**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 |

e-mail: |
Luca.Chirolli@unibas.ch |

phone (office): |
+41 61 267 3744 |

fax: |
+41 61 267 1349 |

**CV**

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

**Publications**

**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.

**Talks**

**Voltage control in a three-junction flux qubit**

DPG - Dresden, Germany, March 2006.