The enormous amounts of quantum data exchanged by quantum computers thousands of kilometers away can be manipulated by a new detector created by JPL and Caltech. The potential to run millions of times faster than current computers lies in quantum computing. However, in order for quantum computers to be connected over long distances, a special quantum communication network will be needed.
To help build such a web, scientists at NASA's Jet Propulsion Laboratory and Caltech have created a device that can count countless tiny photons (particles of quantum light) with incredible accuracy. The Performance-Enhanced Array for Counting Optical Quanta (PEACOQ) detector can monitor the time each photon hits itself in 100 trillionths of a second, at a rate of 1,5 billion photons per second; it's like measuring individual drops of water sprayed from a fire hose. Other detectors could not reach this speed.
"The transmission of quantum information over long distances has been very limited until now," said Ioana Craiciu of the PEACOQ project team, postdoctoral researcher at JPL and first author of the study. "Transmitting quantum information at higher speeds and farther is possible thanks to new detector technologies like the PEACOQ that can measure single photons with a fraction of a millisecond precision."
Traditional computers copy information as a series of 1s and 0s, commonly known as bits, and send it via modems and communication networks. The bits are then transferred over cables, optical fibers, and space using radio waves or flashes of light. After the pieces are retrieved, they are reassembled to produce the original data.
Communication between quantum computers is different. Quantum bits or qubits are used to store information, which are fundamental particles such as electrons and photons that cannot be reproduced and retransmitted without being destroyed. Quantum information is distorted after only a few dozen miles transmitted over optical fibers using encoded photons, increasing the difficulty and greatly reducing the potential size of any future network.
A special free-space optical quantum network could include space "nodes" on Earth-orbiting satellites to enable quantum computers to communicate outside of these constraints. These nodes will act as data transmitters by generating entangled pairs of photons and sending them to two quantum computer terminals hundreds or perhaps thousands of kilometers apart.
Even with a large distance between them, entangled photon pairs are so interconnected that measuring one instantly changes the results of measuring the other. However, a very sensitive detector like the PEACOQ would need to measure exactly when it received each photon and transmit the data it contained so that these entangled photons could be received by the terminal of a quantum computer.
The detector is a small device. It features 32 niobium nitride superconducting nanowires on a silicon chip, with radiating connectors that give the detector its name. The detector is only 13 microns wide. Each nanowire is 10.000 times thinner than a human hair.
Developed by JPL's Micro Devices Laboratory and supported by NASA's Space Communications and Navigation (SCaN) program, the PEACOQ detector must be kept at a cryogenic temperature that is just 272 degrees Fahrenheit below absolute zero (minus 458 degrees Celsius). This preserves the superconducting state of the nanowires; this is necessary for them to convert the absorbed photons into electrical pulses that transmit quantum data.
The detector must be sensitive enough to detect single photons, but must also be built to withstand being bombarded by several photons at once. This dead time is kept to a minimum, although each superconducting nanowire in the detector temporarily loses its ability to detect more photons when struck by a photon. PEACOQ also has 32 nanowires, so when one "dies" the others can fill the void.
According to Craiciu, PEACOQ will soon be used in laboratory experiments to demonstrate quantum communication at faster rates or over longer distances. In the long run, it could offer a solution to the problem of how to send quantum data around the world.
Deep Space Testing
PEACOQ is based on the detector created for NASA's Deep Space Optical Communications (DSOC) technology demonstration and is part of a larger NASA initiative to enable free space optical communications between space and earth. DSOC will launch for the first time later this year alongside NASA's Psyche mission to demonstrate how future high-bandwidth optical communications between Earth and deep space could work.
While the DSOC ground terminal at Caltech's Palomar Observatory in Southern California won't transmit quantum information, it still needs the same high precision to count individual photons coming from the laser from the DSOC transceiver as it travels through deep space.
Matt Shaw, who is responsible for JPL's work on superconducting detectors, said, “This is considered the same technology as a different detector category. "Whether it's coded with quantum information or we want to detect single photons from a laser source in space, we're still counting single photons," he said.
Günceleme: 03/03/2023 18:57