Systems with balanced loss and gain : PT-symmetric lattices (how do high-school students publish in Physical Review?)

A non-Hermitian Hamiltonian that is invariant under the combined parity and time-reversal operations is called PT-symmetric. It has a purely real eigenvalues over a range of parameters, and the emergence of complex eigenvalues is called PT-symmetry breaking. In the past three years, it has become clear that far from being a mathematical curiosity, PT-symmetric Hamiltonians model diverse systems - optical waveguides, LCR circuits, electron 
gases - with equal loss and gain. Here, I will discuss the properties of a tight-biding lattice with balanced source and sink impurities. I will show that the PT-symmetry breaking is 
accompanied by dramatic, tunable signatures in observables such as intensity or momentum. I will conclude with a brief discussion regarding the involvement of high-school and undergraduate students in this research.