A New Superconducting Camera can Resolve Single Photons

Researchers have built a superconducting camera with 400,000 pixels, which is so sensitive it can detect single photons. It comprises a grid of superconducting wires with no resistance until a photon strikes one or more wires. This shuts down the superconductivity in the grid, sending a signal. By combining the locations and intensities of the signals, the camera generates an image.

The researchers who built the camera, from the US National Institute of Standards and Technology (NIST) say the architecture is scalable, and so this current iteration paves the way for even larger-format superconducting cameras that could make detections across a wide range of the electromagnetic spectrum.  This would be ideal for astronomical ventures such as imaging faint galaxies or extrasolar planets, as well as biomedical research using near-infrared light to peer into human tissue.

These devices have been possible for decades but with a fraction of the pixel count. This new version has 400 times more pixels than any other device of its type. Previous versions have not been very practical because of the low-quality output.

In the past, it was found to be difficult-to-impossible to chill the camera’s superconducting components – which would be hundreds of thousands of wires – by connecting them each to a cooling system.

According to NIST, researchers Adam McCaughan and Bakhrom Oripov and their collaborators at NASA’s Jet Propulsion Laboratory in Pasadena, California, and the University of Colorado Boulder overcame that obstacle by constructing the wires to form multiple rows and columns, like those in a tic-tac-toe game, where each intersection point is a pixel. Then they combined the signals from many pixels onto just a few room-temperature readout nanowires.

The detectors can discern differences in the arrival time of signals as short as 50 trillionths of a second. They can also detect up to 100,000 photons a second striking the grid.

McCaughan said the readout technology can easily be scaled up for even larger cameras, and predicted that a superconducting single-photon camera with tens or hundreds of millions of pixels could soon be available.

In the meantime, the team plans to improve the sensitivity of their prototype camera so that it can capture virtually every incoming photon. That will enable the camera to tackle quantum imaging techniques that could be a game changer for many fields, including astronomy and medical imaging.

The team’s research was published in Nature.