University of Basel  > Condensed Matter Theory

Luca Chirolli

Address:  Office 4.6
Department of Physics and Astronomy
University of Basel
Klingelbergstrasse 82
CH-4056 Basel, Switzerland
phone (office):  +41 61 267 3744 
fax:  +41 61 267 1349


Laurea in Fisica Teorica, UniversitÓ di Bologna, Italia, (2005)

Full control of qubit rotations in a voltage-biased superconducting flux qubit
Luca Chirolli, Guido Burkard
Phys. Rev. B 74, 174510 (2006), cond-mat/0606587,

We study a voltage-controlled version of the superconducting flux qubit [Chiorescu \textit{et al.}, Science 299, 1869 (2003)] and show that full control of qubit rotations on the entire Bloch sphere can be achieved. Circuit graph theory is used to study a setup where voltage sources are attached to the two superconducting islands formed between the three Josephson junctions in the flux qubit. Applying a voltage allows qubit rotations about the y axis, in addition to pure $x$ and $z$ rotations obtained in the absence of applied voltages. The orientation and magnitude of the rotation axis on the Bloch sphere can be tuned by the gate voltages, the external magnetic flux, and the ratio $\alpha$ between the Josephson energies via a flux-tunable junction. We compare the single-qubit control in the known regime a<1 with the unexplored range a>1 and estimate the decoherence due to voltage fluctuations.

Voltage control in a three-junction flux qubit
DPG - Dresden, Germany, March 2006.