Featured Research

from universities, journals, and other organizations

New Quantum Key System Combines Speed, Distance

Date:
June 11, 2007
Source:
National Institute of Standards and Technology
Summary:
Researchers have built a prototype high-speed quantum key distribution system, based on a new detector system that achieves dramatically lower noise levels than similar systems.

Detection stage of the NIST prototype quantum key distribution system: Photons are "up-converted" from 1310 to 710 nm by one of the two NIST-designed converters at right, then sent to one of two commercial silicon avalanche photo diode units to the left.
Credit: NIST

Researchers at the National Institute of Standards and Technology (NIST) have built a prototype high-speed quantum key distribution (QKD) system, based on a new detector system that achieves dramatically lower noise levels than similar systems. The new system, they say, can perform a theoretically unbreakable "one-time pad" encryption, transmission and decryption of a video signal in real-time over a distance of at least 10 kilometers.

Key distribution--the problem of ensuring that both the sender and receiver of an encrypted message (and no one else) share the same long string of random digits (the so-called "key") used to encode and decode the message--has always been one of the most important challenges in cryptography. Since the 1980's it's been recognized that the unique properties of quantum mechanics--the fact that certain measurements cannot be made without altering the thing measured--offered the possibility of a system that could transmit as long a key as desired between two parties with no chance that it could be copied undetectably by a third party.

Since then the race has been on to build a fast, practical and reliable QKD system. One important requirement for any candidate system is that it be compatible with existing fiber-optic telecom networks that transmit at wavelengths of either 1550 or 1310 nanometers (nm) to reach the greatest distance. Another requirement is a highly efficient photon detector that can detect single photons reliably without introducing significant amounts of "noise." One of the best low-noise detectors, a silicon-based avalanche photo diode (Si-APD), does not function at the telecom wavelengths. Instead, it operates best at much shorter wavelengths around 700 nm. To take advantage of the Si-APD, the NIST group designed a sub-system to "up-convert" single photons from a transmission wavelength of 1310 nm to 710 nm for high-efficiency detection.

Their QKD system that incorporates this up-conversion technique, described in a recent paper,* generates and transmits secure keys at a rate of over half a million bits per second over 10 km of optical fiber, fast enough to encrypt streaming digital video using one-time pad in real time. The group also has transmitted secure keys at rates near 10 kilobits per second at five times that distance. The same team last year set a speed record for transmission of secure keys over a kilometer of fiber. This work improves the distance by at least 10 times.

Advantages of the new system, according to the research team, include high speed, high efficiency, low noise and convenience of operation. The fact that it uses a 1310 nm transmission wavelength somewhat limits the propagation distance but adds the advantage that the parallel "classical-quantum" communication, which is needed for a full QKD system, can be realized in a single fiber without significant interference. Details of NIST's up-conversion QKD research are available at http://w3.antd.nist.gov/quin.shtml.

* H. Xu, L. Ma, A. Mink, B. Hershman and X. Tang. 1310-nm quantum key distribution system with up-conversion pump wavelength at 1550 nm. Optics Express, Vol. 15, Issue 12, pp. 7247-7260.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology. Note: Materials may be edited for content and length.


Cite This Page:

National Institute of Standards and Technology. "New Quantum Key System Combines Speed, Distance." ScienceDaily. ScienceDaily, 11 June 2007. <www.sciencedaily.com/releases/2007/06/070609112919.htm>.
National Institute of Standards and Technology. (2007, June 11). New Quantum Key System Combines Speed, Distance. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2007/06/070609112919.htm
National Institute of Standards and Technology. "New Quantum Key System Combines Speed, Distance." ScienceDaily. www.sciencedaily.com/releases/2007/06/070609112919.htm (accessed October 20, 2014).

Share This



More Matter & Energy News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gulfstream G500, G600 Unveiling

Gulfstream G500, G600 Unveiling

Flying (Oct. 20, 2014) — Watch Gulfstream's public launch of the G500 and G600 at their headquarters in Savannah, Ga., along with a surprise unveiling of the G500, which taxied up under its own power. Video provided by Flying
Powered by NewsLook.com
Japanese Scientists Unveil Floating 3D Projection

Japanese Scientists Unveil Floating 3D Projection

Reuters - Innovations Video Online (Oct. 20, 2014) — Scientists in Tokyo have demonstrated what they say is the world's first 3D projection that floats in mid air. A laser that fires a pulse up to a thousand times a second superheats molecules in the air, creating a spark which can be guided to certain points in the air to shape what the human eye perceives as an image. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) — Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com
What We Know About Microsoft's Rumored Smartwatch

What We Know About Microsoft's Rumored Smartwatch

Newsy (Oct. 20, 2014) — Microsoft will reportedly release a smartwatch that works across different mobile platforms, has a two-day battery life and tracks heart rate. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins