Incorporating quantum photonic sources and single-photon detectors onto a single chip

Superconducting nanowire single-photon detectors (SNSPDs) have potential optical research applications and can serve as a platform for photonic quantum computing. Researchers have created a proof-of-principle on-chip single-photon detector that overcomes complications and limitations encountered by previous SNSPDs, demonstrating a very high efficiency and low false detection rate.

McDonald et al. created a new photonic integrated circuit that incorporates SNSPDs and quantum optical sources onto a single chip. The SNSPD detects photons from a quantum well photon source transported through a silicon waveguide, and a tungsten silicide superconducting nanowire runs along the waveguide to increase photon absorption. As the SNSPD absorbs a photon, it creates a localized hotspot and induces a small voltage pulse.

“This is a proof-of-principle with all three essential elements of photonic integrated circuits,” said author Corey McDonald.

To characterize device performance, the researchers operated the photon source, both with and without bias currents, to measure SNSPD performance and false detection rates. They also studied cross talk between adjacent SNSPDs to ensure the light is properly coupled to the waveguide, and light scattered between channels is minimized. The group found the circuit’s photon absorption probability exceeded 99.9%, and the false detection rate was very small, leading to a total device efficiency over 90%.

According to McDonald, the researchers next hope to replace the quantum well photon source with an on-chip quantum dot, which is a very pure single-photon source.

“This first proof-of-principle device uses quantum wells as photon sources, albeit not single photon sources,” McDonald said. “Our next efforts will use quantum dots instead, since they are, in fact, single-photon sources and are easily incorporated into the existing architecture we developed in this paper.”

Source: “III-V photonic integrated circuit with waveguide-coupled light-emitting diodes and WSi superconducting single-photon detectors,” by Corey McDonald, Galan Moody, Sae Woo Nam, Richard P. Mirin, Jeffrey M. Shainline, Adam McCaughan, Sonia Buckley, and Kevin L. Silverman, Applied Physics Letters (2019). The article can be accessed at https://doi.org/10.1063/1.5108893 .