1 research outputs found
Ground state fidelity and quantum phase transitions in free Fermi systems
We compute the fidelity between the ground states of general quadratic
fermionic hamiltonians and analyze its connections with quantum phase
transitions. Each of these systems is characterized by a real
matrix whose polar decomposition, into a non-negative and a unitary
, contains all the relevant ground state (GS) information. The boundaries
between different regions in the GS phase diagram are given by the points of,
possibly asymptotic, singularity of . This latter in turn implies a
critical drop of the fidelity function. We present general results as well as
their exemplification by a model of fermions on a totally connected graph.Comment: 4 pages, 2 figure