Design and fabrication of an integrated photonic circuit for producing a maximally-entangled three-photon state

Mauricio Gómez-Robles, Rafael Salas‐Montiel, Roberto Ramírez-Alarcón

Alexander Miloshevsky, Lucas M. Cohen, Karthik V. Myilswamy +5 more

We present a CMOS-fabricated photonic integrated circuit tailored to the generation of ultrabroadband polarization-entangled photons. This fully on-chip source leverages a novel design combining polarization splitter-rotators and a bidirectionally pumped microring resonator to produce high-fidelity polarization Bell states over 115 frequency-bin pairs spaced 38.4 GHz apart.

Jonathan C. F. Matthews, Alberto Politi, André Stefanov +14 more

Nienke ten Haaf, D.P. van der Vuurst, David L. Bakker +3 more

Photonic integrated circuits (PICs) based on silicon-on-insulator (SOI) substrates provide a lightweight, compact platform for applications in quantum optics. We show the evaluation and characterization of an SOI-bascd PIC design for an entangled photon pair source, generating photon pairs by means of the nonlinear process of spontaneous four-wave mixing in microring resonators. Experimental results following from the chip fabrication fed back into the simulated parameter tuning effects, culminating in photon pair generation with measured correlations exceeding classically predicted limits.

Jonathan C. F. Matthews, Alberto Politi, Anthony Laing +12 more

Jessica César-Cuello, Isabel Carnoto Amat, Luis Enrique García-Muñoz +1 more

Quantum transducers are key components for hybrid quantum networks, enabling the transfer of quantum states between microwave and optical photons. In the quantum community, many efforts have focused on creating and verifying the entanglement between microwave and optical fields in systems that typically operate at temperatures in the millikelvin range. Our goal is to develop an integrated microwave optical entanglement device based on a lithium niobate whispering gallery mode resonator (WGMR). To investigate the feasibility of developing such an integrated device, first, a passive photonic integrated circuit (PIC) was designed, fabricated, and characterized. The PIC was developed on a thin-film lithium niobate (TFLN) on an insulator platform, and it includes eight ring resonators and four asymmetric Mach–Zehnder interferometers. This paper presents the design and operational principles of the integrated device for microwave–optical entanglement, as well as the results of the characterization of the passive PIC.