Displacement Echoes: Classical Decay and Quantum Freeze

Motivated by neutron scattering experiments, we investigate the decay of the fidelity with which a wave packet is reconstructed by a perfect time-reversal operation performed after a phase space displacement. In the semiclassical limit, we show that the decay rate is generically given by the Lyapunov exponent of the classical dynamics. For small displacements, we additionally show that, following a short-time Lyapunov decay, the decay freezes well above the ergodic value because of quantum effects. Our analytical results are corroborated by numerical simulations

World ocean annual mean absolute geostrophic velocity on marine geoid of EIGEN‐6C4 from WOA13

17 USC 105 interim-entered record; under review.The article of record as published may be found at http://dx.doi.org/10.1002/gdj3.124This data set was established from two open sources: (a) geoid undulation (N) from EIGEN-6C4, which is a static global combined gravity field model up to degree and order 2,190, and (b) ‘World ocean geostrophic velocity inverted from World Ocean Atlas 2013 with the P-vector method' (NCEI accession 0,121,576). With the given non-positive values of N in the oceans, absolute geostrophic currents (u, v) are easily obtained on N with 1°×1° resolution from the second data set except the equatorial zone (5oS – 5oN) due to the non-existence of the geostrophic balance. Altogether, the data set contains 15,868 (u, v) data pairs. The data set shows that the hypothetical situation that there would be no flow on the geoid does not exist.Research Office of the Naval Postgraduate SchoolIdentified in text as U.S. Government work