Persistent energy-time entanglement covering multiple resonances of an on-chip biphoton frequency comb

TL;DR

This paper explores the properties of an on-chip biphoton frequency comb generated from a silicon nitride resonator, demonstrating its complex energy-time entanglement and potential for quantum communication applications.

Contribution

It provides the first detailed analysis of multi-resonance energy-time entanglement in a chip-scale biphoton frequency comb using a Franson interferometer and Schmidt mode decomposition.

Findings

Multiple frequency modes cause interference pattern modulation

The entangled state spans multiple pair-wise modes

Nonlocal dispersion cancellation demonstrated

Abstract

We investigate the time-frequency signatures of an on-chip biphoton frequency comb (BFC) generated from a silicon nitride microring resonator. Using a Franson interferometer, we examine the multifrequency nature of the photon pair source in a time entanglement measurement scheme; having multiple frequency modes from the BFC results in a modulation of the interference pattern. This measurement together with a Schmidt mode decomposition shows that the generated continuous variable energy-time entangled state spans multiple pair-wise modes. Additionally, we demonstrate nonlocal dispersion cancellation, a foundational concept in time-energy entanglement, suggesting the potential of the chip-scale BFC for large-alphabet quantum key distribution.