QUANTUM MONTE CARLO SIMULATIONS

1
QUANTUM MONTE CARLO SIMULATIONS
NO SMALL PARAMETER NEAR UNITARITY
ISSUES BEHAVIOR AS A FUNCTION OF T and

• THERMODYNAMICS
• ORDER PARAMETER
• SINGLE PARTICLE GAP AND COLLECTIVE EXCITATIONS
• RESPONSE FUNCTIONS e.g. SUPERFLUID DENSITY
• REAL TIME DYNAMICS

2
QMC T0
IMPROVEMENT BY DIFFUSION MONTE CARLO
FIXED NODE APPROXIMATION
E(T0,g) OP(T0,g)
Giorgini et. al. Pandharipande et. al.
3
QMC
COHERENT STATE PATH INTEGRAL
Introduce auxilliary fields to deal with quartic
interaction term
For attractive Hubbard model on a lattice at any
filling product of detgt0 (if auxilliary field is
coupled to density) NO SIGN PROBLEM Hirsch PRB
28, 4059 (1983)
E(T,g)
Bulgac et. al.
Finite size scaling to extract singularity