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

February 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: Better control of building blocks for quantum computer

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

Related Stories

Better control of building blocks for quantum computer

December 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 computer. ...

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.

Recommended for you

For 2-D boron, it's all about that base

September 2, 2015

Rice University scientists have theoretically determined that the properties of atom-thick sheets of boron depend on where those atoms land.

An engineered surface unsticks sticky water droplets

August 31, 2015

The leaves of the lotus flower, and other natural surfaces that repel water and dirt, have been the model for many types of engineered liquid-repelling surfaces. As slippery as these surfaces are, however, tiny water droplets ...

Electrical circuit made of gel can repair itself

August 25, 2015

(Phys.org)—Scientists have fabricated a flexible electrical circuit that, when cut into two pieces, can repair itself and fully restore its original conductivity. The circuit is made of a new gel that possesses a combination ...

Scientists grow high-quality graphene from tea tree extract

August 21, 2015

(Phys.org)—Graphene has been grown from materials as diverse as plastic, cockroaches, Girl Scout cookies, and dog feces, and can theoretically be grown from any carbon source. However, scientists are still looking for a ...

0 comments

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.