Eternal non-Markovianity: from random unitary to Markov chain realisations
: Nina Megier, Dariusz Chruściński, Jyrki Piilo, Walter T. Strunz
Publisher: NATURE PUBLISHING GROUP
: 2017
: Scientific Reports
: SCIENTIFIC REPORTS
: SCI REP-UK
: 6379
: 7
: 11
: 2045-2322
DOI: https://doi.org/10.1038/s41598-017-06059-5(external)
: https://research.utu.fi/converis/portal/detail/Publication/27562715(external)
The theoretical description of quantum dynamics in an intriguing way does not necessarily imply the underlying dynamics is indeed intriguing. Here we show how a known very interesting master equation with an always negative decay rate [eternal non-Markovianity (ENM)] arises from simple stochastic Schrodinger dynamics (random unitary dynamics). Equivalently, it may be seen as arising from a mixture of Markov (semi-group) open system dynamics. Both these approaches lead to a more general family of CPT maps, characterized by a point within a parameter triangle. Our results show how ENM quantum dynamics can be realised easily in the laboratory. Moreover, we find a quantum time-continuously measured (quantum trajectory) realisation of the dynamics of the ENM master equation based on unitary transformations and projective measurements in an extended Hilbert space, guided by a classical Markov process. Furthermore, a Gorini-Kossakowski-Sudarshan-Lindblad (GKSL) representation of the dynamics in an extended Hilbert space can be found, with a remarkable property: there is no dynamics in the ancilla state. Finally, analogous constructions for two qubits extend these results from non-CP-divisible to non-P-divisible dynamics.
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