PT-symmetry breaking in resonant tunneling heterostructures
  We present fermionic model based on symmetric resonant tunneling heterostructure, which demonstrates spontaneous symmetry breaking in respect to combined operations of space inversion (P) and time reversal (T). PT-symmetry breaking manifests itself in resonance coalescence (collapse of resonances). We show that resonant energies are determined by eigenvalues of auxiliary pseudo-Hermitian PT-invariant Hamiltonian. 
A.A. Gorbatsevich and N.M. Shubin
cond-mat.mes-hall cond-mat.other