Now, by creating a quantum mechanical analog of Ulam’s conjecture, researchers at the University of Illinois and the University of California have expanded the flexibility and controllability of quantum mechanical systems.
“Using photons, we can harness chaotic motion to control chemical reactions and to move quantum objects, such as nanoclusters, molecules and buckyballs,” said Martin Gruebele, a William H. and Janet Lycan Professor of Chemistry, and the director of the Center for Biophysics and Computational Biology at Illinois.
Gruebele and co-author Peter Wolynes, a professor of chemistry and biochemistry at the University of California, describe their work in a paper accepted for publication in Physical Review Letters and posted on the journal’s Web site.
Given sufficient time, classical chaotic motion will spontaneously connect two points in phase space with arbitrary precision. In 1956, American mathematician Stanislaw Ulam conjectured that owing to this phase space-filling aspect of chaotic trajectories, a minimal series of energy expenditures would suffice to transfer a body from one point to another much more rapidly than by spontaneous motion.
Ulam’s conjecture is now routinely used to steer spacecraft around the solar system with minimal energy expenditure.
“The idea is that a complex system like our solar system has lots of planets, moons, and asteroids that can fling spacecraft gravitationally anywhere you want,” said Gruebele, who is also a professor of physics and biophysics, and a researcher at the Beckman Institute. “Rather than powering a rocket on a brute force, direct route, you can shoot your spacecraft near some moon, and let the moon do most of the work.”
Using photons as an energy source, electrons within molecules can move in much the same way as spacecraft in the solar system. But, there is a hitch: Quantum mechanics, not Newtonian dynamics, must be used to describe the motions. In quantum mechanics, the system is described by a wave function, or quantum state.
In their quantum mechanical analog of Ulam’s conjecture, Gruebele and Wolynes show there are limits on how efficiently an external force can nudge a system from a given initial state to a target state. They use the concept of a “state space” to describe all the possible quantum states of the system.
“We can calculate where this initial state will most likely go, and we can calculate where the target state will most likely come from,” Gruebele said. “We can then identify places in state space where the two are closest to one another.”
Those locations are where energy is most efficiently applied to perform the desired quantum transformation from initial state to target state. The researchers’ equations also tell them how many photons are needed, and set fundamental limits on the time required.
“We can wait for the best possible moment to use the least amount of energy,” Gruebele said. “What we have is a fast and accurate method for computing the most efficient way of steering a quantum system between two specified states.”
James E. Kloeppel | EurekAlert!
NASA spacecraft investigate clues in radiation belts
28.03.2017 | NASA/Goddard Space Flight Center
Researchers create artificial materials atom-by-atom
28.03.2017 | Aalto University
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Life Sciences
28.03.2017 | Information Technology
28.03.2017 | Physics and Astronomy