Balanced homodyne detection with on-off detector systems: Observable nonclassicality criteria

Driven by single photon detection requirements especially for quantum information sciences, the theory of arrays of off-on detectors has been well developed and applied. However for a comprehensive characterization of nonclassicality one also needs phase sensitive properties. This missing link is fulfilled by the theory of phase sensitive click counting measurements. This theory is presented. It unifies the balanced homodyne detection for high intensities with the click detection in the few photon regime. We formulate and apply a hierarchy of nonlinear squeezing conditions to probe quantum effects beyond standard squeezing. Imperfections stemming from fluctuations of the local oscillator, detector efficiency, and dark count rates are considered. Experimentally accessible sampling formulas are given which can be applied without time consuming data processing. Our phase-sensitive click detection theory paves the way towards novel applications of nonclassical light in quantum metrology.