Researchers at the University of Waterloo’s Institute for Quantum Computing have created a new material that can capture light and control the location of its absorption with unprecedented precision. This breakthrough could pave the way for next-generation light detectors to be used in quantum technologies and biomedical imaging.

While it’s considered impossible for a material to absorb 100% of the light, the Quantum Photonic Devices Lab group found that this new material could absorb 94% of the light in a spectral range known by researchers as the “Valley of Death”—an area where conventional photodetectors struggle. The experimental result was very close to the group’s predicted limit of 98%.

“We are leading globally at taking a crack at this; combining material science and semiconductor physics to demonstrate a near-perfect absorber,” says Sasan V. Grayli, the paper’s lead author. “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.”

Currently, the most efficient light detectors are superconducting nanowire single-photon detectors, which are used in quantum communication and computing. But these require complex infrastructure and cryogenic (extremely low) temperatures to operate.

This new material could make semiconductor-based detectors a practical alternative: more effective at capturing light, more energy efficient, and more portable. This would improve the sensitivity of detectors on satellites and drones and in remote locations, expanding the possibilities for quantum communication and sensing.

“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,” explains Michael Reimer, Associate Professor, Institute for Quantum Computing, Department of Electrical and Computer Engineering, University of Waterloo. “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.”

Beyond quantum technology applications, this advance could improve eye imaging cameras and biomedical imaging techniques, making cancer detection and treatment more precise.

The paper was published in the June edition of Nano Letters, a journal of the American Chemical Society.

This article was adapted and published with permission from the University of Waterloo Institute for Quantum Computing.

Photo: Institute for Quantum Computing / University of Waterloo