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  • Electronic Resource  (4)
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  • 2000-2004  (4)
  • 2004
  • 2003  (4)
  • PACS. 71.10.-w Theories and models of many-electron systems – 73.21.La Quantum dots – 73.20.Qt Electron solids  (2)
  • PACS. 71.35.-y Excitons and related phenomena  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Andreev-Lifshitz supersolid revisited for a few electrons on a square lattice. I (2003)
    Springer
    The European physical journal 31 (2003), S. 401-412 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 71.10.-w Theories and models of many-electron systems – 73.21.La Quantum dots – 73.20.Qt Electron solids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: In 1969, Andreev and Lifshitz have conjectured the existence of a supersolid phase taking place at zero temperature between the quantum liquid and the solid. In this and a succeeding paper, we re-visit this issue for a few polarized electrons (spinless fermions) interacting via a U/r Coulomb repulsion on a two dimensional L×L square lattice with periodic boundary conditions and nearest neighbor hopping t. This paper is restricted to the magic number of particles N = 4 for which a square Wigner molecule is formed when U increases and to the size L = 6 suitable for exact numerical diagonalizations. When the Coulomb energy to kinetic energy ratio r s = UL/(2t ) reaches a value r s F ≈ 10, there is a level crossing between ground states of different momenta. Above r s F, the mesoscopic crystallization proceeds through an intermediate regime ( r s F 〈 r s 〈 r s W ≈ 28) where unpaired fermions with a reduced Fermi energy co-exist with a strongly paired, nearly solid assembly. We suggest that this is the mesoscopic trace of the supersolid proposed by Andreev and Lifshitz. When a random substrate is included, the level crossing at r s F is avoided and gives rise to a lower threshold r s F(W) 〈 r s F where two usual approximations break down: the Wigner surmise for the distribution of the first energy excitation and the Hartree-Fock approximation for the ground state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2003-00048-0
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  • 2
    Electronic Resource
    Electronic Resource
    Density expansion of the energy of N close-to-boson excitons (2003)
    Springer
    The European physical journal 31 (2003), S. 517-523 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 71.35.-y Excitons and related phenomena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Pauli exclusion between the carriers of N excitons induces novel many-body effects, quite different from the ones generated by Coulomb interaction. Using our commutation technique for interacting close-to-boson particles, we here calculate the Hamiltonian expectation value in the N-ground-state-exciton state. Coulomb interaction enters this quantity at first order only by construction; nevertheless, due to Pauli exclusion, subtle many-body effects take place, which give rise to terms in (Na x 3/ )n with n ≥ 2. An exact procedure to get these density dependent terms is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2003-00061-3
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  • 3
    Electronic Resource
    Electronic Resource
    Trions in first and second quantizations (2003)
    Springer
    The European physical journal 33 (2003), S. 311-320 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 71.35.-y Excitons and related phenomena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We reconsider the semiconductor trions from scratch. We first determine the very many “reasonable” ways to write the trions in first quantization. We then select the forms which are easy to relate to physical pictures. In a second part, we derive the corresponding creation operators in second quantization. We pay particular attention to the expression of the X- trion in terms of exciton and free-electron, as it is the one adapted to future works on many-body effects with trions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2003-00171-x
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  • 4
    Electronic Resource
    Electronic Resource
    Andreev-Lifshitz supersolid revisited for a few electrons on a square lattice II (2003)
    Springer
    The European physical journal 33 (2003), S. 87-101 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 71.10.-w Theories and models of many-electron systems – 73.21.La Quantum dots – 73.20.Qt Electron solids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: In this second paper, using N = 3 polarized electrons (spinless fermions) interacting via a U/r Coulomb repulsion on a two dimensional L×L square lattice with periodic boundary conditions and nearest neighbor hopping t, we show that a single unpaired fermion can co-exist with a correlated two particle Wigner molecule for intermediate values of the Coulomb energy to kinetic energy ratio r s = UL/(2t ). This supports in an ultimate mesoscopic limit a possibility proposed by Andreev and Lifshitz for the thermodynamic limit: a quantum crystal may have delocalized defects without melting, the number of sites of the crystalline array being smaller than the total number of particles. When L = 6, the ground state exhibits four regimes as rs increases: a Hartree-Fock regime, a first supersolid regime where a correlated pair co-exists with a third fully delocalized particle, a second supersolid regime where the third particle is partly delocalized, and eventually a correlated lattice regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2003-00145-0
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    Paper (German National Licenses)
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