Search results for "Functional analysis"
showing 10 items of 1059 documents
The Isomeric 9/2+and the Lowest 7/2-State in the Weakly Deformed N = 89 Nuclei
1979
The decays of the isomeric 9/2+ states which have been produced by (d, pγ) and (3He, xnγ) reactions, have been investigated in three N = 89 nuclei. The half-lives have been determined to be 5.1 ± 0.3 ns in 149Nd and 3.5 ± 0.4 μs in 153Gd. In 155Dy a 5.5 ns half-life was found, but we were unable to assign it to the 9/2+ state. The calculated E1 transition probability from the 9/2+ state has been used as a probe in suggesting the following main components for the lowest-lying 7/2- state: 7/2 5/2-[523] in 149Nd, 7/2 3/2-[521] in 153Gd and 7/2 3/2-[521] in 155Dy. The corresponding 7/2- state in 151Sm is proposed to be 7/2{1}3/2-[532] + 5/2-[523]{1}. All calculations have been performed using a…
Near-deterministic creation of universal cluster states with probabilistic Bell measurements and three-qubit resource states
2015
We develop a scheme for generating a universal qubit cluster state using probabilistic Bell measurements without the need for feed-forward. Borrowing ideas from percolation theory, we numerically show that using unambiguous Bell measurements that succeed with 75% success probability one could build a cluster state with an underlying pyrochlore geometry such that the probability of having a spanning cluster approaches unity in the limit of infinite lattice size. The initial resources required for the generation of a universal state in our protocol are three-qubit cluster states that are within experimental reach and are a minimal resource for a Bell-measurement-based percolation proposal. Si…
Monte-Carlo Study of Pure-Phase Cumulants of 2D q-State Potts Models
1997
We performed Monte Carlo simulations of the two-dimensional q-state Potts model with q=10, 15, and 20 to study the energy and magnetization cumulants in the ordered and disordered phase at the first-order transition point $\beta_t$. By using very large systems of size 300 x 300, 120 x 120, and 80 x 80 for q=10, 15, and 20, respectively, our numerical estimates provide practically (up to unavoidable, but very small statistical errors) exact results which can serve as a useful test of recent resummed large-q expansions for the energy cumulants by Bhattacharya `et al.' [J. Phys. I (France) 7 (1997) 81]. Up to the third order cumulant and down to q=10 we obtain very good agreement, and also the…
Efficient spin torques in antiferromagnetic CoO/Pt quantified by comparing field- and current- induced switching
2020
Comment: 16 pages (manuscript and supplementary), 12 figures
Effects of nonlinear sweep in the Landau-Zener-Stueckelberg effect
2002
We study the Landau-Zener-Stueckelberg (LZS) effect for a two-level system with a time-dependent nonlinear bias field (the sweep function) W(t). Our main concern is to investigate the influence of the nonlinearity of W(t) on the probability P to remain in the initial state. The dimensionless quantity epsilon = pi Delta ^2/(2 hbar v) depends on the coupling Delta of both levels and on the sweep rate v. For fast sweep rates, i.e., epsilon << l and monotonic, analytic sweep functions linearizable in the vicinity of the resonance we find the transition probability 1-P ~= epsilon (1+a), where a>0 is the correction to the LSZ result due to the nonlinearity of the sweep. Further increase …
Inverse problem for the Landau-Zener effect
2002
We consider the inverse Landau-Zener problem which consists in finding the energy-sweep functions W(t)=E1(t)-E2(t) resulting in the required time dependences of the level populations for a two-level system crossing the resonance one or more times during the sweep. We find sweep functions of particular forms that let manipulate the system in a required way, including complete switching from the state 1 to the state 2 and preparing the system at the exact ground and excited states at resonance.
Theory of radiative recombination from the metastable excited states of quantum dots
1998
The radiative recombination of an exciton ~electron-hole pair! confined in a semiconductor quantum dot is studied within a general model based on the effective-mass approximation. The dependence of the photoluminescence spectrum on the size of the dot and the magnetic field describe well a series of recent experimental results. In particular, a characteristic splitting of the main photoluminescence peak into a doublet or triplet is observed at the critical size and magnetic field, as a consequence of the appearance of metastable states in the exciton spectrum. @S0163-1829~98!06915-X#
Anomalous magneto-transport in disordered structures: classical edge-state percolation
2015
By event-driven molecular dynamics simulations we investigate magneto-transport in a two-dimensional model with randomly distributed scatterers close to the field-induced localization transition. This transition is generated by percolating skipping orbits along the edges of obstacle clusters. The dynamic exponents differ significantly from those of the conventional transport problem on percolating systems, thus establishing a new dynamic universality class. This difference is tentatively attributed to a weak-link scenario, which emerges naturally due to barely overlapping edge trajectories. We make predictions for the frequency-dependent conductivity and discuss implications for active coll…
Identification of Néel Vector Orientation in Antiferromagnetic Domains Switched by Currents in NiO/Pt Thin Films
2021
Understanding the electrical manipulation of the antiferromagnetic order is a crucial aspect to enable the design of antiferromagnetic devices working at THz frequencies. Focusing on collinear insulating antiferromagnetic $\mathrm{Ni}\mathrm{O}/\mathrm{Pt}$ thin films as a materials platform, we identify the crystallographic orientation of the domains that can be switched by currents and quantify the N\'eel-vector direction changes. We demonstrate electrical switching between different T domains by current pulses, finding that the N\'eel-vector orientation in these domains is along [$\ifmmode\pm\else\textpm\fi{}5$ $\ifmmode\pm\else\textpm\fi{}5$ 19], different compared to the bulk $⟨112⟩$ d…
Size-consistent self-consistent configuration interaction from a complete active space : Excited states
1998
The self-consistent size consistent on a complete active space singly and doubly configuration interaction (SC)2CAS-SDCI method is applied to excited states. The (SC)2 correction is performed on a closed shell state, and the excited states are obtained by diagonalization of the dressed matrix. A theoretical justification of the transferability of the improvement concerning the dressing state to all roots of the matrix is presented. The method is tested by three tests on the spectrum of small molecules. sanchezm@uv.es ; nebot@uv.es