Thin-film lithium niobate two-photon and four-photon quantum sources

Abstract

Thin-film lithium niobate (TFLN) has recently emerged as an ideal platform for integrated photonics owing to its broad transparency window, superior nonlinear optical characteristics, and convenience in ferroelectric domain inversion, leading to efficient quasi-phase-matched (QPM) frequency conversion processes. In particular, an efficient spontaneous parametric down-conversion (SPDC) process enables the construction of high-quality quantum entangled photon sources in future quantum computation/communication systems. Here, we demonstrate two-photon and four-photon generations based on a periodically poled TFLN waveguide. The two-photon state generator achieves high pair generation rates (PGRs) up to 7.5 MHz/ μ W with broad bandwidths beyond 60 nm. We further realize four-photon generation with a maximum rate of 3.5 Hz. This work offers high scalability and potential applications in high-dimensional entanglement and future integrated quantum information systems