Anupam Garg

Last updated
Anupam Garg
Alma mater
Known for Leggett–Garg inequality
Scientific career
Fields Physics
Institutions Northwestern University
Doctoral advisor N. David Mermin [1]

Anupam Garg is a professor in the department of Physics & Astronomy at Northwestern University, Illinois. He received his Ph.D. in 1983 from Cornell University. In 2012, he became a Fellow of the American Physical Society (APS) thanks to his work on molecular magnetism and macroscopic quantum phenomena.

Garg is best known for formulating the Leggett–Garg inequality, named for Anthony James Leggett and himself, which is a mathematical inequality fulfilled by all macrorealistic physical theories. [2] He is also known for the Garg-Onuchic-Ambegaokar model of charge transfer. [3] In addition, he discovered the phenomenon of topological quenching of the tunnel splitting in a toy Hamiltonian for spin tunneling, [4] that was subsequently found experimentally in the magnetic molecule Fe8. [5] His current research interests center around coherent state path integrals, especially as they pertain to quantum and semi-classical phenomena associated with the orientation of quantum mechanical spin.

Garg is the author of a graduate physics textbook, Classical Electromagnetism in a Nutshell, [6] and an undergraduate text, Mathematics with a Scientific Sensibility. [7]

See also

Related Research Articles

<span class="mw-page-title-main">Condensed matter physics</span> Branch of physics

Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid phases that arise from electromagnetic forces between atoms and electrons. More generally, the subject deals with condensed phases of matter: systems of many constituents with strong interactions among them. More exotic condensed phases include the superconducting phase exhibited by certain materials at extremely low cryogenic temperatures, the ferromagnetic and antiferromagnetic phases of spins on crystal lattices of atoms, the Bose–Einstein condensates found in ultracold atomic systems, and liquid crystals. Condensed matter physicists seek to understand the behavior of these phases by experiments to measure various material properties, and by applying the physical laws of quantum mechanics, electromagnetism, statistical mechanics, and other physics theories to develop mathematical models and predict the properties of extremely large groups of atoms.

<span class="mw-page-title-main">Maxwell's equations</span> Equations describing classical electromagnetism

Maxwell's equations, or Maxwell–Heaviside equations, are a set of coupled partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, electric and magnetic circuits. The equations provide a mathematical model for electric, optical, and radio technologies, such as power generation, electric motors, wireless communication, lenses, radar, etc. They describe how electric and magnetic fields are generated by charges, currents, and changes of the fields. The equations are named after the physicist and mathematician James Clerk Maxwell, who, in 1861 and 1862, published an early form of the equations that included the Lorentz force law. Maxwell first used the equations to propose that light is an electromagnetic phenomenon. The modern form of the equations in their most common formulation is credited to Oliver Heaviside.

<span class="mw-page-title-main">Physics</span> Scientific field of study

Physics is the natural science of matter, involving the study of matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, with its main goal being to understand how the universe behaves. A scientist who specializes in the field of physics is called a physicist.

<span class="mw-page-title-main">Magnetic monopole</span> Hypothetical particle with one magnetic pole

In particle physics, a magnetic monopole is a hypothetical elementary particle that is an isolated magnet with only one magnetic pole. A magnetic monopole would have a net north or south "magnetic charge". Modern interest in the concept stems from particle theories, notably the grand unified and superstring theories, which predict their existence. The known elementary particles that have electric charge are electric monopoles.

<span class="mw-page-title-main">Aharonov–Bohm effect</span> Electromagnetic quantum-mechanical effect in regions of zero magnetic and electric field

The Aharonov–Bohm effect, sometimes called the Ehrenberg–Siday–Aharonov–Bohm effect, is a quantum-mechanical phenomenon in which an electrically charged particle is affected by an electromagnetic potential, despite being confined to a region in which both the magnetic field and electric field are zero. The underlying mechanism is the coupling of the electromagnetic potential with the complex phase of a charged particle's wave function, and the Aharonov–Bohm effect is accordingly illustrated by interference experiments.

In physics, action at a distance is the concept that an object's motion can be affected by another object without being in physical contact with it; that is, the non-local interaction of objects that are separated in space. Coulomb's law and Newton's law of universal gravitation are based on action at a distance.

In theoretical physics, geometrodynamics is an attempt to describe spacetime and associated phenomena completely in terms of geometry. Technically, its goal is to unify the fundamental forces and reformulate general relativity as a configuration space of three-metrics, modulo three-dimensional diffeomorphisms. The origin of this idea can be found in an English mathematician William Kingdon Clifford's works. This theory was enthusiastically promoted by John Wheeler in the 1960s, and work on it continues in the 21st century.

In physics, the terms order and disorder designate the presence or absence of some symmetry or correlation in a many-particle system.

Quantum mechanics is the study of matter and its interactions with energy on the scale of atomic and subatomic particles. By contrast, classical physics explains matter and energy only on a scale familiar to human experience, including the behavior of astronomical bodies such as the moon. Classical physics is still used in much of modern science and technology. However, towards the end of the 19th century, scientists discovered phenomena in both the large (macro) and the small (micro) worlds that classical physics could not explain. The desire to resolve inconsistencies between observed phenomena and classical theory led to a revolution in physics, a shift in the original scientific paradigm: the development of quantum mechanics.

