5,223 research outputs found
Transport and magnetic behavior under pressure and high-resolution photoemission studies of Ce2Rh(o.7)Co(0.3)Si3, an alloy on the verge of quantum critical point
We report the influence of external pressure on the temperature dependence of
magnetization and electrical resistivity as well as high-resolution
photoemission studies for an alloy, Ce2Rh(0.7)Co(0.3)Si3, ordering magnetically
below 3 K. It is found that the external pressure has the same effect as that
induced by (further) Co substitution for Rh in the series, Ce2Rh(1-x)Co(x)Si3,
resulting in qualitative changes in the features in the magnetic and transport
data, with a suppression of magnetic ordering followed by quantum critical
point effect. The high-resolution spectra reveal signature of Kondo feature at
ambient feature. These findings support the validity of spin-density-wave
picture in this series.Comment: SCES2010 conferenc
Evolution of the Kondo resonance feature and its relationship to spin-orbit coupling across the quantum critical point in Ce2Rh{1-x}CoxSi3
We investigate the evolution of the electronic structure of Ce2Rh{1-x}CoxSi3
as a function of x employing high resolution photoemission spectroscopy. Co
substitution at the Rh sites in antiferromagnetic Ce2RhSi3 leads to a
transition from an antiferromagnetic system to a Kondo system, Ce2CoSi3 via the
Quantum Critical Point (QCP). High resolution photoemission spectra reveal
distinct signature of the Kondo resonance feature (KRF) and its spin orbit
split component (SOC) in the whole composition range indicating finite Kondo
temperature scale at the quantum critical point. We observe that the intensity
ratio of the Kondo resonance feature and its spin orbit split component,
KRF/SOC gradually increases with the decrease in temperature in the strong
hybridization limit. The scenario gets reversed if the Kondo temperature
becomes lower than the magnetic ordering temperature. While finite Kondo
temperature within the magnetically ordered phase indicates applicability of
the spin density wave picture at the approach to QCP, the dominant temperature
dependence of the spin-orbit coupled feature suggests importance of spin-orbit
interactions in this regime.Comment: 6 figure
Polarization in Poly (Vinyl Chloride) (PVC) and Poly (Methyl Methacrylate) (PMMA) Blends Films Investigated by Thermally Stimulated Depolarization Current Technique
Quickest Paths in Simulations of Pedestrians
This contribution proposes a method to make agents in a microscopic
simulation of pedestrian traffic walk approximately along a path of estimated
minimal remaining travel time to their destination. Usually models of
pedestrian dynamics are (implicitly) built on the assumption that pedestrians
walk along the shortest path. Model elements formulated to make pedestrians
locally avoid collisions and intrusion into personal space do not produce
motion on quickest paths. Therefore a special model element is needed, if one
wants to model and simulate pedestrians for whom travel time matters most (e.g.
travelers in a station hall who are late for a train). Here such a model
element is proposed, discussed and used within the Social Force Model.Comment: revised version submitte
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Towards quantum machine learning with tensor networks
Machine learning is a promising application of quantum computing, but challenges remain for implementation today because near-term devices have a limited number of physical qubits and high error rates. Motivated by the usefulness of tensor networks for machine learning in the classical context, we propose quantum computing approaches to both discriminative and generative learning, with circuits based on tree and matrix product state tensor networks, that could already have benefits with such near-term devices. The result is a unified framework in which classical and quantum computing can benefit from the same theoretical and algorithmic developments, and the same model can be trained classically then transferred to the quantum setting for additional optimization. Tensor network circuits can also provide qubit-efficient schemes in which, depending on the architecture, the number of physical qubits required scales only logarithmically with, or independently of the input or output data sizes. We demonstrate our proposals with numerical experiments, training a discriminative model to perform handwriting recognition using a hybrid quantum-classical optimization procedure that could be carried out on quantum hardware today, and testing the noise resilience of the trained model
Universal behavior of quantum Green's functions
We consider a general one-particle Hamiltonian H = - \Delta_r + u(r) defined
in a d-dimensional domain. The object of interest is the time-independent Green
function G_z(r,r') = . Recently, in one dimension (1D),
the Green's function problem was solved explicitly in inverse form, with
diagonal elements of Green's function as prescribed variables. The first aim of
this paper is to extract from the 1D inverse solution such information about
Green's function which cannot be deduced directly from its definition. Among
others, this information involves universal, i.e. u(r)-independent, behavior of
Green's function close to the domain boundary. The second aim is to extend the
inverse formalism to higher dimensions, especially to 3D, and to derive the
universal form of Green's function for various shapes of the confining domain
boundary.Comment: 46 pages, the shortened version submitted to J. Math. Phy
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