Integrated photon-pair source with monolithic piezoelectric frequency tunability

This work demonstrates the capabilities of an entangled photon-pair source at telecom wavelengths, based on a photonic integrated Si$_3$N$_4$ microresonator with monolithically piezoelectric frequency tuning. Previously, tuning photon-pairs generated by microresonators has only been demonstrated using thermal control, however these have limited actuation bandwidth, and are not compatible cryogenic environments. Here, frequency-tunable generation aluminium nitride layer shown. Fast-frequency locking to external laser is demonstrated, resulting bandwidth orders magnitude larger than reported previously locking. These abilities will direct application in future schemes which interface such sources quantum memories e.g. trapped-ion or rare-earth ion schemes.