Quantum sensor monitors cancer treatments with single photon

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Researchers claim their new quantum sensor outperforms existing technologies and could lead to significant improvements in long-range 3D imaging and monitoring the success of cancer treatments.

quantum sensor
Image by skeeze on Pixabay

Developed by researchers at the University of Waterloo's Institute for Quantum Computing (IQC) in Ontario, Canada, the sensors – claimed to be the first of their kind - are based on semiconductor nanowires that can detect single particles of light with high-timing resolution, speed and efficiency over a wavelength range from ultraviolet to near-infrared.

The team at Waterloo claim also that the technology can significantly improve quantum communication and remote sensing capabilities. Similar technologies are reported to have peak efficiencies above 90 per cent and timing jitter of <30ps, but are not widely used due to their cost and cryogenic operation.

"A sensor needs to be very efficient at detecting light. In applications like quantum radar, surveillance, and night time operation, very few particles of light return to the device," said principal investigator Michael Reimer, an IQC faculty member and assistant professor in the Faculty of Engineering's electrical and computer engineering department. "In these cases, you want to be able to detect every single photon coming in."

The next generation quantum sensor designed in Reimer's lab is said to be so fast and efficient that it can absorb and detect a single photon, and refresh for the next one within nanoseconds. The researchers created an array of tapered nanowires that turn incoming photons into electric current, which is amplified and detected.

Remote sensing, high-speed imaging from space, acquiring long-range high-resolution 3D images, quantum communication, and singlet oxygen detection for dose monitoring in cancer treatment are all applications that the team believe could benefit from the single photon detection offered by the new quantum sensor.

The semiconducting nanowire array achieves its high speed, timing resolution and efficiency thanks to the quality of its materials, the number of nanowires, doping profile and the optimisation of the nanowire shape and arrangement.

The sensor detects a broad spectrum of light with high efficiency and high timing resolution, all while operating at room temperature. Reimer added that the spectrum absorption can be broadened even further with different materials.

"This device uses Indium Phosphide nanowires. Changing the material to Indium Gallium Arsenide, for example, can extend the bandwidth even further towards telecommunications wavelengths while maintaining performance," Reimer said. "It's state of the art now, with the potential for further enhancements."

Once the prototype is packaged with the right electronics and portable cooling, the sensor is ready for testing beyond the lab. "A broad range of industries and research fields will benefit from a quantum sensor with these capabilities," said Reimer.

The new sensor, developed in collaboration with researchers at the Eindhoven University of Technology, is described in a paper titled Tapered InP nanowire arrays for efficient broadband high-speed single photon detection, which is published in Nature Nanotechnology.