PARAMETRIC HOMODYNE DETECTION:
BROADBAND  QUANTUM OPTICAL MEASUREMENT

Due to their highly multimode nature (spectrally), our sources produce an ultra-bright flux of entangled bi-photons and squeezed light, which opens new avenues for ultrafast, highly parallel processing of quantum information. However, a highly multimode measurement is critically needed to efficiently harness this bandwidth resource for quantum technology and handle the entire bandwidth simultaneously. The limiting bottleneck is the quantum coherent detection of the optical field by homodyne measurement, which is normally limited by the narrowband electronic response of standard photodetectors. Consequently, standard homodyne is inherently single mode, drastically limiting the detection rate.
To overcome this bandwidth limit we conceived and developed. Using broadband parametric amplification, we the quadrature of interest at full bandwidth and with no added noise before it is detected. We harness the non-classical phase-dependent amplification of a parametric amplifier, which either annihilates photons-pairs or stimulates their creation depending on the bi-photons phase, as an with practically unlimited bandwidth (limited only by the phase matching of the nonlinear parametric interaction). This novel broadband multimode quantum detector is key to the applications we pursue in multiplexed quantum communication, quantum-enhanced Raman sensing, Interferometric sensing of distance and rotation (Sagnac gyroscopes), photonic computation, etc.