Entanglement and Quantum-Enhanced Sensing

Time correlations between photons are at the heart of quantum networking protocols and distributed quantum computing [1]. However, measurements of correlations at the single photon level are often hindered due to a lack of fine time resolution of the electronic control stack. The Qubit Timetag Module (QTM) solves these issues by combining state-of-the-art time resolution of 20 ps in an integrated and scalable hardware setup, which enables low-latency photon-based feedback. This simplifies the electronic needs in the field of quantum optics and networking and opens the door to large-scale quantum networks that rely on fast control flows.

The QTM is demonstrated in a large-distance photon-coincidence experiment, in collaboration with the Netherlands Organization for Applied Scientific Research (TNO). We measure photon correlations from two detectors that are separated by an effective travel path of 220 m, that includes 150 m of free space travel. The QTM’s windowed acquisition was leveraged to eliminate dark counts, resulting in a clear correlation peak despite the presence of inherent imperfections such as weak signals and background noise. The QTM simplifies and streamlines such experiments ensuring precise and efficient photon detection.

[1] Pittman, Todd (2013). "It's a Good Time for Time-Bin Qubits". Physics. 6: 110