Dr. Svetlana Malinovskaya of the Department of Physics and Engineering Physics recently presented a Physics Colloquium at University of Nevada, Reno, where she assessed the latest developments in the quantum control of ultra-cold atoms and molecules and proposed potential solutions to the problem of decoherence. Quantum control is essential to the establishment and implementation of quantum computing, an extremely fast and powerful technology that would use the quantum state of atoms and molecules to store information rather than the electrical switches currently used in computers. A hindrance to its implementation is a phenomenon known as decoherence, which can be described as a loss of information to the environment.
One proposed way to limit decoherence is to take advantage of the special properties of ultra-cold atomic and molecular systems. Albert Einstein predicted that matter would behave in a different manner at temperatures that approach absolute zero (0 K or −273.15 °C). Under such conditions, atoms and molecules must be described with quantum properties rather than classical properties, and quantum effects are observed even at macroscopic scale. The state of matter in this condition is known as an Einstein condensate, and it is often considered to be the fifth state of matter. This state has considerable potential for quantum computing applications because of new features in matter systems free from thermal motion.
The centennial Nobel Prize for Physics in 2001 was awarded to the researchers who first produced this condensate with a system of atoms, but doing so with molecules has proven to be more difficult. Dr. Malinovskaya has proposed the implementation of optical frequency combs, or pulsed electromagnetic waves, for cooling of internal degrees of freedom in molecules (rotations and vibrations that stand in the way of achievement of molecular condensate). This provides a coherent accumulation of the population in the target state, accompanied by a negligible population of the excited state. This result is particularly sound in the context of prevention of decoherence.
Dr. Malinovskaya’s research is being conducted in collaboration with researchers from the University of Nevada, Reno and the University of Connecticut. Stevens students and Ph.D. candidates are also deeply involved in the research. Thomas Collins, a Ph.D. candidate, played an active role in this research, contributing to five research articles published in the top journals including Physical Review and Optics Letters. Spencer Horton, who graduated with a bachelor's degree in Engineering Physics and master's degree in Nanotechnology in May 2012, completed his thesis on the studies of decoherence at ultracold temperatures, and under the supervision of Dr. Malinovskaya proposed the technique to mitigate the impact of decoherence by using modulated optical frequency combs. He will continue his graduate studies at Stony Brook University. The whole research group will participate with four presentations at the Annual Meeting of the American Physical Society which will take place next week, June 4 – 8, in Anaheim, Cali.