Toward a Quantum Computer, One Dot at a Time

Jan 19, 2006

Researchers at the University of Pittsburgh have developed a way to create semiconductor islands smaller than 10 nanometers in scale, known as quantum dots. The islands, made from germanium and placed on the surface of silicon with two-nanometer precision, are capable of confining single electrons.

“We believe this development moves us closer to our goal of constructing a quantum computer,” said Jeremy Levy, Pitt professor of physics and astronomy and director of the Pittsburgh-based Center for Oxide-Semiconductor Materials for Quantum Computation. Levy and colleagues reported on the advance in a paper published in October 2005 in the journal Applied Physics Letters.

Quantum computers do not yet exist, but it is known that they can bypass all known encryption schemes used today on the Internet. Quantum computers also are capable of efficiently solving the most important equation in quantum physics: the Schrödinger equation, which describes the time-dependence of quantum mechanical systems. Hence, if quantum computers can be built, they likely will have as large an impact on technology as the transistor.

Electrons have a property known as “spin,” which can take one of two directions-clockwise and counter-clockwise. Because of their quantum-mechanical nature, electrons can spin in both directions at once. That bizarre property allows the spin to be used as a “quantum bit” in a quantum computer. The ability to confine individual electrons, as opposed to “puddles” of electrons used in conventional computer technology, is essential for the working of a quantum computer.

The next step, said Levy, is to perform electronic and optical measurements on these materials to prove that there is indeed one electron on each quantum dot and to probe the coupling between the spins of neighbor electrons. “We can do that now because we have this control over the spacing and the size,” he said.

The results achieved by Levy and colleagues are an example of “essentially nano” research, which involves manipulating properties at the smallest scales-from one to 20 nanometers.

Pitt has invested heavily in nanoscale research, beginning with the establishment of its Institute for NanoScience and Engineering (INSE), and continuing with the NanoScale Fabrication and Characterization Facility, which contains core technology such as electron-beam lithography, transmission electron microscopes, and a state-of-the-art cleanroom environment. The INSE is an integrated, multidisciplinary organization that brings coherence to the University's research efforts and resources in the fields of nanoscale science and engineering. For more information, visit www.nano.pitt.edu.

Other researchers on the study were John T. Yates Jr., R.K. Mellon Professor of Chemistry and Physics at Pitt; former Pitt chemistry graduate student Olivier Guise; Joachim Ahner of Pittsburgh-based Seagate Technology; and Venugopalan Vaithyanathan and Darrell G. Schlom of Pennsylvania State University.

This research was supported by the Defense Advanced Research Projects Agency's Quantum Information Science and Technology Program.

Source: University of Pittsburgh

Explore further: Simulations provide new insight into emerging nanoelectronic device

add to favorites email to friend print save as pdf

Related Stories

Physicists find a new form of quantum friction

20 hours ago

Physicists at Yale University have observed a new form of quantum friction that could serve as a basis for robust information storage in quantum computers in the future. The researchers are building upon ...

Top-precision optical atomic clock starts ticking

12 hours ago

A state-of-the-art optical atomic clock, collaboratively developed by scientists from the University of Warsaw, Jagiellonian University, and Nicolaus Copernicus University, is now "ticking away" at the National ...

Rapid data transfer thanks to quantum physics

Feb 25, 2015

RUB engineers have developed a new concept for accelerating data transfer in server farms. To this end, the team at the Chair of Photonics and Terahertz Technology applies a quantum-mechanical variable, i.e. ...

Image sensors that behave like biological retinas

Feb 18, 2015

Ever since the invention of the first camera obscura and the advent of photography in the 19th century, scientists have been fascinated by the use of light sensors to capture the world around us from the ...

Recommended for you

Buckybomb shows potential power of nanoscale explosives

8 hours ago

(Phys.org)—Scientists have simulated the explosion of a modified buckminsterfullerene molecule (C60), better known as a buckyball, and shown that the reaction produces a tremendous increase in temperatur ...

Medical nanoparticles: local treatment of lung cancer

10 hours ago

Nanoparticles can function as carriers for medicines to combat lung cancer: Working in a joint project at the NIM (Nanosystems Initiative Munich) Excellence Cluster, scientists from the Helmholtz Zentrum ...

User comments : 0

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.