New superconducting camera with 400,000 pixels offers unprecedented views of the cosmos

Superconducting camera astronomy concept

Recent breakthroughs in superconducting camera technology have led to the development of a 400,000-pixel camera that can detect weak astronomical signals. This camera, which operates with minimal noise, could revolutionize the search for Earth-like planets and improve communications in deep space through its application in NASA’s DSOC project. Credit:

A new superconducting camera with 400,000 pixels offers unprecedented possibilities in low-noise, high-resolution imaging for applications in astronomy and quantum technology.

When pursuing faint celestial bodies such as distant stars and exoplanets, and capturing them photon is essential for maximizing the scientific yield of a mission. Cameras used for this task must operate at extremely low noise levels and detect the smallest amounts of light: single photons.

Historically, while superconducting cameras have met these low-noise, high-sensitivity requirements, they have been limited by their small size, often no larger than a few thousand pixels, which limits their ability to capture high-resolution images. However, a breakthrough by a research team recently broke this barrier and created a superconducting camera with 400,000 pixels. This advance enables the detection of weak astronomical signals across a broad spectrum, from ultraviolet to infrared wavelengths.

Superconducting camera with 400,000 pixels

The superconducting camera with 400,000 pixels, based on superconducting nanowire detectors for single photons. Credit: Adam McCaughan/NIST

Although numerous other camera technologies exist, cameras that use superconducting detectors are very attractive for use in astronomical missions because of their extremely low-noise operation. When imaging faint sources, it is critical that a camera faithfully reports the amount of light received, and does not distort the amount of light received or inject its own false signals. Superconducting detectors are ideally suited to this task, thanks to their operation at low temperatures and their unique composition. As project leader Dr. Adam McCaughan describes, “with these detectors you could collect data all day long and capture billions of photons, and less than ten of those photons would be due to noise.”

Bakhrom Oripov and Ryan Morgenstern

NIST team members Bakhrom Oripov (left) and Ryan Morgenstern (right) mount the superconducting camera on a specialized cryogenic stage. Credit: Adam McCaughan/NIST

But while superconducting detectors show promise for astronomical applications, their use in that field is hampered by small camera sizes that allow for relatively few pixels. Because these detectors are so sensitive, it is difficult to fit many of them into a small area without interfering with each other. Additionally, because these detectors must be kept cold in a cryogenic refrigerator, only a handful of wires can be used to carry the signals from the camera to the warmer readout electronics.

To overcome these limitations, researchers at the National Institute of Standards and Technology (NIST), the NASA Jet Propulsion Laboratory (JPL), and the University of Colorado Boulder applied time-domain multiplexing technology to the interrogation of two-dimensional superconducting nanowire-single photon detector (SNSPD) arrays. The individual SNSPD nanowires are arranged as intersecting rows and columns. When a photon arrives, the times it takes to activate a row detector and a column detector are measured to determine which pixel sent the signal. This method allows the camera to efficiently encode the many rows and columns on just a few readout wires instead of thousands of wires.

This animation shows the newly developed readout system that allowed researchers to build a 400,000 single-wire superconducting camera, the highest resolution camera of its kind. Credit: S. Kelley/NIST

SNSPDs are one type of detector in a collection of many such superconducting detector technologies, including microwave kinetic inductance detectors (MKID), transition-edge sensors (TES), and quantum capacitance detectors (QCD). SNSPDs are unique in that they can operate much warmer than the millikelvin temperatures required by those other technologies, and can have extremely good timing resolution, although they are unable to resolve the color of individual photons. SNSPDs have been jointly researched by NIST, JPL, and others in the community for nearly two decades, and this latest work was only possible because of the advances generated by the broader superconducting detector community.

Once the team implemented this readout architecture, they found that it immediately became easy to build superconducting cameras with extremely large numbers of pixels. As technical leader Dr. Bakhrom Oripov describes: “The big advance here is that the detectors are truly independent, so if you want a camera with more pixels, you just add more detectors to the chip.” The researchers note that while their recent project was a device with 400,000 pixels, they also have a demonstration of a device with more than a million pixels, and they have not yet found an upper limit.

Two prototype cryocoolers to test superconducting cameras

JPL team members with two prototype cryocoolers that will be used to test the superconducting camera at far ultraviolet wavelengths. From left to right: Emanuel Knehr, Boris Korzh, Jason Allmaras and Andrew Beyer. Credit: Boris Korzh/NASA JPL

One of the most exciting things the researchers think their camera could be useful for is searching for Earth-like planets outside our solar system. To successfully detect these planets, future space telescopes will observe distant stars and look for small bits of reflected or emitted light coming from orbiting planets. Detecting and analyzing these signals is extremely challenging and requires very long exposure times, meaning every photon collected by the telescope is very valuable. A reliable, low-noise camera is critical to detecting these incredibly small amounts of light.

SNSPD cameras can also be used on Earth to detect optical communications signals from deep space missions. In fact, NASA is currently demonstrating this capability through the Deep Space Optical Communications (DSOC) project, the first demonstration of free-space optical communications from interplanetary space. DSOC sends data from a spacecraft called Psyche – which launched on October 13 and is headed for the asteroid Psyche – to an SNSPD-based ground terminal at the Palomar Observatory. Optical links can transmit data at a much higher speed than radio frequency links from interplanetary distances. The excellent timing resolution of the camera developed for the ground station receiving Psyche data allows it to decode optical data from the spacecraft, allowing much more data to be received in a given time than if radio signals were used.

These sensors will also be useful for many applications on Earth. Because the operational wavelength of this camera is very flexible, it can be optimized for biomedical imaging applications to detect weak signals from cells and molecules that were previously undetectable. Dr. McCaughan commented: “We’d love to get these cameras into the hands of neuroscientists. This technology could provide them with a new tool to study our brains, in a completely non-intrusive way.”

Finally, the fast-growing field of quantum technology, which promises to transform the way we secure communications and transactions and the way we simulate and optimize complex processes, will also benefit from this exciting technology. A single photon can be used to transfer or calculate one bit of quantum information. Many companies and governments are currently trying to scale up quantum computers and communications links, and access to a single-photon camera that is so easily scalable could overcome one of the biggest hurdles to unlocking the full potential of quantum technologies.

According to the research team, the next steps will be to perform this initial demonstration and optimize it for space applications. “Right now we have a proof-of-concept demonstration,” says co-project leader Dr. Boris Korzh, “but we will have to optimize it to show its full potential.” The research team is currently planning ultra-efficient camera demonstrations that will validate the usability of this new technology in both ultraviolet and infrared.

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