Baryons and Skyrmions in QCD with Quarks in Higher Representations

We study the baryonic sector of QCD with quarks in the two index symmetric or antisymmetric representation. The minimal gauge invariant state that carries baryon number cannot be identified with the Skyrmion of the low energy chiral effective Lagrangian. Mass, statistics and baryon number do not match. We carefully investigate the properties of the minimal baryon in the large N limit and we find that it is unstable under formation of bound states with higher baryonic number. These states match exactly with the properties of the Skyrmion of the effective Lagrangian.Comment: 23 pages, 13 figures. v2: minor changes. v3: corrected a mistake and some typos. v4: modifyed the part about the stability of the Skyrmio

A PDE-constrained optimization formulation for discrete fracture network flows

We investigate a new numerical approach for the computation of the 3D flow in a discrete fracture network that does not require a conforming discretization of partial differential equations on complex 3D systems of planar fractures. The discretization within each fracture is performed independently of the discretization of the other fractures and of their intersections. Independent meshing process within each fracture is a very important issue for practical large scale simulations making easier mesh generation. Some numerical simulations are given to show the viability of the method. The resulting approach can be naturally parallelized for dealing with systems with a huge number of fractures

Non-Hermitian shortcut to stimulated Raman adiabatic passage

We propose a non-Hermitian generalization of stimulated Raman adiabatic passage (STIRAP), which allows one to increase speed and fidelity of the adiabatic passage. This is done by adding balanced imaginary (gain/loss) terms in the diagonal (bare energy) terms of the Hamiltonian and choosing them such that they cancel exactly the nonadiabatic couplings, providing in this way an effective shortcut to adiabaticity. Remarkably, for a STIRAP using delayed Gaussian-shaped pulses in the counter-intuitive scheme the imaginary terms of the Hamiltonian turn out to be time independent. A possible physical realization of non-Hermitian STIRAP, based on light transfer in three evanescently-coupled optical waveguides, is proposed.Comment: 7 pages, 4 figure

Barkhausen noise in soft amorphous magnetic materials under applied stress

We report experimental measurements of Barkhausen noise on Fe_{64}Co_{21}B_{15} amorphous alloy under tensile stress. We interpret the scaling behavior of the noise distributions in terms of the depinning transition of the domain walls. We show that stress induced anisotropy enhance the effect of short-range elastic interactions that dominate over long-range dipolar interactions. The universality class is thus different from the one usually observed in Barkhausen noise measurements and is characterized by the exponents \tau = 1.3 and \alpha = 1.5, for the decay of the distributions of jump sizes and durations.Comment: 6 pages, 3 .eps figures. Submitted to the 43rd Magnetism and Magnetic Materials Conference (J. Appl. Phys.

A Stabilization Mechanism of Zirconia Based on Oxygen Vacancies Only

The microscopic mechanism leading to stabilization of cubic and tetragonal forms of zirconia (ZrO$_2$) is analyzed by means of a self-consistent tight-binding model. Using this model, energies and structures of zirconia containing different vacancy concentrations are calculated, equivalent in concentration to the charge compensating vacancies associated with dissolved yttria (Y$_2$O$_3$) in the tetragonal and cubic phase fields (3.2 and 14.4% mol respectively). The model is shown to predict the large relaxations around an oxygen vacancy, and the clustering of vacancies along the $$ directions, in good agreement with experiments and first principles calculations. The vacancies alone are shown to explain the stabilization of cubic zirconia, and the mechanism is analyzed.Comment: 19 pages, 6 figures. To be published in J. Am. Ceram. So

Quantum simulation of the Riemann-Hurwitz zeta function

We propose a simple realization of a quantum simulator of the Riemann-Hurwitz (RH) \zeta\ function based on a truncation of its Dirichlet representation. We synthesize a nearest-neighbour-interaction Hamiltonian, satisfying the property that the temporal evolution of the autocorrelation function of an initial bare state of the Hamiltonian reproduces the RH function along the line \sigma+i \omega t of the complex plane, with \sigma>1. The tight-binding Hamiltonian with engineered hopping rates and site energies can be implemented in a variety of physical systems, including trapped ion systems and optical waveguide arrays. The proposed method is scalable, which means that the simulation can be in principle arbitrarily accurate. Practical limitations of the suggested scheme, arising from a finite number of lattice sites N and from decoherence, are briefly discussed.Comment: 6 pages, 3 figure

Exact solution of time-dependent Lindblad equations with closed algebras

Time-dependent Lindblad master equations have important applications in areas ranging from quantum thermodynamics to dissipative quantum computing. In this paper we outline a general method for writing down exact solutions of time-dependent Lindblad equations whose superoperators form closed algebras. We focus on the particular case of a single qubit and study the exact solution generated by both coherent and incoherent mechanisms. We also show that if the time-dependence is periodic, the problem may be recast in terms of Floquet theory. As an application, we give an exact solution for a two-levels quantum heat engine operating in a finite-time.Comment: 15 pages, 12 figure