Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 18: TR: Quantum Coherence and Quantum Information Systems 1

TT 18.1: Talk

Tuesday, March 23, 2010, 14:00–14:15, H21

Optimized Pulse Sequences for the Suppression of Decoherence in Quantum Information — •Stefano Pasini and Götz S. Uhrig — Lehrstuhl für Theoretische Physik I, TU Dortmund, 44221 Dortmund

The dynamical decoupling (DD) aims at suppressing the decoherence by means of coherent control pulses. Even if devices exist where instantaneous pulses are an adequate approximation, experimentally a finite duration τ_p and a bounded amplitude are inevitable. They are the cause of additional errors which can be corrected by designing the pulse shape appropriately. The new pulse has the overall effect of an ideal, instantaneous pulse with the advantage of decoupling the spin (or qubit) from the bath up to the order O(τ_p³) [1]. The limitation of the no-go theorem for π pulses [2] is avoided. Hence, the Uhrig sequence (UDD) [3], originally thought for ideal π pulses, works also for bounded control Hamiltonians [4]. Numerical simulations show that concatenated sequences of real pulses are effective against general decoherence.

[1] S. Pasini, P. Karbach, C. Raas and G.S. Uhrig, Phys. Rev. A 80, 022328 (2009)

[2] S. Pasini, T. Fischer, P. Karbach and G.S. Uhrig, Phys. Rev. A 77, 032315 (2008)

[3] G.S. Uhrig, Phys. Rev. Lett. 98, 100504 (2007)

[4] G.S. Uhrig and S. Pasini, arXiv:0906.3605