Berlin 2014 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 25: Quantum effects: Entanglement and decoherence II

Q 25.2: Talk

Tuesday, March 18, 2014, 14:15–14:30, DO24 1.101

A map for finding hidden quantum Markovian models — •Michael R. Hush, Igor Lesanovsky, and Juan P. Garrahan — University of Nottingham, Nottingham, NG7 2RD, UK

The aptly named master equation (ME) reigns over the analysis of open quantum systems. The Lindblad form - it is required to have - guarantees a density matrix that obeys it will always have a probabilistic (physical) interpretation. However many applications in nonequilibrium systems produce master equations that are not in Lindblad form, (NLME).

We solve this problem, by providing a framework to map NLME to a ME by the addition of an ancillary system. We demonstrate that the ancilla only need be a two level system.

We apply our result to two cases. We provide a way to physically access the dynamical large-deviation regime of open quantum systems, hopefully paving the way for experimental exploration of dynamical phase transition behaviour that has been predicted by theory.

Second we are able to prove a no-tracking theorem which states that given a quantum system undergoing a weak measurement it is impossible to track this system with a quantum system of the same size (even with the addition of an ancilla). This result has implications on what is achievable with regard to tracking, and quantum control in general.

Preprint available at: arXiv:1311.7394.