NIST Detector Counts Photons With 99 Percent Efficiency

Using essentially the same technology that permitted them to achieve 88 percent detection efficiency five years ago,** the team has enhanced its ability to detect photons largely by improving the alignment of the detector and the optical fibers that guide photons into it.

The basic principle of the detector is to use a superconductor as an ultra-sensitive thermometer. Each individual photon hitting the detector raises the temperature—and increases electrical resistance—by a minute amount, which the instrument registers as the presence of a photon.

According to team member Sae Woo Nam, the advantage of this type of single photon detector is that the new detector design not only measures lower levels of light than have ever been possible, but does so with great accuracy.

“When these detectors indicate they’ve spotted a photon, they’re trustworthy. They don’t give false positives,” says Nam, a physicist with NIST’s Optoelectronics division. “Other types of detectors have really high gain so they can measure a single photon, but their noise levels are such that occasionally a noise glitch is mistakenly identified as a photon. This causes an error in the measurement. Reducing these errors is really important for those who are doing calculations or communications.”

The ability to count individual photons is valuable to designers of certain types of quantum computers as well as scientists engaged in quantum optical experiments, which concern exotic states of light that cannot be described by classical physics. But one of the most promising potential applications of a high-efficiency photon detector is a way to secure long-distance data transmission against unwanted interception. A detector that could recognize that a photon forming part of a transmission was missing would be a substantial defense against information theft.

The team has optimized the detection for 810 nanometers—an infrared wavelength—and it still has high efficiency at other wavelengths that are interesting for fiber optic communications, as well as the quantum optics community. Ironically, the detector is so efficient that it outstrips current technology’s ability to determine its precise efficiency.

“We can’t be sure from direct measurement that we’ve achieved 99 percent efficiency because the metrology is not in place to determine how close we are—there’s no well-established technique,” Nam says. “What is great about our latest progress is that we measure nearly the same detection efficiency for every device we build, package and test. It’s the reproducibility that gives us confidence.”

The team is currently working to develop evaluation techniques that can measure up to the detector’s abilities, and Nam says the team’s creation could also help evaluate other light-gathering devices.

“NIST offers a standardized service for measuring the efficiency of photodetectors and optical power meters,” he says. “We’re trying to develop a calibration technique that extends to ultra-low levels of light. It should be valuable for anyone looking at single photons.”

* A.E. Lita, B. Calkins, L.A. Pellouchoud, A.J. Miller and S. Nam. Superconducting transition-edge sensors optimized for high-efficiency photon-number resolving detectors. Presented at the SPIE Symposium on SPIE Defense, Security, and Sensing, Orlando World Center Marriott Resort and Convention Center, Crystal J1 Ballroom, 3 p.m. April 7, 2010.

** See “NIST Photon Detectors Have Record Efficiency” in NIST Tech Beat, June 2, 2005, at www.nist.gov/public_affairs/techbeat/tb2005_0602.htm#photon.

Media Contact

Chad Boutin Newswise Science News

More Information:

http://www.nist.gov

All latest news from the category: Physics and Astronomy

This area deals with the fundamental laws and building blocks of nature and how they interact, the properties and the behavior of matter, and research into space and time and their structures.

innovations-report provides in-depth reports and articles on subjects such as astrophysics, laser technologies, nuclear, quantum, particle and solid-state physics, nanotechnologies, planetary research and findings (Mars, Venus) and developments related to the Hubble Telescope.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors