Slow light on a chip

J. Capmany, Ivana Gasulla, Salvador Sales

Bin Wu, John F. Hulbert, Katie Hurd +2 more

Hollow-core waveguides form the foundation of a new class of atomic spectroscopy chips that allows for large light-matter interactions at ultralow power levels [1-3]. We will review the development of a chip-scale platform for large quantum interference effects in hot rubidium vapor [4]. These include 44% optical transparency and a group index of 1,200. The concomitant reduction in the group velocity of light results in the largest slow light effects observed in waveguide-based environments to date.

Hiroki Takesue, Nobuyuki Matsuda, Eiichi Kuramochi +1 more

We report the first entanglement generation experiment using an on-chip slow light device. With highly efficient spontaneous four-wave mixing enhanced by the slow light effect in a coupled resonator optical waveguide based on a silicon photonic crystal, we generated 1.5-μm-band high-dimensional time-bin entangled photon pairs. We undertook two-photon interference experiments and observed the coincidence fringes with visibilities >74%. The present result enables us to realize an on-chip entanglement source with a very small footprint, which is an essential function for quantum information processing based on integrated quantum photonics.

Sidney Perkowitz

Sidney Perkowitz

Giraud Carrier, Chollet Matthieu

The focus of this work is the integration of alkali vapor atomic vapor cells into common silicon wafer microfabrication processes. Such integrated platforms enable the study of quantum coherence effects such as electromagnetically induced transparency, which can in turn be used to demonstrate slow light. Slow and stopped light devices have applications in the optical communications and quantum computing fields. This project uses hollow core anti-resonant reflecting optical waveguides (ARROWs) to build such slow light devices. An explanation of light-matter interactions and the physics of slow light is first provided, as well as a detailed overview of the fabrication process. Following the discovery of a vapor transport issue, a custom capillary-based testing platform is developed to quantify the effect of confinement, temperature, and wall coatings on rubidium transport. A mathematical model is derived from the experimental results and predicts long transport times. A new design methodology is presented that addresses the transport problem by increasing the number of rubidium entry points. This design also improves chip durability and decreases environmental susceptibility through the use of a single copper reservoir and buried channel waveguides (BCWs). New chips are successfully fabricated, loaded, and monitored for rubidium spectra. Absorption is observed in several chips and absorption peaks depths in excess of 10% are reported. The chip lifetime remains comparable to previous designs. This new design can be expanded to a multi-core platform suitable for slow and stopped light experimentation.