Séminaire spécialisé proposé par Geneviève Fleury
Both metaphysical and practical considerations intrigued generations of scientists to devise and implement time-inversion protocols – in particular the Hahn echo , different forms of “time mirrors” for classical waves (see e.g. ), and recently an instantaneous time mirror for water waves . With our proposal for an instantaneous Quantum Time Mirror , we showed the possibility to extend the family of time reversal protocols to continuous quantum systems, more precisely to wave packets in Dirac-cone systems, by changing the propagation direction with a short, time-dependent pulse.
As examples, we discuss the effect on the Quantum Time Mirror of both, a static, out-of-plane magnetic field, which breaks time-reversal symmetry, and band structures other than the Dirac cone, e.g. the valence and conduction bands in direct gap semi-conductors. Moreover, we show that applying the time-dependent pulse periodically, we can devise effectively a discrete quantum walk with tunable "coin" parameters.
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 P. Reck, et al., Phys. Rev. B 95, 165421 (2017)