We speak to Xu Yi, who is leading Darpa-funded research seeking to exceed the quantum detection limit by up to 40 times
The University of Virginia has been awarded an $8 million grant from the Defense Advanced Research Projects Agency (Darpa) to lead a project aimed at developing next-generation optical detectors.
This effort, part of Darpa’s INSPIRED programme (INtensity-Squeezed Photonic Integration for Revolutionary Detectors), will develop chip-scale photonic systems capable of significantly enhancing sensitivity.
The technology is expected to enhance systems that rely on precise detection, such as communications, defence and medical diagnostics.
The team will employ ‘squeezed light’ — a type of quantum light that reduces detection noise — to build systems that can detect fainter signals, even amidst interference, and with much higher accuracy.
Their goal is to exceed the quantum limit by up to 40 times, using state-of-the-art silicon nitride (SiN) photonic circuits, integrated lasers and microresonators.
How will the new detectors work? What optical components will they use?
The new detectors will leverage quantum squeezed light to increase the sensitivity of signal detection. Squeezed light has been used in many scenarios to improve sensor sensitivity beyond the standard quantum limit.
One famous example is its use to enhance the sensitivity of LIGO for gravitational wave detection. The new detector will be miniaturized and a squeezed light generator will be developed using integrated photonics to enable volume production of such detectors.
Why is it possible to envision these high-sensitivity optical detectors now? What advances have made this possible?
Recent advances in integrated photonics, particularly in nonlinear optics, make such envision possible. Key to the squeezed light generation is nonlinear optics process like parametric amplification or parametric oscillation, which have been demonstrated across multiple photonic material platforms.
Several groups, including ours at UVA, have taken a step forward and shown squeezed light generation with integrated photonics. These progresses make the program envision look feasible.
What are the current and next stages of development for the chip-scale photonic devices?
Individual components on the chip-scale have shown amazing progress in the past decade or two, such as lasers, amplifiers, nonlinear photonic devices, electro-optics modulators and photodiodes. One of the directions for the current or next stages is their seamless integration to enable new photonic applications.
The Darpa ‘INSPIRED’ programme is such a good example where many state-of-the-art chip-scale devices need to be integrated together with near zero loss for a chip-scale squeezed light enhanced detectors that don’t exist at the moment.
If you had a magic wand, what optical advance would you magic into existence to aid this project?
Zero loss connection among different photonic components and photonic platforms (lasers, nonlinear resonators, optical modulators, and photodiodes). Loss is the biggest enemy to quantum light. If they magically disappeared, then everything will become much easier.
What optical equipment do you wish existed that could help your research?
Affordable hybrid integration and packaging tools for photonic chips.
How do you work with photonics companies currently, and how could this be improved?
We mostly purchase their commercial off-the-shelf (COTS) products, and from time to time we get involved in the R&D runs. We wish to participate more in the R&D runs and have a closer connection with these companies in their product developing phase.
