Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:cond-mat/0409304 · International Journal of Modern Physics B

SUPERCONDUCTING COHERENT STATES FOR AN EXTENDED HUBBARD MODEL

Fethi Madouri, Y. Hassouni, M. El Baz

Published Oct 30, 2003• 0 citations
arXivHTMLPDF

Abstract

An extended Hubbard model with phonons is considered. q-coherent states relative to the superconducting quantum symmetry of the model are constructed and their properties studied. It is shown that they can have energy expectation lower than eigenstates constructed via conventional processes and that they exhibit ODLRO.
DOI
10.1142/s0217979203023094

Related papers

Coherent pairing states for the Hubbard model

A. I. Solomon, K. A. Penson

We consider the Hubbard model and its extensions on bipartite lattices. We define a dynamical group based on the -pairing operators introduced by Yang, and define coherent pairing states, which are combinations of eigenfunctions of -operators. These states permit exact calculations of numerous physical properties of the system, including energy, various fluctuations and correlation functions, including pairing off-diagonal long-range order to all orders. This approach is complementary to BCS, in that these are superconducting coherent states associated with the exact model, although they are not eigenstates of the Hamiltonian.

arXiv:cond-mat/9712228•Journal of Physics A Mathematical and General•May 8, 1998•6 citations

Quantum symmetries induced by phonons in the Hubbard model

Arianna Montorsi, Mario Rasetti

We show how the addition of a phonon field to the Hubbard model deforms the superconducting su(2) part of the global symmetry Lie algebra su(2)\ensuremath{\bigotimes}su(2)/${\mathit{openZ}}_{2}$, holding at half filling for the customary model, into a quantum [su(2)${]}_{\mathit{q}}$ symmetry, holding for a filling which depends on the electron-phonon interaction strength. Such symmetry originates in the feature that in the presence of phonons the hopping amplitude turns out to depend on the coupling strength. The states generated by resorting to this q symmetry exhibit both off-diagonal long-range order and pairing.

Physical Review Letters•Mar 14, 1994•13 citations

Eigenstate Possessing ODLRO for Hubbard Model

Song Zhi

Some eigenstates of Hubbard model are obtained. It is shown that the eigenstates possess off-diagonal-long-range-order (ODLRO).

Communications in Theoretical Physics•Oct 1, 1990•0 citations

SUPERCONDUCTING CLASSES IN THE EXTENDED HUBBARD MODEL

Masa-aki Ozaki, Eiji Miyai, Tomoaki Konishi +1 more

This paper describes group theoretical classification of superconducting states (SC) in the extended Hubbard model with on-site repulsion (U), nearest neighbor attraction (V) and nearest neighbour exchange interaction (J) on the two-dimensional square lattice using the mean field approach. By decomposing the pairing interaction into irreducible parts; A1g, B1g and Eu of D4h point symmetry, we have derived two singlet SCs (s-wave and d-wave) from A1g and B1g, eight triplet SCs from Eu. The first three types of triplet SC have pairing by electrons with antiparallel spin, the second two types have pairing by electrons with equal spin and the last three types are non-unitary and have pairing by only up-spin electrons. We showed that three non-unitary states have to be accompanied with a ferromagnetic order from the structure of the maximal little groups. We performed numerical studies for these SCs. For parameters and electron density favorable for the ferromagnetic order, a non-unitary SC coexistent with ferromagnetism is most stable.

International Journal of Modern Physics B•May 30, 1996•1 citation

On quantum groups in the Hubbard model with phonons

Bianca Letizia Cerchiai, Peter Schupp

The correct Hamiltonian for an extended Hubbard model with quantum group symmetry as introduced by Montorsi and Rasetti is derived for a D-dimensional lattice. It is shown that the superconducting holds as a true quantum symmetry only for D = 1 and that terms of higher order in the fermionic operators are needed in addition to phonons. A discussion of quantum symmetries in general is given in a formalism that should be readily accessible to non-Hopf algebraists.

arXiv:cond-mat/9510074•Journal of Physics A Mathematical and General•Feb 21, 1996•6 citations

OFF-DIAGONAL LONG RANGE ORDER IN AN ELECTRON-PHONON MODEL FOR HIGH- T c SUPERCONDUCTORS

M. Frick, I. Morgenstern, Wolfgang von der Linden

We study a model for high- T c superconductors describing both the strong electronic correlations and a coupling of the carriers to anharmonic phonons. The Projector Quantum Monte Carlo Scheme has been employed to investigate ground state properties. We analyze the superconducting properties of the model by directly addressing to the existence of Off-Diagonal Long Range Order (ODLRO). We review the numerical algorithm and discuss the possibility to observe ODLRO. In the presented model, we find ODLRO pointing towards superconductivity instead of the presence of strong electronic correlations. We discuss several features of the superconducting condensate.

International Journal of Modern Physics C•Feb 1, 1992•4 citations
We consider the Hubbard model and its extensions on bipartite lattices. We define a dynamical group based on the -pairing operators introduced by Yang, and define coherent pairing states, which are combinations of eigenfunctions of -operators. These states permit exact calculations of numerous physical properties of the system, including energy, various fluctuations and correlation functions, including pairing off-diagonal long-range order to all orders. This approach is complementary to BCS, in that these are superconducting coherent states associated with the exact model, although they are not eigenstates of the Hamiltonian.
We show how the addition of a phonon field to the Hubbard model deforms the superconducting su(2) part of the global symmetry Lie algebra su(2)\ensuremath{\bigotimes}su(2)/openZ2{\mathit{openZ}}_{2}openZ2​, holding at half filling for the customary model, into a quantum [su(2)]q{]}_{\mathit{q}}]q​ symmetry, holding for a filling which depends on the electron-phonon interaction strength. Such symmetry originates in the feature that in the presence of phonons the hopping amplitude turns out to depend on the coupling strength. The states generated by resorting to this q symmetry exhibit both off-diagonal long-range order and pairing.
This paper describes group theoretical classification of superconducting states (SC) in the extended Hubbard model with on-site repulsion (U), nearest neighbor attraction (V) and nearest neighbour exchange interaction (J) on the two-dimensional square lattice using the mean field approach. By decomposing the pairing interaction into irreducible parts; A1g, B1g and Eu of D4h point symmetry, we have derived two singlet SCs (s-wave and d-wave) from A1g and B1g, eight triplet SCs from Eu. The first three types of triplet SC have pairing by electrons with antiparallel spin, the second two types have pairing by electrons with equal spin and the last three types are non-unitary and have pairing by only up-spin electrons. We showed that three non-unitary states have to be accompanied with a ferromagnetic order from the structure of the maximal little groups. We performed numerical studies for these SCs. For parameters and electron density favorable for the ferromagnetic order, a non-unitary SC coexistent with ferromagnetism is most stable.
We study a model for high- T c superconductors describing both the strong electronic correlations and a coupling of the carriers to anharmonic phonons. The Projector Quantum Monte Carlo Scheme has been employed to investigate ground state properties. We analyze the superconducting properties of the model by directly addressing to the existence of Off-Diagonal Long Range Order (ODLRO). We review the numerical algorithm and discuss the possibility to observe ODLRO. In the presented model, we find ODLRO pointing towards superconductivity instead of the presence of strong electronic correlations. We discuss several features of the superconducting condensate.