A Bi-CMOS electronic photonic integrated circuit quantum light detector

World's smallest quantum light detector on a silicon chip
 https://www.sciencedaily.com/releases/2024/05/240517164111.htm
Source:
 University of Bristol
Summary:
 Researchers have made an important breakthrough in scaling quantum technology by integrating the world's tiniest quantum light detector onto a silicon chip.

Interesting is the circuit, figure 1 in
 https://www.science.org/doi/10.1126/sciadv.adk6890

the photo diodes dare used as pull-up and pull down to teh transistor base.

Quantum talk everywhere,
but interesting noise cancellation after the beam splitter.
Anybody knows the basics of this?