NASA’s Quantum Detector Achieves World-Leading Milestone

Jet Propulsion Laboratory

California Institute of Technology

March 2, 2023

This close-up photograph shows an exquisitely sensitive single Performance-Enhanced Array for Counting Optical Quanta (PEACOQ) detector, which is being developed at JPL to detect single photons – quantum particles of light – at an extremely high rate. Credit: NASA/JPL-Caltech

A new JPL- and Caltech-developed detector could transform how quantum computers, located thousands of miles apart, exchange huge quantities of quantum data.

Quantum computers hold the promise of operating millions of times faster than conventional computers. But to communicate over long distances, quantum computers will need a dedicated quantum communications network.

To help form such a network, a device has been developed by scientists at NASA’s Jet Propulsion Laboratory and Caltech that can count huge numbers of single photons – quantum particles of light – with incredible precision. Like measuring individual droplets of water while being sprayed by a firehose, the Performance-Enhanced Array for Counting Optical Quanta (PEACOQ) detector is able to measure the precise time each photon hits it, within 100 trillionths of a second, at a rate of 1.5 billion photons per second. No other detector has achieved that rate.

“Transmitting quantum information over long distances has, so far, been very limited,” said PEACOQ project team member Ioana Craiciu, a postdoctoral scholar at JPL and the lead author of a study describing these results. “A new detector technology like the PEACOQ that can measure single photons with a precision of a fraction of a nanosecond enables sending quantum information at higher rates, farther.”

Ioana Craiciu, who led the study, stands next to the cryostat that was used to test PEACOQ at temperatures as low as a degree above absolute zero. At this temperature, the detector is in a superconducting state, allowing its nanowires to turn absorbed photons into electrical pulses.
Credit: NASA/JPL-Caltech

Conventional computers transmit data through modems and telecommunication networks by making copies of the information as a series of 1s and 0s, also called bits. The bits are then transmitted through cables, along optical fibers, and through space via flashes of light or pulses of radio waves. When received, the bits are reassembled to re-create the data that was originally transmitted.

Quantum computers communicate differently. They encode information as quantum bits – or qubits – in fundamental particles, such as electrons and photons, that can’t be copied and retransmitted without being destroyed. Adding to the complexity, quantum information transmitted through optical fibers via encoded photons degrades after just a few dozen miles, greatly limiting the size of any future network.

For quantum computers to communicate beyond these limitations, a dedicated free-space optical quantum network could include space “nodes” aboard satellites orbiting Earth. Those nodes would relay data by generating pairs of entangled photons that would be sent to two quantum computer terminals hundreds or even thousands of miles apart from each other on the ground.

Pairs of entangled photons are so intimately connected that measuring one immediately affects the results of measuring the other, even when they are separated by a large distance. But for these entangled photons to be received on the ground by a quantum computer’s terminal, a highly sensitive detector like PEACOQ is needed to precisely measure the time it receives each photon and deliver the data it contains.

The detector itself is tiny. Measuring only 13 microns across, it is composed of 32 niobium nitride superconducting nanowires on a silicon chip with connectors that fan out like the plumage of the detector’s namesake. Each nanowire is 10,000 times thinner than a human hair.


I guess I'm surprised and excited about three bits of information from this article. First of all is the speed utilised in this detector: the Performance-Enhanced Array for Counting Optical Quanta (PEACOQ) detector is able to measure the precise time each photon hits it, within 100 trillionths of a second, at a rate of 1.5 billion photons per second. Whoa. Then we have the incredibly incredibly small size of the detector involved - 13 microns, or 0.00051181102362205 inches, across with 32 niobium nitride superconducting nano wires which are 1/10,000th the width of a human hair. Lastly the future might feature a dedicated free-space optical quantum network including space “nodes” aboard satellites orbiting Earth for transmitting and receiving quantum computer information.


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