Quantum control of molecules could lead to extremely fast computers
In the quantum world, making the simple atom behave is one thing, but making the more complex molecule behave is another story.
Now Northwestern University scientists have figured out an elegant way to stop a molecule from tumbling so that its potential for new applications can be harnessed: shine a single laser on a trapped molecule and it instantly cools to the temperature of outer space, stopping the rotation of the molecule.
"It's counterintuitive that the molecule gets colder, not hotter when we shine intense laser light on it," said Brian Odom, who led the research. He is an assistant professor of physics and astronomy in the Weinberg College of Arts and Sciences. "We modify the spectrum of a broadband laser, such that nearly all the rotational energy is removed from the illuminated molecules. We are the first to stop molecular tumbling in such a powerful yet simple way."
It is not very difficult to trap many types of molecules and hold them precisely in place, Odom said, but they stubbornly persist in rotating just as much as if they were not trapped at all. Using their customized laser, he and his colleagues cooled singly charged aluminum monohydride molecules from room temperature to 4 degrees Kelvin (minus 452 degrees Fahrenheit) in a fraction of a second. The abrupt temperature drop stopped the molecules' normally persistent tumbling motion in its tracks.
Such control of molecules, of their rotational and vibrational states, is essential to using molecules in the construction of superfast quantum computers -- machines whose processing power would be exponentially faster than today's computers.
The new technique is faster, easier and more practical and efficient than techniques developed thus far to control molecules. Details will be published Sept. 2 by the journal Nature Communications.
Previously, it was long assumed that far too many lasers would be required to cool molecular rotations. However, broadband laser light contains many different frequency components, and the Northwestern researchers used those components to custom design a laser for their task. They filtered out the part of the spectrum that causes molecules to start spinning faster (and become hotter) while leaving in the useful frequency components that slows the molecules down (and also cools them).
Also noteworthy, Odom said, is that they cooled the molecule to its very lowest quantum rotational state using a room-temperature apparatus, not the cumbersome liquid helium cryostats some other researchers have used.
"In our quantum world, every type of motion has only certain allowed energies," said Odom, an atomic physicist. "If I want to slow down a molecule, quantum mechanics tells me that it happens in steps. And there is a very lowest step that we can get the molecule down to, which is what we've done."
Odom and his team chose to work with singly charged aluminum monohydride molecules because the molecule does not vibrate when it interacts with a laser.
"By choosing the right molecule we were able to stop the molecules from rotating without worrying about the vibrations," Odom said.
Aluminum monohydride molecules are inexpensive and could be used in wide range of applications, beyond quantum computing.
"There is a lot you can do if you get one species of molecule under control, such as we've done in this study," Odom said.
In addition to quantum information processing, applications that could springboard off this new ability to control molecular rotors include ultracold quantum-controlled chemistry and tests of whether fundamental constants are truly static or if they vary in time.
The title of the paper is "Broadband optical cooling of molecular rotors from room temperature to the ground state."
In addition to Odom, authors of the paper are Chien-Yu Lien, Christopher M. Seck, Yen-Wei Lin, Jason H.V. Nguyen, David A. Tabor, all of Northwestern.
Megan Fellman | Eurek Alert!
NASA's Fermi catches gamma-ray flashes from tropical storms
25.04.2017 | NASA/Goddard Space Flight Center
DGIST develops 20 times faster biosensor
24.04.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
25.04.2017 | Physics and Astronomy
25.04.2017 | Materials Sciences
25.04.2017 | Life Sciences