Digital reconstruction of squeezed light for quantum information processing

Abstract

Squeezed light plays a vital role in quantum information processing. However, its highly sensitive nature presents significant practical challenges, particularly in remote detection, which traditionally requires complex systems such as active phase locking, clock synchronization, and polarization control. Here, we propose and demonstrate an asynchronous detection method for squeezed light eliminating the need for these complex systems. By employing radio-frequency heterodyne detection with a locally generated local oscillator and applying a series of digital unitary transformations, we successfully reconstruct squeezed states of light. We validate our approach in two key applications: the distribution of squeezed light over a 10 km fiber channel, and passive continuous-variables quantum key distribution based on squeezed vacuum states between two labs connected via deployed fiber. This demonstrates a practical digital reconstruction method for squeezed light, opening new avenues for practical distributed quantum sensing networks and high-performance, long-distance quantum communication using squeezed states.