Anthony J. Leggett
John D. and Catherine T. MacArthur chair and
Center for Advanced Study Professor of Physics
Sir Anthony J. Leggett, the John D. and Catherine T. MacArthur Professor and Center for Advanced Study Professor of Physics, has been a faculty member at Illinois since 1983. He is widely recognized as a world leader in the theory of low-temperature physics, and his pioneering work on superfluidity was recognized by the 2003 Nobel Prize in Physics. He is a member of the National Academy of Sciences, the American Philosophical Society, the American Academy of Arts and Sciences, the Russian Academy of Sciences (foreign member), and is a Fellow of the Royal Society (U.K.), the American Physical Society, and the American Institute of Physics. He is an Honorary Fellow of the Institute of Physics (U.K.). He was knighted (KBE) by Queen Elizabeth II in 2004 "for services to physics."
Professor Leggett has shaped the theoretical understanding of normal and superfluid helium liquids and other strongly coupled superfluids. He set directions for research in the quantum physics of macroscopic dissipative systems and use of condensed systems to test the foundations of quantum mechanics. His research interests lie mainly within the fields of theoretical condensed matter physics and the foundations of quantum mechanics. He has been particularly interested in the possibility of using special condensed-matter systems, such as Josephson devices, to test the validity of the extrapolation of the quantum formalism to the macroscopic level; this interest has led to a considerable amount of technical work on the application of quantum mechanics to collective variables and in particular on ways of incorporating dissipation into the calculations. He is also interested in the theory of superfluid liquid 3He, especially under extreme nonequilibrium conditions, in high-temperature superconductivity, and in the newly realized system of Bose-condensed atomic gases.
Research Area: theoretical condensed matter physics, low-temperature phenomena, foundations of quantum mechanics, quantum fluids, statistical physics, macroscopic quantum systems, quantum theory of measurement
Description of Current Research
Aspects of Cuprate Superconductivity
We are exploring a scenario for cuprate superconductivity in which a major factor is the reduction, due to increased screening by the Cooper pairs, of the long-wavelength, mid-infrared-frequency part of the Coulomb interaction. In addition, independently of this scenario, we are attempting to explain the c-axis transport properties of the cuprates and are looking at some problems associated with the "pseudogap" regime and with the peculiar features resulting from the existence of gap nodes.
Experimentally Oriented Studies of Basic Conceptual Issues in the Foundations of Quantum Mechanics
We are studying the application of the quantum-mechanical formalism to the description of various experiments that severely test one’s understanding of its meaning. In addition, we study possible alternative explanations of ostensibly relevant experiments in the literature.
Superfluidity and Phase Coherence in Very Degenerate Atomic Gases
Studies are being made of the superfluid density of an arbitrary many-body system, possible phase-coherence and interference experiments in Bose-condensed atomic gases, superfluidity in very degenerate dilute Fermi gases, and thermal transport in the ultralow-temperature regime of superfluid 3He.
Selected Publications
Leggett, AJ. The quantum measurement problem. Science 307, 871-872 (2005).
Leggett, AJ, Ruggiero, B, and Silvestrini, P. Quantum Computing and Quantum Bits in Mesoscopic Systems 1-273 (2004).
Leggett, AJ. Nuclear magnetic resonance in ultra-small samples of superfluid 3He. Syn. Metals 141, 51-58 (2004).
Leggett, AJ. Nobel lecture: Superfluid 3He: The early days as seen by a theorist. Rev. Mod. Phys. 76, 999-1011 (2004).
Leggett, AJ. 2003 Nobel prize in physics for theoretical work on superfluid 3He . Nobel Lecture. ChemPhysChem 5, 946-958 (2004).
Leggett, AJ. Superfluidity in a crystal? Science 305, 1921-1922 (2004).
Leggett, AJ. "Testing the limits of quantum mechanics: motivation, state of play, prospects," J. Phys. CM 14, R415-451 (2002). (local PDF file)
Leggett, AJ. Bose-Einstein condensation in the alkali gases; Some fundamental concepts. Rev. Mod. Phys. 73, 307-356 (2001).
Leggett, AJ. The significance of the MQC experiment. J. Superconductivity 12, 683-7 (1999).
Leggett, AJ. BEC: The alkali gases from the perspective of research on liquid helium, Atomic Physics 16, ed. W. F. Baylis and G. W. F. Drake, AIP Conference proceedings 477, Woodbury, New York, pp.154-169 (1999).
Leggett, AJ. Superfluidity, Rev. Mod. Phys. 71, S318-23 (1999).
Leggett, AJ. Cuprate superconductivity: dependence of Tc on the c-axis layering structure. Phys. Rev. Lett. 83, 392-395 (1999).
Wollman, D., DJ Van Harlingen, WC Lee, DM Ginsberg, and AJ Leggett. Experimental determination of the superconducting pairing state in YBCO from the phase coherence of YBCO-Pb dc SQUIDs. Phys. Rev. Lett. 71, 2134-2137 (1993).
Annett, JF, N Goldenfeld and AJ Leggett, Experimental constraints on the pairing state of the cuprate superconductors: An emerging consensus,Physical Properties of High Temperature Superconductors V, ed. D.M. Ginsberg (World Scientific Publishing Co., Singapore, 1996) pp. 375-461.
Leggett, AJ.Quantum mechanics at the macroscopic level, in Chance and Matter, ed. J. Souletie, J. Vannimenus, and R. Stora (North Holland, Amsterdam, 1987), pp. 395-506.
Caldiera, A. O. and A.J. Leggett, Quantum tunneling in a dissipative system. Ann. Phys. (NY) 149, 374-456 (1983).
Leggett, AJ. A theoretical description of the new phases of liquid 3He. Revs. Mod. Phys. 47, 331-414 (1975).
Honors and Awards
- Knight Commander, Order of the British Empire (KBE), 2005
- Nobel Prize in Physics, 2003 (additional information)
- Wolf Foundation Prize in Physics, 2002-03
- Member, National Academy of Sciences, 1997
- Eugene Feenberg Memorial Medal, 1999
- Foreign Member, Russian Academy of Sciences, 1999
- Honorary Fellow, Institute of Physics (UK), 1999
- Member, American Academy of Arts and Sciences, 1996
- Member, American Philosophical Society, 1991
- Paul Dirac Medal, Institute of Physics, 1991
- Fellow, American Physical Society, 1985
- Fellow, American Institute of Physics, 1985
- Eleventh Fritz London Memorial Award, 1981
- Ninth Simon Memorial Prize, Institute of Physics, 1981
- Fellow, Royal Society (UK), 1980
- Maxwell Medal and Prize, Institute of Physics, 1975
