BIRS Workshop Lecture Videos

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BIRS Workshop Lecture Videos

Sublinear Coherence distillation and a no-broadcasting theorem for coherence and asymmetry Marvian, Iman


In this talk I discuss coherence distillation under Time translation Invariant operations. I show that although for a generic mixed state the distillation rate is zero, it is still possible to distill a sub-linear number of a pure coherent state, with fidelity approaching one, provided that we can consume asymptotically many copies of the mixed state. Furthermore, for a generic mixed input state, there is a tradeoff between the maximum achievable yield and the fidelity with pure coherent states. Interestingly, it turns out that Petz-Renyi relative entropy for alpha=2 gives a tight bound on the maximum achievable fidelity. Furthermore, coherence distillation provides an operational explanation for the violation of the monotonicity of Petz-Renyi relative entropy for the parameter range alpha>2. Finally, I talk about the limitations of measure-and-prepare (entanglement-breaking) processes for coherence distillation. If time allows, I also briefly discuss a new no-broadcasting theorem for coherence and asymmetry. The no-go theorem states that if two initially uncorrelated systems interact by symmetric dynamics and asymmetry is created at one subsystem, then the asymmetry of the other subsystem must be reduced. I also present a quantitative relation describing the tradeoff between the subsystems.

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