Connecting (quantum) dots: Spin technique moves researchers closer to creating first viable high-speed quantum computer

Feb 26, 2013

Recent research offers a new spin on using nanoscale semiconductor structures to build faster computers and electronics. Literally.

University of Pittsburgh and Delft University of Technology researchers reveal in the Feb. 17 online issue of Nature Nanotechnology a new method that better preserves the units necessary to power lightning-fast electronics, known as qubits (pronounced CUE-bits). Hole spins, rather than electron spins, can keep quantum bits in the same physical state up to 10 times longer than before, the report finds.

"Previously, our group and others have used electron spins, but the problem was that they interacted with spins of nuclei, and therefore it was difficult to preserve the alignment and control of electron spins," said Sergey Frolov, assistant professor in the Department of Physics and Astronomy within Pitt's Kenneth P. Dietrich School of Arts and Sciences, who did the work as a postdoctoral fellow at Delft University of Technology in the Netherlands.

Whereas normal computing bits hold mathematical values of zero or one, quantum bits live in a hazy of both states. It is this quality, said Frolov, which allows them to perform multiple calculations at once, offering exponential speed over . However, maintaining the 's state long enough to perform computation remains a long-standing challenge for .

"To create a viable quantum computer, the demonstration of long-lived , or qubits, is necessary," said Frolov. "With our work, we have gotten one step closer."

The holes within hole spins, Frolov explained, are literally empty spaces left when electrons are taken out. Using extremely thin filaments called InSb (indium antimonide) nanowires, the researchers created a transistor-like device that could transform the electrons into holes. They then precisely placed one hole in a nanoscale box called "a quantum dot" and controlled the spin of that hole using electric fields. This approach— featuring nanoscale size and a higher density of devices on an electronic chip—is far more advantageous than magnetic control, which has been typically employed until now, said Frolov.

"Our research shows that holes, or empty spaces, can make better spin qubits than for future quantum computers."

"Spins are the smallest magnets in our universe. Our vision for a quantum computer is to connect thousands of spins, and now we know how to control a single spin," said Frolov. "In the future, we'd like to scale up this concept to include multiple qubits."

Explore further: Scientists use simple, low cost laser technique to improve properties and functions of nanomaterials

More information: The paper, "Electrical control over single hole spins in nanowire quantum dots," appeared online Feb. 17 in Nature Nanotechnology.

Related Stories

Advancing quantum computing

May 30, 2012

European researchers have made important advances in understanding the major stumbling block to realisation of quantum computers, a phenomenon known as decoherence.

Better control of building blocks for quantum computer

Dec 23, 2010

Dutch scientists from the Kavli Institute of Nanoscience at Delft University of Technology and Eindhoven University of Technology have succeeded in controlling the building blocks of a future super-fast quantum ...

Recommended for you

PPPL studies plasma's role in synthesizing nanoparticles

17 hours ago

DOE's Princeton Plasma Physics Laboratory (PPPL) has received some $4.3 million of DOE Office of Science funding, over three years, to develop an increased understanding of the role of plasma in the synthesis ...

First ab initio method for characterizing hot carriers

Jul 17, 2014

One of the major road blocks to the design and development of new, more efficient solar cells may have been cleared. Researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) have developed ...

User comments : 0