The combination of silicon photonics technologies and quantum technologies is very seductive. It can mean that the established infrastructure of semiconductor manufacturing could be leveraged for high-volume manufacturing of chips with quantum-technology elements.
This, of course, depends on exquisite construction and performance of the factory equipment. And it requires rigorous testing of designs from the earliest prototype chips to final production. In fact, the interval between those two phases of testing can be years. But, when a product reaches that stage, it means production is within sight!
The most important electrical and photonic testing begins at the wafer level. This is certainly useful during engineering and development and is absolutely critical for production economics once the design has advanced to volume manufacturing. After all, most of the cost of a packaged chip is in its packaging, so allowing a faulty chip to proceed through packaging is an expensive error.
Wafer probers are common, but wafer probers capable of high-throughput photonic testing are elite entrants in the field, available from just a handful of qualified manufacturers. Pioneering photonic wafer prober manufacturer FormFactor has optimized its fast photonic probers for testing of quantum computing chips.
The news that quantum-computing wafers were already undergoing wafer-level testing caught many industry observers by surprise. It means the path to volume manufacturing is clarifying... and short.