demonstrates one more advantage to using array detectors [1,3,4]. The mode statistics are expressed in terms of the joint Q-function of the modes Q _(xp,yp) [1,5].