Dirac quantum time mirror
  Both metaphysical and practical considerations related to time inversion have intrigued scientists for generations. Physicists have strived to devise and implement time-inversion protocols, in particular different forms of "time mirrors" for classical waves. Here we propose an instantaneous time mirror for quantum systems, i.e., a controlled time discontinuity generating wave function echoes with high fidelities. This concept exploits coherent particle-hole oscillations in a Dirac spectrum in order to achieve population reversal, and can be implemented in systems such as (real or artificial) graphene. 
Phillipp Reck, Cosimo Gorini, Arseni Goussev, Viktor Krueckl, Mathias   Fink, Klaus Richter
cond-mat.mes-hall quant-ph