Toolbox for the design of LiNbO₃-based passive and active integrated quantum circuits

Abstract

We present and discuss perspectives of current developments on advanced\nquantum optical circuits monolithically integrated in the lithium niobate\nplatform. A set of basic components comprising photon pair sources based on\nparametric down conversion (PDC), passive routing elements and active\nelectro-optically controllable switches and polarisation converters are\nbuilding blocks of a toolbox which is the basis for a broad range of diverse\nquantum circuits. We review the state-of-the-art of these components and\nprovide models that properly describe their performance in quantum circuits. As\nan example for applications of these models we discuss design issues for a\ncircuit providing on-chip two-photon interference. The circuit comprises a PDC\nsection for photon pair generation followed by an actively controllable\nmodified Mach-Zehnder structure for observing Hong-Ou-Mandel (HOM)\ninterference. The performance of such a chip is simulated theoretically by\ntaking even imperfections of the properties of the individual components into\naccount.\n