It's all in the spin: Quantum physics cools down computers

September 25, 2007

The future of Moore's famous law—that the number of transistors squeezed onto a computer chip can be doubled about every two years—is widely seen as threatened by the damaging heat generated by the chips themselves as their transistors become more densely packed.

But a new theory of circuit design from Stanford researchers, recently confirmed by experiments in Germany, exploits the celebrated quirkiness of quantum physics to drastically reduce the heat produced by electricity coursing through the tiny veins of semiconductors.

Stanford physics Professor Shoucheng Zhang says a new generation of semiconductors, designed around the phenomenon known as the Quantum Spin Hall Effect, could keep Moore's law in force for decades to come.

Beyond semiconductors, the theoretical aspect of the effect is intriguing on its own, Zhang said. He and a team at the University of Würzburg published their results Friday, Sept. 21, in Science Express, an online version of Science magazine.

Using special semiconductor material made from layers of mercury telluride and cadmium telluride, the experimenters employed quantum tricks to align the spin of electrons like a parade of tops spinning together. Under these extraordinary conditions, the current flows only along the edges of the sheet of semiconductor.

Interestingly, electrons with identical spins travel in the same direction together, while electrons with the opposite spin move in the opposite direction. Unlike existing semiconductors, this unusual electric current does not generate destructive heat through dissipation of power or the collision of electrons with impurities in the semiconducting material.

The electrons' strange behavior constitutes a new state of matter, Zhang said, joining the three states familiar to high school science students—solids, liquids, gases—as well as more unworldly states such as superconductors, where electrons flow with no resistance. He describes the quest for new states of matter as the holy grail of condensed matter physics.

Similar effects have been demonstrated before, but only at extremely cold temperatures and under the effects of powerful magnetic fields—conditions that cannot exist inside the common computer. "What we managed to do is basically get rid of the magnetic field," Zhang said.

There are other candidates for the next generation of computer chips, including nanotube technology. But Zhang believes that Quantum Spin Hall Effect chips might have the advantage because they can be made from materials already familiar to chip makers. In the long run, so-called "spintronics" could see the spin of electrons becoming more important than their electrical charge: Semiconductors would operate on the basis of spin alone, without electrons moving in their usual form of electrical current.

Zhang's theoretical work was aided by graduate student Taylor Hughes and former graduate student Andrei Bernevig. The U.S. Department of Energy and National Science Foundation funded their work.

Source: Stanford University

Explore further: Uncovering the secrets of super solar power perovskites

Related Stories

Uncovering the secrets of super solar power perovskites

March 16, 2015

The best hope for cheap, super-efficient solar power is a remarkable family of crystalline materials called hybrid perovskites. In just five years of development, hybrid perovskite solar cells have attained power conversion ...

Quantum sensor's advantages survive entanglement breakdown

March 9, 2015

The extraordinary promise of quantum information processing—solving problems that classical computers can't, perfectly secure communication—depends on a phenomenon called "entanglement," in which the physical states of ...

Scientists cook up new electronic material

January 10, 2014

(Phys.org) —Scientists from SLAC, Stanford and Berkeley Lab grew sheets of an exotic material in a single atomic layer and measured its electronic structure for the first time. They discovered it's a natural fit for making ...

Recommended for you

Quantum matter stuck in unrest

July 31, 2015

Using ultracold atoms trapped in light crystals, scientists from the MPQ, LMU, and the Weizmann Institute observe a novel state of matter that never thermalizes.

New blow for 'supersymmetry' physics theory

July 27, 2015

In a new blow for the futuristic "supersymmetry" theory of the universe's basic anatomy, experts reported fresh evidence Monday of subatomic activity consistent with the mainstream Standard Model of particle physics.

Rogue wave theory to save ships

July 29, 2015

Physicists have found an explanation for rogue waves in the ocean and hope their theory will lead to devices to warn ships and save lives.

Researchers build bacteria's photosynthetic engine

July 29, 2015

Nearly all life on Earth depends on photosynthesis, the conversion of light energy into chemical energy. Oxygen-producing plants and cyanobacteria perfected this process 2.7 billion years ago. But the first photosynthetic ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

Nerdle
not rated yet Jun 16, 2009
Wow.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.