Could a quantum motor do work?

Jul 07, 2009 By Miranda Marquit feature

(PhysOrg.com) -- Ever since the idea of a quantum world was discovered, physicists have been trying their best to create applications and uses that mirror the accomplishments of the classical world. However, due to the fact that the quantum world is often quirky and not always well understood, sometimes these attempts go awry. In the case of a quantum motor, though, a theoretical paper out of the University of Augsburg in Germany might shed some light on how some of the quantum quirks might be overcome, resulting in an ac-driven quantum motor.

Sergey Denisov is one of the coauthors of “ac-Driven Atomic Quantum Motor,” which appears in Physical Review Letters. Along with Alexey Ponomarev and Peter Hänggi, Denisov worked to set up a quantum motor. With a quantum motor, rotation would occur both clockwise and counterclockwise, cancelling out movement and resulting in no work output. Denisov explains how the Augsburg team managed to overcome this problem: “We have to use a starter. Using two atoms, we are able to get net movement for our motor. One atom serves as a carrier, and the other as the driver starter.”

The quantum motor is set up using cold atoms trapped in an optical lattice shaped into a ring. A magnetic field is applied to the ring. A carrier atom is charged, allowing it to “feel” the magnetic field and forcing it to move. However, this single atom moves in such a way as to produce no net motion. This is where the starter atom comes in. Denisov says that an uncharged atom is introduced into the system, forcing net movement into the system. Further probing with the use of a force akin to gravity yielded the theoretical possibility that this motor could work under load.

Denisov points out that so far, this work is just theoretical. “We are not as concerned about application and technology,” he says, “although this is likely to have its uses in the future. We are more excited from a theoretical point of view. We wanted to know how many atoms are needed to make a quantum motor. The next step is to see what happens if we introduce more atoms into the system. We want to expand our set up to see if we could get more work out of the motor.”

However, before the Augsburg group gets too excited about looking into expanding their system, the two-atom motor needs to be tested experimentally. “While it would be difficult to set up such an experiment,” Denisov acknowledges, “it is doable.” The biggest problem, he says, is that atoms tend to adsorb and emit photons when excited to this degree. These photons would cause stability problems for the system. While a solution to that issue would have to be found, Denisov nonetheless believes that testing should be possible.

“Optical potential has been looked at for quite some time, and access to cold atoms is not so rare. There are at least 15 labs that can prepare such a set of atoms. Besides, similar experiments have been done using a cloud-like set-up. With some effort, it should be possible to test our theory in the lab using current technology.”

More information: A.V. Ponomarev, S. Denisov, and P. Hänggi, “ac-Driven Atomic Quantum Motor,” (2009). Available online: http://link.aps.org/doi/10.1103/PhysRevLett.102.230601 .

Copyright 2009 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

Explore further: Unleashing the power of quantum dot triplets

add to favorites email to friend print save as pdf

Related Stories

Can alkaline earth metals be used in quantum computing?

Nov 14, 2008

(PhysOrg.com) -- "There are a number of different proposals for quantum computing," Andrew Daley tells PhysOrg.com. "These include solid state or semiconductor as well as atomic and molecular systems. We are considering atomic ...

Taking entanglement beyond one ebit

Jan 23, 2007

“Entanglement is a main part of quantum mechanics, and it is important to obtain a high degree of it in physical systems,” Lucas Lamata tells PhysOrg.com. Lucas Lamata is a scientist with the Institute for Fundamental Mathem ...

Using Current Technology to Prepare for Quantum Computing

Aug 14, 2006

“If we use the environment in the process,” explains Almut Beige, “we don’t need to control everything.” Dr. Beige and two students working with her at Imperial College London, Jeremy Metz and Michael Trupke, have ...

Controlling Photons for Use in Quantum Computing

Feb 13, 2007

“Quantum information science makes use of the quantum nature of particles to perform computation,” Gerhard Rempe explains to PhysOrg.com. “One approach is to use single particles of light – photons – as the basis ...

Combining solid-state physics with quantum optics

Oct 19, 2007

One of the more interesting advances in science is the use of the atom chip. As the demands of technology require smaller and smaller components, studying the fundamentals of physics at the quantum level will become increasingly ...

Recommended for you

Unleashing the power of quantum dot triplets

Jul 24, 2014

Quantum computers have yet to materialise. Yet, scientists are making progress in devising suitable means of making such computers faster. One such approach relies on quantum dots—a kind of artificial atom, ...

Exotic state of matter propels quantum computing theory

Jul 23, 2014

So far it exists mainly in theory, but if invented, the large-scale quantum computer would change computing forever. Rather than the classical data-encoding method using binary digits, a quantum computer would process information ...

Quantum leap in lasers brightens future for quantum computing

Jul 22, 2014

Dartmouth scientists and their colleagues have devised a breakthrough laser that uses a single artificial atom to generate and emit particles of light. The laser may play a crucial role in the development of quantum computers, ...

Boosting the force of empty space

Jul 22, 2014

Vacuum fluctuations may be among the most counter-intuitive phenomena of quantum physics. Theorists from the Weizmann Institute (Rehovot, Israel) and the Vienna University of Technology propose a way to amplify ...

User comments : 0