Mott insulators are a class of materials that are expected to conduct electricity according to conventional band theories, but turn out to be insulators. These insulators fail to be correctly described by band theories of solids due to their strong electron–electron interactions, which are not considered in conventional band theory. A Mott transition is a transition from a metal to an insulator, driven by the strong interactions between electrons. One of the simplest models that can capture Mott transition is the Hubbard model.
In physics, topological order is a kind of order in the zero-temperature phase of matter. Macroscopically, topological order is defined and described by robust ground state degeneracy and quantized non-abelian geometric phases of degenerate ground states. Microscopically, topological orders correspond to patterns of long-range quantum entanglement. States with different topological orders cannot change into each other without a phase transition.
Octopus is a software package for performing Kohn–Sham density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations.
Oleg Sushkov is a professor at the University of New South Wales and a leader in the field of high temperature super-conductors. Educated in Russia in quantum mechanics and nuclear physics, he now teaches in Australia.
Jozef T. Devreese was a Belgian scientist, with a long career in condensed matter physics. He was professor emeritus of theoretical physics at the University of Antwerp. He died on November 1, 2023.
Marvin Lou Cohen is an American–Canadian theoretical physicist. He is a physics professor at the University of California, Berkeley. Cohen is a leading expert in the field of condensed matter physics. He is widely known for his seminal work on the electronic structure of solids.
Steven R. White is a professor of physics at the University of California, Irvine. He is a condensed matter physicist who specializes in the simulation of quantum systems. He graduated from the University of California, San Diego; he then received his Ph.D. at Cornell University, where he was a shared student with Kenneth Wilson and John Wilkins.
The topological entanglement entropy or topological entropy, usually denoted by , is a number characterizing many-body states that possess topological order.
Quantum dimer models were introduced to model the physics of resonating valence bond (RVB) states in lattice spin systems. The only degrees of freedom retained from the motivating spin systems are the valence bonds, represented as dimers which live on the lattice bonds. In typical dimer models, the dimers do not overlap.
DP is a free software package for physicists implementing ab initio linear-response TDDFT in frequency-reciprocal space and on a plane wave basis set. It allows to calculate both dielectric spectra, such as EELS, IXSS and CIXS, and also optical spectra, e.g. optical absorption, reflectivity, refraction index. The systems range from periodic/crystalline solids, to surfaces, clusters, molecules and atoms made of insulators, semiconductors and metal elements. It implements the RPA, the TDLDA or ALDA plus other non-local approximations, including or neglecting local-field effects. It is distributed under the scientific software open-source academic for free license.
Patrick A. Lee is a professor of physics at the Massachusetts Institute of Technology (MIT).
Xiao-Gang Wen is a Chinese-American physicist. He is a Cecil and Ida Green Professor of Physics at the Massachusetts Institute of Technology and Distinguished Visiting Research Chair at the Perimeter Institute for Theoretical Physics. His expertise is in condensed matter theory in strongly correlated electronic systems. In Oct. 2016, he was awarded the Oliver E. Buckley Condensed Matter Prize.
David Matthew Ceperley is a theoretical physicist in the physics department at the University of Illinois Urbana-Champaign or UIUC. He is a world expert in the area of Quantum Monte Carlo computations, a method of calculation that is generally recognised to provide accurate quantitative results for many-body problems described by quantum mechanics.
In physics, the plasmaron was proposed by Lundqvist in 1967 as a quasiparticle arising in a system that has strong plasmon-electron interactions. In the original work, the plasmaron was proposed to describe a secondary peak in the photoemission spectral function of the electron gas. More precisely it was defined as an additional zero of the quasi-particle equation . The same authors pointed out, in a subsequent work, that this extra solution might be an artifact of the used approximations:
We want to stress again that the discussion we have given of the one-electron spectrum is based on the assumption that vertex corrections are small. As discussed in the next section recent work by Langreth [29] shows that vertex corrections in the core electron problem can have a quite large effect on the form of satellite structures, while their effect on the quasi particle properties seems to be small. Preliminary investigations by one of us (L.H.) show similar strong vertex effects on the conduction band satellite. The details of the plasmaron structure should thus not be taken very seriously.
The toric code is a topological quantum error correcting code, and an example of a stabilizer code, defined on a two-dimensional spin lattice. It is the simplest and most well studied of the quantum double models. It is also the simplest example of topological order—Z2 topological order (first studied in the context of Z2 spin liquid in 1991). The toric code can also be considered to be a Z2 lattice gauge theory in a particular limit. It was introduced by Alexei Kitaev.
In quantum many-body physics, topological degeneracy is a phenomenon in which the ground state of a gapped many-body Hamiltonian becomes degenerate in the limit of large system size such that the degeneracy cannot be lifted by any local perturbations.
Giovanni Vignale is an Italian American physicist and Professor of Physics at the University of Missouri. Vignale is known for his work on density functional theory - a theoretical approach to the quantum many-body problem - and for several contributions to many-particle physics and spintronics. He is also the author of a monograph on the "Quantum Theory of the Electron Liquid" and a book entitled "The Beautiful Invisible - Creativity, imagination, and theoretical physics".
The Strictly-Correlated-Electrons (SCE) density functional theory approach, originally proposed by Michael Seidl, is a formulation of density functional theory, alternative to the widely used Kohn-Sham DFT, especially aimed at the study of strongly-correlated systems. The essential difference between the two approaches is the choice of the auxiliary system. In Kohn-Sham DFT this system is composed by non-interacting electrons, for which the kinetic energy can be calculated exactly and the interaction term has to be approximated. In SCE DFT, instead, the starting point is totally the opposite one: the auxiliary system has infinite electronic correlation and zero kinetic energy.
Erio Tosatti is an Italian theoretical physicist active at the International School for Advanced Studies (SISSA), and at the Abdus Salam International Centre for Theoretical Physics (ICTP), both in Trieste, Italy. He is a broad-scope theorist who carried out research on a wide range of condensed matter physics phenomena. His early work dealt with optical properties, electron energy loss, theory of excitons and nonlocal dielectric response in solids, including layer crystals such as graphite and semiconductors; charge- and spin-density-waves; surface physics in all its aspects, particularly reconstruction, roughening and melting, also in clusters; the prediction the Berry phase in fullerene; the first calculated STM map of graphite, now a standard in the field; matter at extreme pressures: carbon, oxygen, hydrogen, CO2, iron at earth core conditions, water and ammonia at deep planetary conditions, pressure-induced insulator-metal transitions in layer compounds like MoS2. In nanophysics, he and his group predicted helical structures of metal nanowires; the spontaneous magnetism of metal nanocontacts, including the electronic circumstances for normal or ferromagnetic Kondo effect therein. His and his collaborator's theory of strongly correlated superconductivity was recently confirmed in compounds such as Cs3C60. Pioneering papers on quantum annealing are now basic to current developments in quantum computing. More recently he moved on to the theory of nanofriction, a field where he obtained the ERC Advanced Grant MODPHYSFRICT 2013–2019, and subsequently, as co-PI with an experimental group, another ERC Advanced Grant ULTRADISS 2019-2024. More details of his current and past research activity can be found here.
Bose–Einstein condensation of polaritons is a growing field in semiconductor optics research, which exhibits spontaneous coherence similar to a laser, but through a different mechanism. A continuous transition from polariton condensation to lasing can be made similar to that of the crossover from a Bose–Einstein condensate to a BCS state in the context of Fermi gases. Polariton condensation is sometimes called “lasing without inversion”.
