New Material Set To Boost Quantum Tech And Biomedical Imaging

Researchers at the Institute for Quantum Computing (IQC) make new material to absorb and control light with unprecedented accuracy

A new paper from researchers at the Institute for Quantum Computing (IQC) at the University of Waterloo details the fabrication and application of a new material that can capture light and control the location of its absorption with unprecedented accuracy, advancing the development of next-generation photodetectors.

A hundred per cent light absorption is considered impossible but the Quantum Photonic Devices Lab group showed experimentally that this new material absorbed 94 per cent of the light in a spectral range known as the ‘Valley of Death’ where conventional photodetectors do not absorb light very well. This spectral range is of interest for biomedical and quantum applications. The experimental result was very close to the group’s 98 per cent theoretically predicted limit for this design.

“We are leading globally at taking a crack at this; combining material science and semiconductor physics to demonstrate a near-perfect absorber. We are combining different disciplines to make a perfect absorber in semiconductors to create the next generation of photodetectors, and we are one of the world leaders in this effort.”
-Dr. Sasan V. Grayli, the paper’s lead author.

Today’s superconducting nanowire single-photon detectors, used in quantum communications and computing, are considered the best when it comes to photodetection efficiency. But they require complex infrastructure and cryogenic setups to operate.

This new material is a step toward making semiconductors a commercially viable competitor to superconducting nanowire single-photon detectors by pushing the limits of how much light can be captured in a device and making them more energy efficient and portable. This would improve the sensitivity of detectors on satellites, drones and in remote locations, expanding the possibilities for quantum communication and sensing technologies.

“You always lose some portion of light due to reflection or other mechanisms and a new material like ours is required to get to near-unity absorption. Since we are designing these devices to absorb almost all the light, the probability of being able to detect the photon will be highly improved. We can also control the location of absorption with unprecedented accuracy, which will enhance the timing resolution of single-photon detectors beyond the physical limit that nature allows.”
-Michael Reimer, IQC Faculty and Professor, Department of Electrical and Computer engineering.

Beyond quantum technology applications, improved light absorption using this new material could also improve cameras that are used in eye-imaging, and classical photodetectors used in biomedical imaging to make cancer detection and treatment more precise.