The National Institute of Standards and Technology (NIST) and its research partners have achieved a groundbreaking feat in the field of imaging technology. They have successfully developed a superconducting camera that contains a remarkable 400,000 pixels, a staggering 400 times more than any other existing device of its kind. This innovative creation has the potential to transform various scientific disciplines, enabling scientists to capture extremely faint light signals from distant celestial objects and even within the complex structures of the human brain. The remarkable increase in pixel count will unlock countless new possibilities in the realms of science and biomedical research. The breakthrough was reported by the researchers in the esteemed scientific journal Nature on October 26.
The NIST camera consists of arrays of ultrathin electrical wires that become superconducting when cooled to extremely low temperatures. This cooling process is essential, as it ensures that electric current moves without any resistance until it is interrupted by a photon strike at a specific location or pixel on the grid. This disruption in superconductivity at the pixel level allows for the detection of the energy imparted by even a single photon. By combining the locations and intensities of all the photons, a complete image can be formed. Although the concept of superconducting cameras capable of detecting single photons was developed over two decades ago, these early devices were severely limited, containing only a few thousand pixels, rendering them unsuitable for most practical applications.
Challenges in Expanding Pixel Count
The primary challenge in expanding the number of pixels in a superconducting camera lies in the difficulty of individually connecting every chilled pixel to its own readout wire. Each component of the camera must be cooled to ultralow temperatures to function correctly. Connecting millions of pixels to the cooling system on an individual basis is virtually impossible. To overcome this limitation, NIST researchers Adam McCaughan and Bakhrom Oripov partnered with scientists from NASA’s Jet Propulsion Laboratory in Pasadena, California, and the University of Colorado Boulder. Together, they devised an ingenious solution: the signals from multiple pixels were combined onto just a few room-temperature readout wires.
The researchers took advantage of a fundamental characteristic of superconducting wires that allows current to flow freely up to a certain maximum “critical” current. By applying a current just below this maximum threshold to the sensors, the researchers created conditions wherein a single photon strike at a pixel would destroy superconductivity. As a result, the current, which could previously flow without resistance, is shunted to a small resistive heating element connected to each pixel. This shunted current generates an electrical signal that can be rapidly detected.
To construct the camera, the team utilized intersecting arrays of superconducting nanowires, forming multiple rows and columns similar to a tic-tac-toe board. Each pixel, defined by the point where vertical and horizontal nanowires intersect, is uniquely situated within its corresponding row and column. This arrangement enabled the researchers to measure signals from an entire row or column of pixels, significantly reducing the number of readout wires required. By placing a superconducting readout wire parallel to but not touching the rows and another wire parallel to but not touching the columns, the team could accurately locate the pixel based on the difference in arrival time of voltage pulses generated when a photon strike created a hotspot in the readout wire.
Paving the Way for Future Applications
The successful implementation of this new readout architecture by Oripov led to a substantial increase in the number of pixels in the superconducting camera. In a matter of weeks, the pixel count skyrocketed from 20,000 to an astounding 400,000. Furthermore, the scalability of the readout technology offers immense potential for even larger cameras in the future. McCaughan envisions the possibility of creating a superconducting single-photon camera with tens or even hundreds of millions of pixels, revolutionizing the field of imaging technology.
Moving forward, the NIST research team aims to enhance the sensitivity of the prototype camera, establishing its capability to capture virtually every incoming photon. The camera’s enhanced sensitivity will enable a myriad of low-light applications, including imaging faint galaxies and planets beyond our solar system, measuring light in photon-based quantum computers, and contributing to groundbreaking biomedical studies utilizing near-infrared light to explore the intricate depths of human tissue.
The creation of a superconducting camera with an unprecedented 400,000 pixels marks a major breakthrough in imaging technology. This remarkable accomplishment by the NIST research team, in collaboration with NASA’s Jet Propulsion Laboratory and the University of Colorado Boulder, opens up extraordinary possibilities in scientific and biomedical research. The ability to capture extremely weak light signals from various sources, including celestial objects and the human brain, has the potential to revolutionize our understanding of the world around us. As the researchers continue to refine the technology, we can anticipate the emergence of even more advanced superconducting cameras with millions of pixels, paving the way for countless new discoveries and scientific breakthroughs in the future.