I am a theoretical physicist. Topics I have worked on in the past include the connections between particle physics and cosmology, properties of topological defects, nonperturbative phenomena in quantum field theory, and quantum aspects of the early universe and of black holes. Since the mid-1990s, my central interest has been in the theory of quantum information, quantum computing, and quantum error correction.

Broadly speaking, quantum information science addresses how the principles of quantum physics can be harnessed to improve the acquisition, transmission, and processing of information. A quantum computer would be a new type of machine that, by exploiting the unusual quantum properties of information, could perform certain types of calculations far more efficiently than any foreseeable classical computer. I'm particularly interested in developing new schemes for protecting intricate quantum systems from decoherence and other sources of error. Here is a 6-minute animated introduction to the subject.

For further information about quantum computation, and other useful links, see the Physics 219 home page.

In 2000 I founded the Institute for Quantum Information (IQI), as part of the initiative in Information Technology Research launched by the National Science Foundation. In 2011 the IQI become a part of the Institute for Quantum Information and Matter (IQIM), an NSF Physics Frontiers Center.