Berlin 2014 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 59: Quantum information: Quantum computers and communication I
Q 59.8: Vortrag
Freitag, 21. März 2014, 12:15–12:30, DO26 207
Decrease in query complexity for quantum computers with superposition of circuits — •Mateus Araújo1,2, Fabio Costa1,2, and Časlav Brukner1,2 — 1Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria — 2Institute of Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
The standard model for quantum computation assumes that quantum gates are applied in a specific order. One can relax this assumption by allowing a control quantum system to switch the order in which the gates are applied. This provides for a more general kind of quantum computing, that allows for transformations on black box quantum gates that are impossible with fixed circuits [1]. Here we show that this model of quantum computing is physically realizable, by proposing an interferometric setup which can implement such a quantum control of the order of the operations. We also show that this new resource provides a reduction in computational complexity: we propose a problem that can be solved using O(n) queries to the black box unitaries, whereas the best known quantum algorithm with fixed order between the gates requires O(n2) queries.
[1] G. Chiribella, G. M. D’Ariano, P. Perinotti, and B. Valiron, “Quantum computations without definite causal structure”, Phys. Rev. A 88, 022318 (2013),