Amir Ordacgi Caldeira is a Brazilian physicist. He received his bachelor's degree in 1973 from the Pontifícia Universidade Católica do Rio de Janeiro, his M.Sc. degree in 1976 from the same university, and his Ph.D. in 1980 from University of Sussex. His Ph.D. advisor was the Physics Nobel Prize winner Anthony James Leggett. He joined the faculty at Universidade Estadual de Campinas (UNICAMP) in 1980. In 1984 he did post-doctoral work at the Kavli Institute for Theoretical Physics (KITP) at University of California, Santa Barbara and at the Thomas J. Watson Research Laboratory at IBM. In 1994–1995 he spent a sabbatical at the University of Illinois at Urbana-Champaign. He is currently a full professor at Universidade Estadual de Campinas. He was the recipient of the Wataghin Prize, from Universidade Estadual de Campinas, for his contributions to theoretical physics in 1986.

<span class="mw-page-title-main">Mesoscopic physics</span> Subdiscipline of condensed matter physics that deals with materials of an intermediate size

Mesoscopic physics is a subdiscipline of condensed matter physics that deals with materials of an intermediate size. These materials range in size between the nanoscale for a quantity of atoms and of materials measuring micrometres. The lower limit can also be defined as being the size of individual atoms. At the microscopic scale are bulk materials. Both mesoscopic and macroscopic objects contain many atoms. Whereas average properties derived from constituent materials describe macroscopic objects, as they usually obey the laws of classical mechanics, a mesoscopic object, by contrast, is affected by thermal fluctuations around the average, and its electronic behavior may require modeling at the level of quantum mechanics.

Quantum dissipation is the branch of physics that studies the quantum analogues of the process of irreversible loss of energy observed at the classical level. Its main purpose is to derive the laws of classical dissipation from the framework of quantum mechanics. It shares many features with the subjects of quantum decoherence and quantum theory of measurement.

The Leggett–Garg inequality, named for Anthony James Leggett and Anupam Garg, is a mathematical inequality fulfilled by all macrorealistic physical theories. Here, macrorealism is a classical worldview defined by the conjunction of two postulates:

  1. Macrorealism per se: "A macroscopic object, which has available to it two or more macroscopically distinct states, is at any given time in a definite one of those states."
  2. Noninvasive measurability: "It is possible in principle to determine which of these states the system is in without any effect on the state itself, or on the subsequent system dynamics."

The timeline of quantum mechanics is a list of key events in the history of quantum mechanics, quantum field theories and quantum chemistry.

The Leggett inequalities, named for Anthony James Leggett, who derived them, are a related pair of mathematical expressions concerning the correlations of properties of entangled particles. They are fulfilled by a large class of physical theories based on particular non-local and realistic assumptions, that may be considered to be plausible or intuitive according to common physical reasoning.

<span class="mw-page-title-main">Ravi Gomatam</span>

Ravi Veeraraghavan Gomatam is the director of Bhaktivedanta Institute and the newly formed Institute of Semantic Information Sciences and Technology, Mumbai. He teaches graduate-level courses at these institutes. He was an adjunct professor at Birla Institute of Technology & Science (BITS), Pilani, Rajasthan, India (1993–2015).

Macroscopic quantum phenomena are processes showing quantum behavior at the macroscopic scale, rather than at the atomic scale where quantum effects are prevalent. The best-known examples of macroscopic quantum phenomena are superfluidity and superconductivity; other examples include the quantum Hall effect, Josephson effect and topological order. Since 2000 there has been extensive experimental work on quantum gases, particularly Bose–Einstein condensates.

Quantum spin tunneling, or quantum tunneling of magnetization, is a physical phenomenon by which the quantum mechanical state that describes the collective magnetization of a nanomagnet is a linear superposition of two states with well defined and opposite magnetization. Classically, the magnetic anisotropy favors neither of the two states with opposite magnetization, so that the system has two equivalent ground states.

J. C. Séamus Davis is an Irish physicist whose research explores the world of macroscopic quantum physics. Davis concentrates upon the fundamental physics of exotic states of electronic, magnetic, atomic and space-time quantum matter. A specialty is development of innovative instrumentation to allow direct atomic-scale visualization or perception of the quantum many-body phenomena that are characteristic of these states.

Eugene John "Gene" Mele is a professor of physics at the University of Pennsylvania, where he researches quantum electric phenomena in condensed matter.

References

  1. "Anupam Garg". Physics Tree.
  2. Leggett, A. J.; Garg, Anupam (1985-03-04). "Quantum mechanics versus macroscopic realism: Is the flux there when nobody looks?" (PDF). Physical Review Letters. 54 (9). American Physical Society (APS): 857–860. Bibcode:1985PhRvL..54..857L. doi:10.1103/physrevlett.54.857. ISSN   0031-9007. PMID   10031639.
  3. Garg, Anupam; Onuchic, José Nelson; Ambegaokar, Vinay (1985). "Effect of friction on electron transfer in biomolecules". The Journal of Chemical Physics. 83 (9). AIP Publishing: 4491–4503. Bibcode:1985JChPh..83.4491G. doi:10.1063/1.449017. ISSN   0021-9606.
  4. Garg, Anupam (1993). "Topologically quenched tunnel splitting in spin systems without Kramers' degeneracy". Europhysics Letters. 22 (3). IOP Publishing: 205–210. doi:10.1209/0295-5075/22/3/008.
  5. Wernesdorfer, Wolfgang; Sessoli, Roberta (1999). "Quantum Phase Interference and Parity Effects in Magnetic Molecular Clusters". Science. 284: 133.
  6. Princeton University Press (2012).
  7. "Mathematics with a Scientific Sensibility".