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Nicholas J. Curro Charles P. Slichter 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,130(2):186-194
Measurement ofT2G, the Gaussian component of the spin-echo envelope of planar Cu nuclei in high-temperature superconductors, gives important information about the real part of the Cu electron spin susceptibility. In the traditional picture of the planar Cu echo decay, the internuclear coupling is assumed to remain static with respect to spin–lattice relaxation and mutual exchange fluctuations. In some circumstances, however, this assumption breaks down. We calculate the internuclear corrections arising from spin–lattice relaxation to the conventional theory ofT2Gand show thatT2Gcan be easily corrected for these effects. We argue that mutual exchanges due to the perpendicular indirect couplings are suppressed in these materials. For YBa2Cu4O8, we find a correction on the order of 10% inT2Gand using the corrected values we find that the isotope ratio63T2G/65T2Gagrees with theory. 相似文献
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We continuously measure the state of a superconducting quantum bit coupled to a microwave readout cavity by using a fast, ultralow-noise parametric amplifier. This arrangement allows us to observe quantum jumps between the qubit states in real time, and should enable quantum error correction and feedback--essential components of quantum information processing. 相似文献
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C. P. Slichter S. E. Barrett J. A. Martindale D. J. Durand C. H. Pennington C. A. Klug K. E. O’Hara S. M. DeSoto T. Imai J. P. Rice T. A. Friedmann D. M. Ginsberg 《Applied magnetic resonance》1992,3(3-4):423-448
The authors review and up-date their work on Knight shifts, spin-lattice relaxation, and indirect nuclear spin-spin coupling for YBa2Cu3O7 in the superconducting state. The data are analyzed in particular to show what it may indicate about the orbital and spin pairing of the superconducting state. 相似文献
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The authors carried out a low field (6.3 kOe) NMR measurement of the Gaussian component of63Cu nuclear spin-spin relaxation rate 1/T 2G at the planar Cu site in a high-T c superconductor YBa2Cu3O6.9 (T c=92 K). They demonstrate that the results provide quantitative information concerning the static spin susceptibility χ′(q) at non-zero wave vector q. The detailed analysis of the data assuming a model susceptibility peaked at the corner of first Brillouin zone q=Q (Q=(π/a, θ/a),a: lattice constant) shows that χ′(q) satisfies a Curie-Weiss law around q=Q. Stoner enhancement over the calculated Lindhard function at q=Q is estimated to be of the order of ~10–20. They also demonstrate that combined analysis of 1/T 1 and 1/T 2G allows one to judge whether anomalous shift of the low frequency spectral weight of χ″(Q,ω) to higher frequencies (i.e.pseudo gap) exists or not. Application of the method to YBa2Cu3O6.9 revealed no appreciable pseudo gap in the material. 相似文献
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ter Steege DH Smits M de Lange CA Westwood NP Peel JB Visscher L 《Faraday discussions》2000,(115):259-69; discussion 303-30
A (2 + 1) one-colour resonance-enhanced multiphoton ionisation study is carried out on the C 2 sigma- state of the ClO radical in the one-photon energy range 29,500-31,250 cm-1. The ClO radical is produced by one-photon photolysis of ClO2 employing 359.2 nm photons derived from a separate laser. In this way a significant concentration of vibrationally excited ClO in its spin-orbit split X 2 pi omega (omega = 3/2 or 1/2) electronic ground state is produced. In addition to mass-resolved excitation spectra, kinetic-energy resolved photoelectron spectra for the X 3 sigma-(v+)<--C 2 sigma-(v' = 3-5) transitions are measured. These transitions are not completely Frank-Condon diagonal, and indicate a decrease in bond length on removal of the Rydberg electron from the C 2 sigma- state. In addition to an unambiguous assignment of the C 2 sigma- state, valuable information is obtained on the degree of vibrational excitation with which the nascent ClO radical is formed in the photolysis of ClO2. Analysis of the photoelectron spectra is supported by Franck-Condon calculations based on potential energy curves either from experimental spectroscopic parameters, or obtained by theoretical ab initio methods. 相似文献