Dr. Dobb's Journal October 1999
Researchers at the Massachusetts Institute of Technology claim to be the first to successfully program a prototype quantum computer to perform quantum simulation. A team led by MIT's David Cory and the Los Alamos National Lab's Raymond Laflamme has developed a general scheme for quantum simulation that works on any quantum computer.
Quantum computers are based on principles of quantum mechanics, which describe the physical state of subatomic particles. The potential advantage of a computer based on quantum mechanics is that more than the binary on/off state can be represented by a single "quantum bit." A quantum bit, called a "qubit," represents the spin or angular momentum of a subatomic particle. The spin can be represented as up or down or up and down simultaneously. Because of this third simultaneous up and down state, also called a "superposition state," far more information can theoretically be represented by a sequence of qubits than by the equivalent number of bits of the binary system.
The MIT prototype involves applying nuclear magnetic resonance to a compound in a test tube and observing the magnetic alignment of the protons. As Cory puts it, "the answer comes back as a burst of energy, which can be converted to useful data using Fourier transforms." After data is stored in this manner, the computer also must incorporate logical gate operations, or commands, to perform calculations.
The MIT prototype can only count to 4, but the seeds have been planted for a potentially major breakthrough in computing. For more information, see "Quantum Simulations on a Quantum Computer" (Physical Review Letters, June 28, 1999, http://www.aps.org/).
Nick Baran
The Secure Digital Music Initiative (SDMI), a music industry consortium, has published its first specification for distributing digitally recorded music via the Internet and other electronic media. The specification, supported by companies and organizations in the music, consumer electronics, and information technology industries, is aimed at protecting the copyrights of musicians and music vendors, while providing convenient accessibility to consumers. The SDMI standard will appear in two phases. Phase one, represented by this first specification, establishes a format for distributing music electronically; phase two will include a screening technology for blocking or filtering out pirated music.
The SDMI covers not only the Internet but portable devices such as CD players and other recording devices that attach to computers. The SDMI governing organization calls devices adhering to the standard "Licensed Compliant Modules" (LCMs). According to the SDMI, "the specification also describes requirements for secure, authenticated communications between applications and LCMs and between LCMs and portable devices."
SDMI is the music industry's response to the threat of the MP3 digital music transport protocol, which is gaining popularity on the Internet. MP3 lets users download high-quality digital recordings from the Internet, often in violation of copyrights. Because MP3 employs data compression, its audio quality is not as good as that of a CD recording, but close enough that the difference is indistinguishable.
The question is whether SDMI can successfully stop the growing popularity of MP3. For example, the Grateful Dead, long known for encouraging fans to tape live shows, has embraced MP3 and announced that all its live, fan-recorded music will be freely distributed on the Web. According to John Perry Barlow, a former lyricist for the Grateful Dead, the band hopes to facilitate an opportunity for fans to remix their concert recordings. Other musicians jumping on the MP3 bandwagon include The Beastie Boys, Public Enemy, and Jane's Addiction.
The real test of the SDMI will come when phase two is released and consumers are required to pay for downloaded music. For more information, see http://www.sdmi.org/.
Nick Baran and Amy Lincicum
A study by NEC Research Institute researchers indicates that Internet search engines aren't keeping up with the volume of web pages available on the Internet. The study, conducted by Steve Lawrence and C. Lee Giles, found that the leading search engines (such as Altavista and Lycos) cover only about one sixth of the total pages on the Internetand it takes on average about six months for new pages to appear in their databases. Of course, the volume of web pages keeps increasing at an astronomical rate, rapidly approaching 1 billion pages, so that the fraction of indexed pages is likely to get smaller and smaller.
According to Lawrence, search engines identify new pages to index primarily based on the number of links to the page. This method greatly favors well-known web pages and the links to those pages. Lawrence thinks this favoritism will become a significant problem as the Internet becomes a dominant marketplace. Whether or not a company is indexed on search engines "can have a significant effect on the viability of the company," says Lawrence. "If a company is not listed, it will be very hard [for it] to succeed." For more information on the study, see http://www.wwwmetrics .com/ or http://www.neci.nj.nec.com/ homepages/lawrence/.
Nick Baran
The Object Management Group (OMG) has voted to adopt the Real-Time CORBA 1.0 specification. In a nutshell, the specification consists of a set of extensions to the CORBA spec that enable Object Request Brokers (ORB) to be used as components of real-time systems. In doing so, the OMG admits that some of the general-purpose nature of CORBA has been sacrificed to support real-time demands. On the upside, the OMG adds that the spec is sufficiently general to address both hard and soft real-time issues. Real-time CORBA does not currently address dynamic scheduling, however.
Companies supporting the 1.0 spec include Lucent, Alcatel Alsthom Recherche, Hewlett-Packard, Highlander Communications, IONA, Inprise, Lockheed Martin, Nortel, Object-Oriented Concepts, Objective Interface Systems, Sun, and Tri-Pacific Software. Copies of the specification are available at ftp://ftp.omg.org/pub/ docs/ptc/99-06-02.pdf.
Jonathan Erickson