Quantum computing moves forward

Mar 08, 2013 by Cather­ine Zan­donella
Quantum computing moves forward
A silicon chip levitates individual atoms used in quantum information processing. Credit: Curt Suplee and Emily Edwards, Joint Quantum Institute and University of Maryland. Credit: Science

New technologies that exploit quantum behavior for computing and other applications are closer than ever to being realized due to recent advances, according to a review article published this week in the journal Science.

These advances could enable the creation of immensely powerful computers as well as other applications, such as highly sensitive detectors capable of probing biological systems. "We are really excited about the possibilities of new and new experimental systems that have become available in the last decade," said Jason Petta, one of the authors of the report and an associate professor of physics at Princeton University.

Petta co-authored the article with David Awschalom of the University of Chicago, Lee Basset of the University of California-Santa Barbara, Andrew Dzurak of the University of and Evelyn Hu of Harvard University.

Two significant breakthroughs are enabling this forward progress, Petta said in an interview. The first is the ability to control quantum units of information, known as quantum bits, at room temperature. Until recently, tempera tures near absolute zero were required, but new diamond-based materials allow spin qubits to be operated on a table top, at room temperature. Diamond-based sensors could be used to image single molecules, as demonstrated earlier this year by Awschalom and researchers at Stanford University and IBM Research (Science, 2013).

The second big development is the ability to control these quantum bits, or qubits, for several seconds before they lapse into classical behavior, a feat achieved by Dzurak's team (Nature, 2010) as well as Princeton researchers led by Stephen Lyon, professor of electrical engineering (Nature Materials, 2012).

The development of highly pure forms of silicon, the same material used in today's , has enabled researchers to control a quantum known as "spin". At Princeton, Lyon and his team demonstrated the control of spin in billions of electrons, a state known as coherence, for several seconds by using highly pure silicon-28.

Quantum-based technologies exploit the physical rules that govern very small particles—such as atoms and electrons—rather than the classical physics evident in everyday life. New technologies based on "spintron ics" rather than electron charge, as is currently used, would be much more powerful than current technologies.

In quantum-based systems, the direction of the spin (either up or down) serves as the basic unit of information, which is analogous to the 0 or 1 bit in a classical computing system. Unlike our classical world, an electron spin can assume both a 0 and 1 at the same time, a feat called entanglement, which greatly enhances the ability to do computations.

A remaining challenge is to find ways to transmit quantum information over long distances. Petta is exploring how to do this with collaborator Andrew Houck, associate professor of electrical engineering at Princeton. Last fall in the journal Nature, the team published a study demonstrating the coupling of a spin qubit to a particle of light, known as a photon, which acts as a shuttle for the quantum information.

Yet another remaining hurdle is to scale up the number of qubits from a handful to hundreds, according to the researchers. Single have been made using a variety of materials, including electronic and nuclear spins, as well as superconductors.

Some of the most exciting applications are in new sensing and imaging technologies rather than in comput ing, said Petta. "Most people agree that building a real quantum computer that can factor large numbers is still a long ways out," he said. "However, there has been a change in the way we think about quantum mechanics – now we are thinking about quantum-enabled technologies, such as using a spin qubit as a sensitive magnetic field detector to probe biological systems."

Explore further: 'Cavity protection effect' helps to conserve quantum information

More information: Awschalom, David D., Bassett, Lee C. Dzurak, Andrew S., Hu, Evelyn L., and Petta, Jason R. 2013. Quantum Spintronics: Engineering and Manipulating Atom-Like Spins in Semiconductors. Science. Vol. 339 no. 6124 pp. 1174–1179. DOI: 10.1126/science.1231

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5 / 5 (1) Mar 08, 2013
... yes, yes, yes, but when can we have it?
1 / 5 (2) Mar 08, 2013
One is the Quanta.

Forget the computer for a moment.

We might perceive of the spinning donut, where spin up or spin down is determined by whether energy flow is into the top of the hole and out through the bottom, or into the bottom hole and out through the top, orientation being determined by a gravity source. That being the case then, forcing state changes of the toroidal field to which is derived the property of spin must constitute a manipulation of the frame of reference, determined to be the gravity. There you have it - Gravity Drive.
1 / 5 (5) Mar 08, 2013
"However, there has been a change in the way we think about quantum mechanics"

Of course. The physicists who always told me that QM never operates at room temperatures, due to insurmountable thermodynamics, finally retired or died off. You can thank them for holding back physics by two decades. There are no different than the propeller heads who advocated new nuclear reactors in cities or geologists who parrot whatever the oil boss requests
1.3 / 5 (4) Mar 09, 2013
Quantum mechanics might not be confusing at all.

If you split the entire universe into the physical universe (positive energy) and infinite separate mental parallel universes (negative energy), the wave collapse might be explainable as where all the universes meet in the quantum field. Matter and antimatter is created in this wave collapse, and that gives us the reality we observe. Se more at www.crestroy.com
1 / 5 (6) Mar 09, 2013
yes, yes, yes, but when can we have it
IMO the computational power of quantum computers can never beat the classical ones at the moment, when the computational power of classical computers (i.e. the product of precision and speed) is already limited with uncertainty principle. This theorem was already demonstrated for the throughput of quantum communication and IMO it applies to the processing speed of quantum computers as well.

So, when the increased effort into development of quantum computers will not bring any significant practical advantage, then the free market economy will simply never adopt it, because it would have no significant reason for doing it. But because the physicists do need some jobs and salary, their lobby will force such a research due the inertia of research.
2.7 / 5 (7) Mar 09, 2013
@ValeriaT Not sure if trolling, or just stupid.
1 / 5 (3) Mar 09, 2013
It's quite easy to understand: the existing quantum computers are very fast, but their precision is very low (few qbits). To achieve the same computational speed of classical computers the calculations must be repeated multiple-times, which would wipe out the advantage of processing speed. This is because the Heisenberg uncertainty principle limits the speed of information processing with product of speed and precision (phase conjugated variables). The physical laws are valid for everyone.
not rated yet Mar 10, 2013
"an electron spin can assume both a 0 and 1 at the same time, a feat called entanglement,"

That should read superposition, not entanglement.