  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.
