Simple Non-Markovian Microscopic Models for the Depolarizing Channel of a Single Qubit

The archetypal one-qubit noisy channels ---depolarizing, phase-damping and amplitude-damping channels--- describe both Markovian and non-Markovian evolution. Simple microscopic models for the depolarizing channel, both classical and quantum, are considered. Microscopic models which describe phase damping and amplitude damping channels are briefly reviewed.Comment: 13 pages, 2 figures. Title corrected. Paper rewritten. Added references. Some typos and errors corrected. Author adde

Anomalies and O-plane charges in orientifolded brane tilings

We investigate orientifold of brane tilings. We clarify how the cancellations of gauge anomaly and Witten's anomaly are guaranteed by the conservation of the D5-brane charge. We also discuss the relation between brane tilings and the dual Calabi-Yau cones realized as the moduli spaces of gauge theories. Two types of flavor D5-branes in brane tilings and corresponding superpotentials of fundamental quark fields are proposed, and it is shown that the massless loci of these quarks in the moduli space correctly reproduce the worldvolume of flavor D7-branes in the Calabi-Yau cone dual to the fivebrane system.Comment: 46 pages, 19 figure

Switchable resonant coupling of flux qubits

We propose a coupling scheme, where two or more flux qubits with different eigenfrequencies share Josephson junctions with a coupler loop devoid of its own quantum dynamics. Switchable two-qubit coupling is realized by tuning the frequency of the AC magnetic flux through the coupler to a combination frequency of two of the qubits. The coupling allows any or all of the qubits to be simultaneously at the degeneracy point and can change sign.Comment: REVTeX 4, 4 pages, 2 figures, v2: reference added, v3: final version published in Phys. Rev.

Meta-Stable Brane Configuration and Gauged Flavor Symmetry

Starting from an N=1 supersymmetric electric gauge theory with the gauge group Sp(N_c) x SO(2N_c') with fundamentals for the first gauge group factor and a bifundamental, we apply Seiberg dual to the symplectic gauge group only and arrive at the N=1 supersymmetric dual magnetic gauge theory with dual matters including the gauge singlets and superpotential. By analyzing the F-term equations of the dual magnetic superpotential, we describe the intersecting brane configuration of type IIA string theory corresponding to the meta-stable nonsupersymmetric vacua of this gauge theory.Comment: 16 pp, 3 figures; stability analysis in page 7 and 8 added and the presentation improved; reduced bytes of figures and to appear in MPL

Brane Configurations for Nonsupersymmetric Meta-Stable Vacua in SQCD with Adjoint Matter

We present the configurations of intersecting branes in type IIA string theory corresponding to the meta-stable supersymmetry breaking vacua(hep-th/0608063) in the four-dimensional N=1 supersymmetric Yang-Mills theory coupled massive flavors with adjoint matter where the superpotential has three deformed terms.Comment: 15pp, 3 figures; The last two sentences in page 7 corrected; The last figure added;improved pages 10 and 11;figures corrected;the references to colors improved in the text and to appear in CQ