Anthony J Leggett

Professor

D. Phil. Physics Magdalen College, Oxford University 1964

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.

Other Activities

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.

Honors and awards:

• 2003 Nobel Prize in Physics (with V. L. Ginzburg and A. A. Abrikosov)
• 2002/2003 Wolf Foundation Prize for research on condensed forms of matter (with B. I. Halperin)
• 1999-Foreign Member, Russian Academy of Sciences
• 1999-Eugene Feenberg Memorial Medal
• 1998-Honorary Fellow, Institute of Physics, UK
• 1997-Elected Foreign Associate, National Academy of Sciences
• 1991-Paul Dirac Medal and Prize (British Institute of Physics) (The Eighth Simon Prize was awarded in 1976, the Tenth London Award in 1978, while the Maxwell Prize and Dirac prizes are annual).
• 1985-Fellow of the American Physical Society (November 1985)
• 1981-Ninth Simon Memorial Prize of the British Institute of Physics
• 1981-Eleventh Fritz London Memorial Award
• 1980-Fellow of the Royal Society
• Knighted, Order of the British Empire (KBE) “for services to physics” by Queen Elizabeth II, 2005
• 1975-Maxwell Medal and Prize of the British Institute of Physics

Selected Publications:

• A.J.Leggett,Quantum Liquids:Bose condensation and Cooper pairing in condensed matter systems (Oxford University Press, 2006).
• A. J. Leggett. The Problems of Physics. (Oxford University Press: Oxford & N.Y.). (1987). [German translation: Physik: Probleme, Themen, Fragen, (Birkhaüser Verlag, Basel, 1989); Japanese translation: Butsurigaku no Susume, Kinokuniya, Tokyo, 1990) Italian translation: I Problemi Della Fisica (Einaudi, Rome, 1991)].
• S. Zhang, A. J. Leggett. Universal properties of the ultracold Fermi gas. Phys. Rev. A, 79:2, 023601 (2009).
• Leggett, A. J. Perspective - Quantum liquids [Editorial Material]. Science, 319:5867, 1203-1205 (Feb. 2008).
• S. Zhang and A. J. Leggett. Sum-rule analysis of radio-frequency spectroscopy of ultracold Fermi gas. Physical Review A, 77:3 033614 (2008)
• A. J. Leggett. Realism and the physical world. Rep. Prog. Phys. 71 022001 (2008).
• A. J. Leggett, How far do EPR-bell experiments constrain physical collapse theories?, J. Phys. A: Math. Theor. 40, 3141-3149 (2007).
• A. J. Leggett. What DO we know about high T_c? Nature Physics, 2:3, 134-136 (2006).
• A. J. Leggett. Some thoughts about two-dimensionality and cuprate superconductivity. J. Superconductivity & Novel Magn. 19:3-5 187-192 (2006)
• A. J. Leggett. The quantum measurement problem. Science 307, 871-872 (2005).
• A. J. Leggett. Nuclear magnetic resonance in ultra-small samples of superfluid ³He. Syn. Metals 141, 51-58 (2004).
• A. J. Leggett. Nobel lecture: Superfluid ³He: The early days as seen by a theorist. Rev. Mod. Phys. 76, 999-1011 (2004).
• A. J. Leggett. 2003 Nobel prize in physics for theoretical work on superfluid He-3 . Nobel Lecture . ChemPhysChem 5, 946-958 (2004).
• A. J. Leggett. Superfluidity in a crystal? Science 305, 1921-1922 (2004).
• A. J. Leggett. Physics - Superconducting qubits - a major roadblock dissolved? Science 296, 861-862 (2002).
• A. J. Leggett. Testing the limits of quantum mechanics: motivation, state of play, prospects. J. Phys.: Cond. Matt. 14, R415-451 (2002).
• A. J. Leggett. Bose-Einstein condensation in the alkali gases: Some fundamental concepts. Rev. Mod. Phys. 73, 307-356 (2001). Erratum: RMP 75, 1083 (2003).
• A. J. Leggett. Superfluidity. Rev. Mod. Phys. 71, S318-323 (1999).
• A. J. Leggett. Cuprate superconductivity: Dependence of Tc on the c-axis layering structure. Phys. Rev. Lett. 83, 392-395 (1999).
• A. J. Leggett. The significance of the MQC experiment. J. Superconductivity 12, 683-687 (1999).
• D. A. Wollman, D. J. Van Harlingen, W. C. Lee, D. M. Ginsberg, and A. J. 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).
• A. O. Caldeira and A. J. Leggett. Quantum tunneling in a dissipative system. Ann. Phys. 149, 374-456 (1983).
• A. J. Leggett. A theoretical description of the new phases of liquid ³He. Rev. Mod. Phys. 47, 331-414 (1975).