When there is a small change in the shape and composition of two quantum systems that were intended to be exactly the same, a smaller but still critical frequency mismatch appears. These laser pointer changes cause the photons produced by the system to be slightly different in frequency rather than the exact copy that a quantum communication network may require.
This new photon frequency converter, as an example of nanophotonic engineering, solves these two problems at the same time, the magazine reported. The key component of the chip integrated device is a tiny ring resonant cavity with a diameter of about 80 microns (slightly smaller than the width of a human hair) and a thickness of a few tenths of a micron.
The shape and size of this ring made of silicon nitride have been optimized to improve the material’s natural characteristics of converting light from one frequency to another. This ring cavity is driven by two pump lasers, each laser working at an independent frequency. In a system called four-wave mixing Bragg scattering, the frequency of a photon entering the ring resonator will change by an amount equal to the frequency difference between the two pump lasers.
Just like riding a bicycle on a race track, the incident light has circulated hundreds of times before exiting the resonator, which greatly improves the device’s ability to convert photon frequencies at low power and low background noise. Unlike previous experiments that require a few watts of power, this system only consumes about a few percent of watts. More importantly, the amount of added noise is low enough so that it can be used in future experiments using single-photon sources.
Although other green laser pointer technologies have been applied to frequency conversion, nanophotonic technology also has its benefits. It may make the device smaller, easier to customize, lower power consumption, and compatible with mass manufacturing technology. Our job is The first demonstration of nanophotonics technology suitable for this difficult quantum frequency conversion task. This work was done by researchers from the NIST Center for Nano Science and Technology.