Search results for "Quantum physic"

Observer-based finite-time control for discrete fuzzy jump nonlinear systems with time delays

2013

This paper investigates the problem of observer-based finite-time H∞ control for a family of discrete jump nonlinear systems with time delays represented by Takagi-Sugeno (T-S) model. The main contribution of this paper is to design an observer-based finite-time H∞ controller such that the resulting closed-loop system is stochastic finite-time bounded and satisfies a prescribed H∞ disturbance attenuation level over the given finite-time interval. Sufficient criteria on stochastic finite-time H∞ stabilization via observer-based fuzzy state feedback are provided for the solvability of the problem, which can be tackled by a feasibility problem in terms of linear matrix inequalities. A simulati…

Adiabatic invariant change due to separatrix crossing at sweeping through a Feshbach resonance in a nonlinear two-mode system.

2007

Extreme nuclear magnetic resonance: Zero field, single spins, dark matter….

2019

An unusual regime for liquid-state nuclear magnetic resonance (NMR) where the magnetic field strength is so low that the $J$-coupling (intramolecular spin-spin) interactions dominate the spin Hamiltonian opens a new paradigm with applications in spectroscopy, quantum control, and in fundamental-physics experiments, including searches for well-motivated dark-matter candidates. An interesting possibility is to bring this kind of "extreme NMR" together with another one---single nuclear spin detected with a single-spin quantum sensor. This would enable single-molecule $J$-spectroscopy.

Quantum algorithms for search with wildcards and combinatorial group testing

2012

We consider two combinatorial problems. The first we call "search with wildcards": given an unknown n-bit string x, and the ability to check whether any subset of the bits of x is equal to a provided query string, the goal is to output x. We give a nearly optimal O(sqrt(n) log n) quantum query algorithm for search with wildcards, beating the classical lower bound of Omega(n) queries. Rather than using amplitude amplification or a quantum walk, our algorithm is ultimately based on the solution to a state discrimination problem. The second problem we consider is combinatorial group testing, which is the task of identifying a subset of at most k special items out of a set of n items, given the…

High homogeneity permanent magnet for diamond magnetometry

2020

Abstract Halbach magnets are a source of homogeneous magnetic field in an enclosed volume while keeping stray fields at a minimum. Here, we present the design, construction, and characterization for a stack of two Halbach rings with 10 cm inner diameter providing a homogeneous ( 100 ppm over 1.0 × 1.0 × 0.5 cm 3 ) magnetic field of around 105 mT, which will be used for a diamond based microwave-free widefield imaging setup. The final characterization is performed with a novel fiberized diamond-based sensor on a 3D translation stage documenting the high homogeneity of the constructed Halbach array and its suitability for the proposed use.

Novel mechanism for primordial perturbations in minimal extensions of the Standard Model

2020

Abstract We demonstrate that light spectator fields in their equilibrium can source sizeable CMB anisotropies through modulated reheating even in the absence of direct couplings to the inflaton. The effect arises when the phase space of the inflaton decay is modulated by the spectator which generates masses for the decay products. We call the mechanism indirect modulation and using the stochastic eigenvalue expansion show that it can source perturbations even four orders of magnitude larger than the observed amplitude. Importantly, the indirect mechanism is present in the Standard Model extended with right- handed neutrinos. For a minimally coupled Higgs boson this leads to a novel lower bo…

Detecting the long-distance structure of the X(3872)

2014

We study the X(3872)-->D^0 \bar D^0 \pi^0 decay within a D \bar D^* molecular picture for the X(3872) state. This decay mode is more sensitive to the long-distance structure of the X(3872) resonance than its J/\psi\pi\pi and J/\psi3\pi decays, which are mainly controlled by the details of the X(3872) wave function at short distances. We show that the D^0 \bar D^0 final state interaction can be important, and that a precise measurement of this partial decay width can provide valuable information on the interaction strength between the D^{(*)} \bar D^{(*)} charm mesons.

Light sterile neutrino sensitivity at the nuSTORM facility

2014

A facility that can deliver beams of electron and muon neutrinos from the decay of a stored muon beam has the potential to unambiguously resolve the issue of the evidence for light sterile neutrinos that arises in short-baseline neutrino oscillation experiments and from estimates of the effective number of neutrino flavors from fits to cosmological data. In this paper, we show that the nuSTORM facility, with stored muons of 3.8 GeV/c $\pm$ 10%, will be able to carry out a conclusive muon neutrino appearance search for sterile neutrinos and test the LSND and MiniBooNE experimental signals with 10$\sigma$ sensitivity, even assuming conservative estimates for the systematic uncertainties. This…

Search for short baseline nu(e) disappearance with the T2K near detector

2015

8 pages.- 6 figures

Radiogenic backgrounds in the NEXT double beta decay experiment

2019

[EN] Natural radioactivity represents one of the main backgrounds in the search for neutrinoless double beta decay. Within the NEXT physics program, the radioactivity- induced backgrounds are measured with the NEXT-White detector. Data from 37.9 days of low-background operations at the Laboratorio Subterraneo de Canfranc with xenon depleted in Xe-136 are analyzed to derive a total background rate of (0.84 +/- 0.02) mHz above 1000 keV. The comparison of data samples with and without the use of the radon abatement system demonstrates that the contribution of airborne-Rn is negligible. A radiogenic background model is built upon the extensive radiopurity screening campaign conducted by the NEX…