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T Gorin

Publications and source records attributed to T Gorin.

7 recordsLinked to original sources
PubMed2006

Anomalous slow fidelity decay for symmetry-breaking perturbations.

Symmetries as well as other special conditions can cause anomalous slowing down of fidelity decay. These situations will be characterized, and a family of random matrix models to emulate them generically presented. An analytic solution based on exponentiated linear response will be given. For one representative case the exact solution is obtained from a supersymmetric calculation. The results agree well with dynamical calculations for a kicked top.

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PubMed2006

Scattering fidelity in elastodynamics.

The recent introduction of the concept of scattering fidelity causes us to revisit the experiment by Lobkis and Weaver [Phys. Rev. Lett. 90, 254302 (2003)]. There, the "distortion" of the coda of an acoustic signal is measured under temperature changes. This quantity is, in fact, the negative logarithm of scattering fidelity. We reanalyze their experimental data for two samples, and we find good agreement with random matrix predictions for the standard fidelity. Usually, one may expect such an agreement for chaotic systems, only. While the first sample may indeed be assumed chaotic, for the second sample, a perfect cuboid, such an agreement is surprising. For the first sample, the random matrix analysis yields perturbation strengths compatible with semiclassical predictions. For the cuboid, the measured perturbation strengths are by a common factor of 5/3 too large. Apart from that, the experimental curves for the distortion are well reproduced.

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PubMed2005

Experimental verification of fidelity decay: from perturbative to fermi golden rule regime.

The scattering matrix was measured for a flat microwave cavity with classically chaotic dynamics. The system can be perturbed by small changes of the geometry. We define the "scattering fidelity" in terms of parametric correlation functions of scattering matrix elements. In chaotic systems and for weak coupling, the scattering fidelity approaches the fidelity of the closed system. Without free parameters, the experimental results agree with random matrix theory in a wide range of perturbation strengths, reaching from the perturbative to the Fermi golden rule regime.

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PubMed2002

Signatures of the correlation hole in total and partial cross sections.

In a complex scattering system with few open channels, say a quantum dot with leads, the correlation properties of the poles of the scattering matrix are most directly related to the internal dynamics of the system. We may ask how to extract these properties from an analysis of cross sections. In general this is very difficult, if we leave the domain of isolated resonances. We propose to consider the cross correlation function of two different elastic or total cross sections. For these we can show numerically and to some extent also analytically a significant dependence on the correlations between the scattering poles. The difference between uncorrelated and strongly correlated poles is clearly visible, even for strongly overlapping resonances.

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PubMed2001

Comment on "Models of intermediate spectral statistics".

In this Comment we point out that the semi-Poisson is well suited only as a reference point for the so-called "intermediate statistics," which cannot be interpreted as a universal ensemble, like the Gaussian orthogonal ensemble or the Poissonian statistics. In Ref. 2 it was proposed that the nearest-neighbor distribution P(s) of the spectrum of a Poissonian distributed matrix perturbed by a rank one matrix is similar to the semi-Poisson distribution. We show, however, that the P(s) of this model differs considerably in many aspects from the semi-Poisson. In addition, we give an asymptotic formula for P(s) as s-->0, which gives P'(0)=pisqrt[3]/2 for the slope at s=0. This is different not only from the GOE case, but also from the semi-Poisson prediction.

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