FEATURE SINGLE PHOTON DETECTION
Photon counting advances push the boundaries of quantum innovation
Susan Fourtané explores developments in single-photon detection that are advancing a range of quantum applications
S
ince the first direct detection of light at the single-photon level was achieved in the 1930s,
single-photon detection has become essential to enabling a range of modern technologies, including quantum networks and communications, quantum computation protocols and imaging, quantum cryptography protocols, time-of-flight lidar, and dark matter detection. Here, we explore some of the
latest advancements taking place in the field of single- photon detection, from Nasa’s groundbreaking PEACOQ system to innovations presented at the recent Photonics West.
High-speed quantum communication Back in January 2023, researchers at Nasa’s Jet Propulsion Laboratory (JPL) described and demonstrated in Optica a new detector for measuring the arrival times of photons. Named PEACOQ (performance-enhanced array for counting optical quanta), the detector was designed
as part of a Nasa programme enabling new technologies for space-to-ground quantum communication. According to the team, at the time of publishing, no other detector could match PEACOQ’s single-photon counting speed and timing resolution. The work could help establish long-range quantum computer communication networks. “The PEACOQ detector can count a billion events per second while maintaining time resolution (the accuracy of timing when a single photon arrives at the detector) below 100 picoseconds,” said Matthew Shaw, leader of the research and Group Supervisor for Superconducting and Quantum Devices at JPL. In quantum communication, computers encode information as quantum bits (qubits) in electrons and photons, which can’t be copied and retransmitted without being destroyed. While this makes it a very secure method of communication, transmitting quantum information through optical fibres can be challenging, as the encoded photons degrade after just a few dozen miles, greatly limiting the size of any future networks. To overcome these
Nasa’s PEACOQ detector is made of 32 niobium nitride superconducting nanowires on a silicon chip, which enables high count rates with high precision
26 Electro Optics March 2024
limitations, scientists are looking to build dedicated free-space optical quantum networks, nodes of which will include satellites orbiting Earth. These nodes would relay data by generating pairs of entangled photons that
NIST’s new superconducting camera will have the capability to capture astronomical images under extremely low light conditions
would be sent to two quantum computer terminals hundreds or even thousands of miles apart from each other on the ground. However, for these entangled photons to be received on the ground by a quantum computer’s terminal, a highly sensitive detector such as PEACOQ is needed to precisely measure the time it receives each photon and deliver the data it contains. The detector is designed to
address the challenges of high- speed quantum communication transmission by enabling communication using a state- of-the-art clock frequency of
10GHz. “This allows you to run your communication protocol more times per second, which can either lead to higher data rates in short links, or more distance for long ones,” explains Shaw. As per its present and
future performance, Shaw says that “the PEACOQ detector has achieved efficient, high-rate counting of single infrared photons with high timing accuracy. It has 32 superconducting niobium nitride (NbN) nanowire sensor elements integrated into a single array. In the future, it can be made more efficient
www.electrooptics.com
Ryan Lannom, JPL-Caltech/NASA
S. Kelley/NIST
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