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At least 631 records · Page 35Linked to original sources
PubMed2000

Rydberg electron interferometry

A recent quantum mechanical study [W. Isaacs and M. A. Morrison, Phys. Rev. A 57, R9 (1998)] discovered pronounced oscillations in cross sections for near-resonant energy transfer collisions of rare-gas atoms with initially aligned Rydberg atoms. We analyze such collisions for 17d(m)-->18p(m(')) transitions in the Ca-He system semiclassically and show that the oscillations arise from a phase interference process unique to Rydberg target states. In addition to explaining the origin of these structures, this analysis explains their disappearance when the relative Ca-He velocity goes to infinity and/or the energy defect vanishes and their dependence on the initial and final magnetic quantum numbers of the transition.

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PubMed2000

Large area light-pulse atom interferometry

We report the experimental demonstration of a large area atom interferometer based on extended sequences of light pulses. We characterize the interferometer through measurement of the acceleration due to gravity and demonstrate a threefold enhancement in intrinsic acceleration sensitivity. The technique is applicable to many atom interferometer configurations, including those used for measurement of rotations, gravity gradients, and Planck's over 2pi/m.

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PubMed2000

Optimal states and almost optimal adaptive measurements for quantum interferometry

We derive the optimal N-photon two-mode input state for obtaining an estimate straight phi of the phase difference between two arms of an interferometer. For an optimal measurement [B. C. Sanders and G. J. Milburn, Phys. Rev. Lett. 75, 2944 (1995)], it yields a variance (Deltastraight phi)(2) approximately pi(2)/N2, compared to O(N-1) or O(N-1/2) for states considered by previous authors. Such a measurement cannot be realized by counting photons in the interferometer outputs. However, we introduce an adaptive measurement scheme that can be thus realized, and show that it yields a variance in straight phi very close to that from an optimal measurement.

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PubMed2000

Picometer accuracy in measuring lattice displacements across planar faults by interferometry in coherent electron diffraction

We calculate the shadow image in far field below a thin crystal when a coherent electron source is placed at micrometer distances above the specimen, and note that the presence of a planar fault results in very strong oscillatory contrast. We realize these predictions experimentally using a field-emission electron source in a microscope. With this technique, we determine displacement vectors at planar faults with an accuracy down to 1 pm in studies of the Bi2Sr2CaCu2O8 superconductor containing thin intercalated layers.

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PubMed2001

Geometric phase of three-level systems in interferometry.

We present the first scheme for producing and measuring an Abelian geometric phase shift in a three-level system where states are invariant under a non-Abelian group. In contrast to existing experiments and proposals for experiments, based on U(1)-invariant states, our scheme geodesically evolves U(2)-invariant states in a four-dimensional SU(3)/U(2) space and is physically realized via a three-channel optical interferometer.

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PubMed2001

Pion interferometry at RHIC: porobing a thermalized quark-gluon plasma?

We calculate the Gaussian radius parameters of the pion-emitting source in high-energy heavy-ion collisions, assuming a first-order phase transition from a thermalized quark-gluon plasma (QGP) to a gas of hadrons. Such a model leads to a very long-lived dissipative hadronic rescattering phase which dominates the properties of the two-pion correlation functions. The radii are found to depend only weakly on the thermalization time tau(i), the critical temperature Tc (and thus the latent heat), and the specific entropy of the QGP. The model calculations suggest a rapid increase of R(out)/R(side) as a function of KT if a thermalized QGP were formed.

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PubMed2001

Reaction imaging with interferometry.

We analyze scattering into a double-slit interferometer with target-fragment recoil detection as a monitor of quantum correlation and entanglement in few-body reaction amplitudes. We thus investigate two-slit interference with which-way information as an enhancement to modern reaction-fragment detection. We briefly consider charged-particle scattering with recoil-ion detection from the point of view of quantum information.

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PubMed2001

Pion Interferometry of square root of (s(NN)) =130 GeV Au + Au collisions at RHIC.

Two-pion correlation functions in Au+Au collisions at square root of [s(NN)] = 130 GeV have been measured by the STAR (solenoidal tracker at RHIC) detector. The source size extracted by fitting the correlations grows with event multiplicity and decreases with transverse momentum. Anomalously large sizes or emission durations, which have been suggested as signals of quark-gluon plasma formation and rehadronization, are not observed. The Hanbury Brown-Twiss parameters display a weak energy dependence over a broad range in square root of [s(NN)].

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PubMed2002

X-ray interferometry with multicrystal components using intensity correlation.

A theoretical relation between intensity correlation and interference was experimentally verified for the case of a large-separation skew-symmetric bicrystal interferometer. The intensity correlation was enhanced in the angular range where the interference fringes were clearly observed. An application investigating the interference condition of the interferometer is presented using the intensity-correlation technique.

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