منابع مشابه
Decoherence of spin echoes
We define a quantity, the so-called purity fidelity, which measures the rate of dynamical irreversibility due to decoherence, observed e.g in echo experiments, in the presence of an arbitrary small perturbation of the total (system + environment) Hamiltonian. We derive a linear response formula for the purity fidelity in terms of integrated time correlation functions of the perturbation. Our re...
متن کاملSpin Echoes
Intense radiofrequency power in the form of pulses is applied to an ensemble of spins in a liquid placed in a large static magnetic Geld H&. The frequency of the pulsed r-f power satisGes the condition for nuclear magnetic resonance, and the pulses last for times which are short compared with the time in which the nutating macroscopic magnetic moment of the entire spin ensemble can decay. After...
متن کاملDecoherence and Loschmidt echoes: Quantum against Classical
Studies of stability of quantum time evolution with respect to small variation in the Hamiltonian have attracted considerable interest in recent years [1–5]. Quite remarkable is the fact that the problem has been practically intact until 2001, with exception of experimental studies of the group of Pastawski [6] in the mid 1990’s. However, one has to mention the pioneering paper of Peres in 1984...
متن کاملPulsed NMR Spin Echoes
Pulsed nuclear magnetic resonance techniques with transverse radiofrequency pulses are used to determine the spin-lattice and spin-spin relaxation times of glycerol and Fe solutions of varying concentrations. The nuclear magnetic moments of flourine and hydrogen are found to be μH+ = (1.408± .008)× 10−26 J/T and μF− = (1.324± .007)× 10−26 J/T, respectively. A negative linear relation in log-log...
متن کاملFundamental Properties of Spin Echoes
Spin echoes have been known since 1950. Although their formal description by use of the Bloch equations is straightforward, it does not lead to an intuitive understanding of their behavior except for the special cases of 180" or 90" pulses, especially when many pulses are applied before the magnetization has returned into thermal equilibrium. The extended-phasegraph algorithm, which takes into ...
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ژورنال
عنوان ژورنال: Journal of Physics A: Mathematical and General
سال: 2002
ISSN: 0305-4470
DOI: 10.1088/0305-4470/35/22/304