Regensburg 2004 – scientific programme
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TT: Tiefe Temperaturen
TT 17: Postersitzung II: Transport, Quantenkoh
ärenz, Quantenflüssigkeiten
TT 17.18: Poster
Tuesday, March 9, 2004, 14:30–19:00, Poster A
Compensation of telegraph noise decoherence by means of bang-bang control — •Henryk Gutmann1, William Kaminsky2, Seth Lloyd3, and Frank Wilhelm1 — 1Sektion Physik and CeNS, LMU, 80333 München — 2Department of Physics, MIT, Cambridge, Mass. 02139 — 3Department of Mechanical Engineering, MIT, Cambridge, Mass. 02139
With growing success in isolating solid-state qubits from external noise sources the origins of decoherence inherent to the material start to play a relevant role. Prominent examples were charged impurities in the disordered substrate of a Josephson qubit which produce typically telegraph noise. In order to demonstrate the possibility of the active suppression of the disturbance from a single fluctuator, we theoretically implement an elementary bang-bang control protocol. We numerically simulate the appearing random walk on the Bloch sphere with and without bang-bang control and compare it with analytical results found by use of appropriate Langevin equations in the long-time limit. Hereby we find out, that the bang-bang control mechanism mostly compensates the slow noise, which indicates, how the influence of 1/f-noise ubiquitous to the solid-state world could be reduced. We also derive two generic and analytically solvable random walk models to describe imperfect pulses and evaluate the impact of these aberrations on the qubit.