Mainz 2017 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 42: Quantum Effects

Q 42.4: Talk

Thursday, March 9, 2017, 11:45–12:00, P 4

Non-Markovianity and the physics of memory — •Nina Megier¹, Dariusz Chruściński², Jyrki Piilo³, and Walter T. Strunz¹ — ¹TU Dresden — ²Nicolaus Copernicus University in Toruń — ³University of Turku

In our work we analyse a family of qubit CPT maps, characterized by a point within a parameter triangle. The corresponding generator of the dynamics may contain exactly one negative decoherence rate. Based on the concept of CP-divisibility such evolution is classified as non-Markovian. Nonetheless, the dynamical map can be written as a random unitary evolution or a convex combination of Markovian semigroups. Remarkably, we find a realisation based on a classical Markov process, where the probabilities are governed by a classical Pauli master equation. Such a classical Markov representation exists also for a non-P-divisible dynamics of an extended two qubit system. In both cases a description with a bipartite GKSL equation, where the ancilla state is frozen, is possible, too. These realisations show that actually there is no room for physical memory effects. Therefore, both non-CP-divisibility, but also the weaker non-P-divisibility, are sometimes questionable indicators for non-Markovianity. A reduced description may not suffice to study the physics of memory and information flow.