Tuning between photon-number and quadrature measurements with weak-field homodyne detection
Guillaume Thekkadath, D. S. Phillips, Jacob F. F. Bulmer, William R. Clements, A. Eckstein, Bryn A. Bell, Jasleen Lugani, Tom A. W. Wolterink, Adriana E. Lita, Sae Woo Nam, Thomas Gerrits, C. G. Wade, Ian A. Walmsley
Abstract
Variable measurement operators enable the optimization of strategies for testing quantum properties and the preparation of a range of quantum states. Here, we experimentally implement a weak-field homodyne detector that can continuously tune between measuring photon numbers and field quadratures. We combine a quantum signal with a coherent state on a balanced beam splitter and detect light at both output ports using photon-number-resolving transition edge sensors. We observe that the discrete difference statistics converge to the quadrature distribution of the signal as we increase the coherent state amplitude. Moreover, in a proof-of-principle demonstration of state engineering, we show the ability to control the photon-number distribution of a state that is heralded using our weak-field homodyne detector.