TY - JOUR

T1 - Quantum Monte Carlo simulations of exciton condensates

AU - Shumway, J.

AU - Ceperley, D. M.

N1 - Funding Information:
We thank Jim Mitroy for his comments to us about scattering calculations and the use of effective range theory. Work supported by NSF grants DMR 98-02373, DGE 93-54978, DMR02-39819 and computer resources at NCSA.

PY - 2005/4

Y1 - 2005/4

N2 - We have studied scattering states and thermodynamic properties of electron-hole systems. Starting from the constituent electrons and holes and Coulomb interactions, we have used quantum Monte Carlo simulation techniques to sample properties of wavefunctions and thermal density matrices. We have studied three types of systems: (1) the scattering of two excitons, with full-quantum treatment of the four constituent particles, (2) the thermodynamic equilibrium of 14 electron-hole pairs having two spin states for each particle, which form excitons and biexcitons at low temperatures, and (3) the thermodynamic equilibrium of 27 spin-polarized electron-hole pairs, which form a dilute exciton gas that undergoes Bose condensation at low temperatures. We compare our results with predictions of the Saha equation for exciton and biexciton formation, and Bogoliubov theory for the energy of the dilute Bose gas of excitons. We also discuss the outlook for future quantum Monte Carlo simulations on these systems.

AB - We have studied scattering states and thermodynamic properties of electron-hole systems. Starting from the constituent electrons and holes and Coulomb interactions, we have used quantum Monte Carlo simulation techniques to sample properties of wavefunctions and thermal density matrices. We have studied three types of systems: (1) the scattering of two excitons, with full-quantum treatment of the four constituent particles, (2) the thermodynamic equilibrium of 14 electron-hole pairs having two spin states for each particle, which form excitons and biexcitons at low temperatures, and (3) the thermodynamic equilibrium of 27 spin-polarized electron-hole pairs, which form a dilute exciton gas that undergoes Bose condensation at low temperatures. We compare our results with predictions of the Saha equation for exciton and biexciton formation, and Bogoliubov theory for the energy of the dilute Bose gas of excitons. We also discuss the outlook for future quantum Monte Carlo simulations on these systems.

KW - A. Semiconductors

KW - D. Bose-Einstein condensation

KW - D. Excitons

KW - E. Computer simulations

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U2 - 10.1016/j.ssc.2004.11.046

DO - 10.1016/j.ssc.2004.11.046

M3 - Article

AN - SCOPUS:14644429769

SN - 0038-1098

VL - 134

SP - 19

EP - 22

JO - Solid State Communications

JF - Solid State Communications

IS - 1-2

ER -