Jena 2013 – wissenschaftliches Programm
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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik
MP 2: Quanteninformation
MP 2.1: Vortrag
Dienstag, 26. Februar 2013, 14:00–14:25, HS 8
The Magic Power of Combining Coherent Control with Switchable Markovian Noise Amplitudes — •Thomas Schulte-Herbrüggen1 and Ville Bergholm2 — 1Dept. Chem., TU-München — 2Institute for Scientific Interchange Foundation
Adding bang-bang switchable noise on a single qubit (out of a total of n) on top of unitary control seems magic: For amplitude-damping noise (non-unital) this simple add-on suffices for acting transitively on the set of all density operators. So one can transform any initial state into any desired target state. For bit-flip noise (unital), the add-on allows for reaching any target state majorised by the initial state [1].
In the Lie-semigroup framework of Markovian open systems, we also show that for state transfer our Markovian open-loop scheme [1] is as powerful as measurement-based closed-loop control schemes designed to embrace non-Markovian evolution [2].
We have extended our open-loop optimal control algorithm (dynamo) by incoherent control so that these unprecedented reachable sets can systematically be exploited in experiments [1]. As illustrated for an ion trap experimental setting, open-loop control with noise switching can thus simplify the more complicated measurement-based closed-loop feedback schemes [2,3,4] requiring a resettable ancilla qubit.
[1] V. Bergholm and T. Schulte-Herbrüggen, arXiv/1206.4945 (2012)
[2] S. Lloyd and L. Viola, Phys. Rev. A 65, 010101 (2001)
[3] J. Barreiro et al., Nature 470, 486 (2011)
[4] P. Schindler et al., arXiv/1212.2418 (2012)