Is quantum Internet search on the way?

In classical computing, random access memory (RAM) is needed to make things “work.” But it is subject to a certain level of energy loss. But what if you could create low-energy quantum access memory (QRAM) that would not only work in terms of quantum computing, but that could also be applied to classical computing?

Seth Lloyd, a researcher at MIT, believes that a new architecture for QRAM could be used to not only reduce the energy wasted by RAM, but also be used for completely anonymous Internet search. “My colleagues and I were interested in protocols for quantum Internet search,” he tells PhysOrg.com. “And we were also interested in what we could do with even a rudimentary quantum Internet. But first you have to develop this quantum RAM.”

Lloyd worked with Vittorio Giovannetti at the NEST-CNR-INFM in Pisa, Italy, and with Lorenzo Maccone at the University of Pavia, in Pavia, Italy, to put together a system that would work as QRAM. They even called researchers and developers at Texas Instruments to see if their idea is feasible. The results of their efforts are published in Physical Review Letters: “Quantum Random Access Memory.”

“Our design is based on a bucket brigade sort of design,” Lloyd says. He explains that the design came about when he and his colleagues were trying to figure out how to make QRAM work based of classical RAM design. “There is just too much decoherence in classical RAM architecture. Too much for the quantum states to remain intact.”

Lloyd explains how classical RAM works: “Lets say you have a gigabyte of RAM. That means you have one billion memory slots, each with an address. When you wan to access one, an address is given, let’s say it is about 30 bits long. The first bit will throw two switches, the next will throw four, and so on until a billion switches are thrown at once.”

“The conventional design is incredibly wasteful. And it is susceptible to noise and interference. We saw that this wasn’t going to work at all in terms of quantum RAM,” Lloyd continues. He and his colleagues set to work on their bucket brigade design.

“It is a sneakier way to access RAM,” he explains. “In the same gigabyte RAM, we send the first bit of the address along a path. Once the first layer is accessed, the next bit comes, following the path of the first bit, until it reaches the second layer. The third bit then traces the two paths before it. In this way, all the bits of the address only interact with two switches.”

There are problems with this set-up, however. Even though the experts at Texas Instruments agree that it would work, they point out that the energy saved using QRAM would not offset the larger energy problems associated with classical computing. Besides, Lloyd admits, the QRAM set-up is a little slower than the RAM. “You’d have to be willing to make that trade-off.”

That brings Lloyd back to the idea of quantum Internet search. “If you had a quantum Internet, then this would be useful,” he points out. “This offers a huge decrease in energy used and an increase in robustness.” The other interesting aspect is the possibility of completely anonymous Internet search. Not even your service provider would know who you are or what you search for.

This all sounds very nice, but is it something that could be implemented in the near future? Lloyd sees the potential, since immediate implementation isn’t possible. “We’re working on setting up an experiment with optics to show how this would work.” But the real issue is setting up an infrastructure that could support a quantum Internet.

“For a quantum Internet to work,” Lloyd explains, “we need what is called dark fiber. In some places, this is already being used for classical communications. But we would need more of it, and the necessary quantum switching structure is only just now being developed.”

If Lloyd is right, the next few years could be very interesting in terms of quantum technology and communications.

Copyright 2007 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

Related stories:

Turning 'funky' quantum mysteries into computing reality
The strange world of quantum mechanics can provide a way to surpass limits in speed, efficiency and accuracy of computing, communications and measurement, according to research by MIT scientist Seth Lloyd.
The key to a more efficient nanolaser?
“There are some discussions about the recent applications on photonic nanolasers and photonic integrated circuits based on photonic crystals,” Toshihiko Baba tells PhysOrg.com in an email. Baba, a scientist at the Yokohama National University in Japan, has been working on improving the efficiency of photonic crystal nanolasers.
Landmark modeling study reveals how ferroelectric computer memory works
A collaboration of University of Pennsylvania chemists and engineers has performed multi-scale modeling of ferroelectric domain walls and provided a new theory of behavior for domain-wall motion, the “sliding wall” that separates ferroelectric domains and makes high-density ferroelectric RAM (FeRAM) possible.
Data Domain Touts 'Industry's Most Scalable' Controller
The DD580 storage controller can deliver as much as 800GB per hour of aggregate deduplication throughput, Data Domain says.
Scientists present method for entangling macroscopic objects
Building upon recent studies on optomechanical entanglement with lasers and mirrors, a group of scientists has developed a theoretical model using entanglement swapping in order to entangle two micromechanical oscillators. This ability could lead to advances in information processing, as well as other applications that use micromechanical resonators, such as electrometers, displacement detectors, and radio frequency signal processors, wrote scientists Stefano Pirandola et al. in a recent Physical Review Letters.
Hitching a Ride Out of a Gluttonous Black Hole
“Ever since Stephen Hawking showed that black holes evaporate,” says Seth Lloyd, an MIT physicist, “people have wondered about the stuff that comes out of them. Is it just garbage, or is it something else?” With his piece published in Physical Review Letters on February 14, Lloyd attempts to show that quantum information does escape black holes, and that this information is useful and can have lasting impacts on how we understand our universe.
Closing In On Quantum Chemistry
Researchers in the Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley have simulated the process by which a quantum computer could calculate to high precision an important basic property of two small molecules. Simulated quantum calculations of the ground-state energies of water (H₂O) and lithium hydride (LiH) are the first of this kind ever done for specific molecules.
Xilinx delivers world's most advanced 90nm FPGAs to key customers
SAN JOSE, Calif., June 28, 2004 - Xilinx, Inc., the world's leading supplier of programmable logic solutions and inventor of the FPGA, announced today that it has initiated shipment of Virtex-4 FPGAs to its early access customers. Manufactured using the world's first triple-oxide 90nm CMOS technology with 11-layer metal interconnect, Virtex-4 devices represent a quantum leap in programmable device architecture, technology, and system design capabilities. With over $2.5B in cumulative revenue, Virtex FPGAs are the world's most popular programmable logic brand.

News discussion:

Physics news