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 VOLUME 22-NUMBER 7                                                                     Search :     Thursday, November 20, 2008                                                                        JULY, 2007




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Quantum Key System Combines Speed & Distance
Gaithersburg, MD — 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 1980s, it has 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 1310nm to 710nm for high-efficiency detection.

The QKD system that incorporates this up-conversion technique, described in a recent paper, (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) generates and transmits secure keys at a rate of over half a million bits per second over 10km 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 1310nm 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.


For details, see:
http://w3.antd.nist.gov/quin.shtml


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By Al Lewis, Director of Applications Engineering,
Asymtek, Carlsbad, CA
Fluid dispensing and coating processes are required for many assembly and packaging operations. These processes provide combinations of electrical, mechanical, and thermal properties to components and assemblies for functionality or enhanced reliability. Common processes are surface mount component bonding for assembly, encapsulation and underfill for reliability,
By Tom Adams, teadams@earthlink.net
The idea of putting components inside the printed wiring board instead of on the surface of the board has been around for at least 30 years, although it has been limited to passive components such as the thin film resistive material made by Ohmega Technologies, and more recently the resistor/capacitor laminate core made by Ohmega and Oak/Mitsui. The endless drive toward smaller systems, however, means that attention is being given to placing active components inside the board as well.
 Eastek International: Integrated Global Svcs.
By Bob Wiegand, Vice President, Eastek Int'l, Buffalo Grove, IL
For many entrepreneurs, identifying a U.S.-based contract manufacturer that offers a "one-stop shop" solution can help transform an important new product idea into reality. But how to find a CM partner that offers an accommodating yet disciplined process, with sound leadership and support throughout all phases of design and production?
 Datron: Hi-Speed CNC with     Micro Tool Machining
Milford, NH — New from Datron is its excelsior® Lite CNC machining center. The system, for parts that are 1/4-in. or smaller in size, has been designed specifically for manufacturers who need innovative high-speed technology on a budget.

The excelsior Lite has an aluminum bed rather than the granite table found on its big brother the excelsior EX. While this does impact rigidity to some extent,
 Samtec Expands Signal    Integrity Product Line
New Albany, IN — Samtec has expanded its signal integrity interconnect product line, increasing the ability to provide "Signal Integrity at any Distance" The company has introduced new interconnects and signal integrity services for panel and I/O, cable assemblies and board-to-board applications, as well as expanded signal integrity design resources including Final Inch® PC board design tools.

Asymtek: New Inline Flux Dispensing System
Carlsbad, CA — Asymtek, a Nordson company, is unveiling its new Axiom X-1030 Series dispensing system, designed for selective jetting of traditional flux, no-clean solder fluxes and other precise coating applications.

Available in single or dual lane configurations, the closed-loop X-1030 dispensing system optimizes underfill and package reliability--improving production throughput and equipment utilization by as much as 60-85 percent with the X-1032's dual lane multitasking capabilities.

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