Arrayed squeezed light transmission and reception with a fiber-optic setup

Squeezed light is a quantum state of light that exhibits non-classical properties such as sub-shot-noise-limited variance in one of its quadratures. This nonclassicality can be leveraged to enable applications such as quantum sensing, communications and computing. Single channel generation and detection of squeezed light has been demonstrated in various platforms such as fiber optics, integrated photonics, and superconducting circuits. Arrayed generation and detection of non-classical light in large-scale architectures can enable novel functionalities such as multimode quantum state engineering and directional transmission and reception of quantum information. Here, we demonstrate an arrayed squeezed light generation and detection scheme realized with fiber optics. A 1550 nm laser is used to pump a periodically poled lithium niobate (PPLN) waveguide for second harmonic generation. The upconverted 775 nm light is split and used to pump two PPLN waveguides for Type-0 spontaneous parametric downconversion (SPDC) in two coherent channels. The resulting two-channel transmitter is connected to two homodyne detectors that detect the two squeezed modes coherently. Detected signals are then interfered in radio frequency (RF) to observe the interference pattern between the two squeezed modes.