Fellow of the American Physical Society

Associate Editor Physical Review A

Ph.D., University of New Mexico, 1985

Research Associate, Max Planck Institute for Quantum Optics, 1985-87

Staff Scientist, Instituto de Optica, Madrid, Spain, 1988-90

Assistant Professor to Professor, University of Arkansas, 1990-present

Julio Gea-Banacloche got his Ph.D. at the University of New Mexico working on the quantum theory of the free-electron laser under Marlan O. Scully. He has done theoretical work in laser physics, quantum optics, and quantum information. He became an Associate Editor of Physical Review A in the year 2000, and was made a Fellow of the American Physical Society in 2005. You can find out more about him at his personal home page: http://comp.uark.edu/ ~jgaebana/.

QUANTUM-CLASSICAL CORRESPONDENCE

My main interest has always been learning about the ways in which quantum mechanical systems are different from classical ones. Of course, at the most basic level everything is quantum mechanical; however, many physical systems can be described to an excellent approximation by the equations and concepts of classical physics. Finding out when it is all right to do so, and when one should use, instead, the (typically) much more computationally demanding and often counterintuitive formalism of quantum mechanics is not always an easy task. Many times, quantum mechanics just results in small corrections to the classical results. Other times the predictions of quantum mechanics can be very different from those of classical physics. Sometimes both situations occur in the same physical system, for different initial conditions: a few years ago I predicted that this would be the case for a very simple system of quantum optics, namely, a single atom interacting with a single mode of the electromagnetic field. This prediction has recently been verified experimentally, and, with researchers at Miami University and the University of Maryland, I am currently working on extending some of these insights to other, more complicated quantum optical systems.

An important source of differences between classical and quantum systems is the phenomenon called entanglement. When two quantum systems become entangled, each of them loses, to some degree, part of its identity. They also develop correlations that are much stronger than anything classical systems could exhibit. Experiments that test these correlations exhibit, from a classical viewpoint, a sort of pseudo-telepathy, or a faster-than-light communication that, however, does not violate the theory of relativity. A new subfield of physics, called quantum information, has developed in recent years, devoted to exploring ways in which these features might be useful for quantum communication and quantum computation. I have been active in this field for several years now, and I have also become one of the Associate Editors of the journal Physical Review A in charge of the Quantum Information section.

My main contribution to the field of quantum information has been the observation that the quantum mechanical nature of the fields used to manipulate the quantum information carriers themselves--often called "qubits", or "quantum bits"--might lead to unpredictable errors in the performance of the quantum logical operations (such as encoding or decoding the information, and carrying out calculations on it). The lower bound on the size of these errors can be made smaller by increasing the energy of the control system. This has led me to a prediction of a minimum energy requirement for quantum computation which has given rise to some controversy and which is one of my proposed areas of research for the immediate future. In particular, I wish to establish if there are any ways to get around this constraint and if it might also apply to some classical computing schemes, in an appropriate limit.

A very personal introduction to the subject of quantum computing, and to the work mentioned above, can be found in this paper, which was published in the Japanese "Mathematical Sciences Magazine" earlier this year (2005).

Another project that I'm involved with concerns the possible practical applications of arrays of quantum dots that could be manufactured here, at the U of A facilities. In particular, I believe that a scheme borrowed from atomic physics might be used to switch on and off the absorptive properties of a medium made of layers of such quantum dots. This project is a currently funded collaboration with professors Xiao and Salamo.

Finally, I have occasionally developed computer animations and programs to help visualize physics concepts. Those interested can find a list of some of these projects here.