MadSci Network: Computer Science

Re: How fast will conventional desktop computers eventually go?

Date: Wed Jun 13 15:57:35 2001
Posted By: Michael McDonald, Staff, V.P./Exe. Director NanoComputer Dream Team, NanoComputer Dream Team
Area of science: Computer Science
ID: 987959368.Cs

Hi Chris,
I really feel like we will start seeing operations in the teraflops before 
the turn of the century. Here is something that might help in what is 
ahead for us.

New Light-Based Computer Runs At Quantum Speeds 

A simple computer that marries the mind-boggling computing power of 
quantum mechanics with the ease of manipulating light has been built by 
researchers at the University of Rochester. The device proves that a 
specific quirk of atoms, which lets scientists conduct huge computations 
almost instantly, can be perfectly mimicked by light, which is much more 
practical to control than individual atoms. 
The result could be a computer that performs some tasks a billion times 
faster than today’s supercomputers, using relatively simple technology 
that’s already well understood. The research behind the device was 
revealed at the Lasers and Electro-Optics Quantum Electronics and Laser 
Science Conference in Baltimore, Md. 

The device mimics quantum interference, an important property that makes 
quantum computers exponentially faster at tasks such as breaking 
encryption codes or searching huge databases. Instead of interference, 
conventional computers use particles called electrons to perform tasks 
sequentially, like a librarian looking for a book by inspecting the entire 
library one volume at a time. Interference essentially allows you to make 
clones of that librarian—one librarian for every book—and set them all 
loose at once. The new device proves that using light interference is just 
as effective as quantum interference in retrieving items from a database. 

"There’s a big push to explore information processing based on quantum 
mechanics," says Ian Walmsley, professor of optics at the University of 
Rochester, who lead the team that invented the device. "You can do things 
with quantum mechanics that are impossible on classical machines. What 
we’ve shown here is that if you have a quantum computer that is based 
entirely on quantum interference, we can build you a computer that is 
equally efficient, based entirely on light interference. And light is a 
whole lot easier to manipulate than quantum systems." 

One of the biggest limitations of quantum computers had always been 
thought to be their need for entanglement—a condition where different 
particles become linked, sharing many similar properties like the 
librarian clones sharing similarities with each other. Entanglement is 
difficult to achieve, and so far it has not been done for more than a few 
particles at a time. Scientists then found that entanglement may not be 
necessary for operations such as database searches if quantum interference 
were used. When Walmsley heard this, he was sure he could build a computer 
that used light interference instead of subatomic particle interference. 

"We wanted to show that the implementations which have been done with 
quantum computing have an exact analogy that is just as effective in light-
based processes," says Walmsley. 

Walmsley’s device uses a piece of transparent tellurium dioxide called an 
acousto-optic modulator. This acts as the database by storing the 
information in the form of acoustic waves. A transducer vibrates against 
one side of the modulator, sending waves through it much like a stereo 
speaker would send sound waves through the air. The waves slightly 
compress some parts of the modulator and slightly expand others, creating 
a pattern in which the database information resides. 

To search the database, Walmsley directs a beam of light toward the 
modulator. The light is first split into two, with one part traveling 
through a prism so that a rainbow of different frequencies of light shines 
on the modulator. Each frequency shines through a different compressed or 
expanded part of the tellurium dioxide, which bends that frequency of 
light the way a straw appears bent when sticking out of a glass of water. 
The rainbow of frequencies is then recombined into a single beam. By 
mixing the new beam with the original beam that entered the device, a 
single frequency will emerge as having been altered by its trip through 
the database. 

So in the case of Walmsley’s device, 50 different frequencies of light 
shine through the modulator, and if the 20th frequency is the altered one, 
then Walmsley knows that the bit of information he was searching for is 
located at position 20 in the database. A conventional computer would have 
had to check 20 times to find the location. If the database in question 
were the Manhattan phone book, the search for a single phone number could 
take a conventional computer several million searches, while a light-based 
device could pinpoint the number in just one. 

What makes the device particularly attractive is that it is so simple in 
comparison to quantum computers. Engineers have had decades of experience 
precisely manipulating light and all the concepts in the device are based 
on well-known, 19th-century classical physics—though as Walmsley points 
out, the technology to carry out the experiment only became available in 
the last 10 years. "In effect, we are leveraging new physics on the back 
of optical technology; a synergy that is particularly easy at Rochester, 
and illustrates the close links between basic science and engineering." 

The research was funded by Department of Defense through the Center for 
Quantum Information. Other researchers involved in the work were: graduate 
student Pablo Londero and postdoctoral students Christophe Dorrer, Sascha 
Wallentowitz, and Konrad Banaszek. 


Note: This story has been adapted from a news release issued by University 
Of Rochester for journalists and other members of the public. If you wish 
to quote from any part of this story, please credit University Of 
Rochester as the original source. You may also wish to include the 
following link in any citation:

Current Queue | Current Queue for Computer Science | Computer Science archives

Try the links in the MadSci Library for more information on Computer Science.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2001. All rights reserved.