Nanowerk February 25, 2024
Superconducting nanowire single-photon detectors (SNSPDs) have been widely used to study the discrete nature of quantum states of light in the form of photon-counting experiments. Researchers in Germany showed that SNSPDs can also be used to study continuous variables of optical quantum states by performing homodyne detection at a bandwidth of 400 kHz. By measuring the interference of a continuous-wave field of a local oscillator with the field of the vacuum state using two SNSPDs, they showed that the variance of the difference in count rates was linearly proportional to the photon flux of the local oscillator over almost five orders of magnitude. The resulting shot-noise clearance was the highest reported clearance for a balanced optical homodyne detector, demonstrating their potential for measuring highly squeezed states in the continuous-wave regime. From the joint click counting statistics, they measured the phase-dependent quadrature of a weak coherent state to demonstrate their device’s functionality as a homodyne detector… read more. Open Access TECHNICAL ARTICLEÂ
Setup used to investigate the linearity of two SNSPDs in terms of the local oscillator photon flux. … Credit: Optica Quantum Vol. 2, Issue 1, pp. 1-6 (2024)