Dispersion-enabled quantum state control in integrated photonics

TL;DR

This paper explores how the inherent dispersion in integrated photonic devices can be harnessed to achieve advanced quantum state control, enabling new functionalities like tunable entanglement and photon timing in quantum circuits.

Contribution

It demonstrates novel dispersion-based capabilities in integrated photonics, including in-situ entanglement control and tunable two-photon interference, expanding the potential of on-chip quantum devices.

Findings

Dispersion enables in-situ control over photon entanglement.

Tunable photon time-ordering and entanglement-sensitive coincidence generation.

Maintains perfect two-photon anti-coalescence while tuning interference visibility.

Abstract

Integrated optics has brought unprecedented levels of stability and performance to quantum photonic circuits. However, integrated devices are not merely micron-scale equivalents of their bulk-optics counterparts. By exploiting the inherently dispersive characteristics of the integrated setting, such devices can play a remarkably more versatile role in quantum circuit architectures. We show this by examining the implications of linear dispersion in an ordinary directional coupler. Dispersion unlocks several novel capabilities for this device, including in-situ control over photon spectral and polarization entanglement, tunable photon time-ordering, and entanglement-sensitive two-photon coincidence generation. Also revealed is an ability to maintain perfect two-photon anti-coalescence while tuning the interference visibility, which has no equivalent in bulk-optics. The outcome of this work adds to a suite of state engineering and characterization tools that benefit from the advantages of integration. It also paves the way for re-evaluating the possibilities offered by dispersion in other on-chip devices.