Frequency-modulated continuous-wave quantum interferometric lidar with enhanced accuracy and resolution

The range and velocity of a moving object can be ascertained using the sensing technique known as light detection and ranging (lidar). It has recently been suggested that quantum lidar, which uses entangled states of light, can enhance the capabilities of lidar. Entangled pulsed light is used in prior quantum lidar approaches to assess both range and velocity at the same time using the time of flight and Doppler shift. However, the detection of entangled pulsed light is often inefficient and constrained by the temporal resolution of the detectors. Here, we investigate a quantum lidar utilizing a linear interferometer operating on a frequency-modulated continuous wave (FMCW) instead of pulses. Our findings demonstrate that the quantum FMCW lidar enables simultaneous measurements of range and velocity with quantum-enhanced accuracy and resolution, as well as superresolution phase imaging. Through self-heterodyne detection with a linear optical design, the signals of the quantum FMCW lidar with entangled photon pair can be efficiently carried out electronically by down-converting the optical signal to the microwave region. As a result, it is better suited for practical implementations.