Masaru Fukunaga | Searcharxiv

arXiv2009

Fluxon-based generation of graph states in Josephson qubits

Graph states are a special kind of multiparticle entangled state with great potential for applications in quantum information technologies, especially in measurement-based quantum computers. These states cause significant reductions of the number of qubits needed for a given computation, leading to shorter execution time. Here we propose a simple scheme for generating such graph states by using special gate operations, i.e., control-phase and swap gate operations, inherent in superconducting quantum nanocircuits.

cond-mat.supr-con↗

arXiv2004

A model independent determination of $|V_{ub}|$ using the global $q^2$ dependence of the dispersive bounds on the $B\toπlν$ form factors

We propose a method to determine the CKM matrix element $|V_{ub}|$ using the global $q^2$ dependence of the dispersive bound on the form factors for $B\to πlν$ decay. Since the lattice calculation of the $B\to πlν$ form factor is limited to the large $q^2$ regime, only the experimental data in a limited kinematic range can be used in a conventional method. In our new method which exploits the statistical distributions of the dispersive bound proposed by Lellouch, we can utilize the information of the global $q^2$ dependence for all kinematic range. As a feasibility study we determine $|V_{ub}|$ by combining the form factors from quenched lattice QCD, the dispersive bounds, and the experimental data by CLEO. We show that the accuracy of $|V_{ub}|$ can be improved by our method.

hep-lat↗