共查询到7条相似文献,搜索用时 0 毫秒
1.
M D Srinivas 《Pramana》1981,17(3):203-216
A complete solution is given to the problem of calculating the dead time corrections to the counting statistics of an arbitrary
doubly stochastic Poisson process with a non-negative random intensity function. It is shown that for the particular case
of an optical field with constant intensity, the general dead time modified counting formula leads to a corrected version
of results earlier derived by Bedard. 相似文献
2.
M D Srinivas 《Pramana》1996,47(1):1-23
We present an overview of the quantum theory of continuous measurements and discuss some of its important applications in
quantum optics. Quantum theory of continuous measurements is the appropriate generalization of the conventional formulation
of quantum theory, which is adequate to deal with counting experiments where a detector monitors a system continuously over
an interval of time and records the times of occurrence of a given type of event, such as the emission or arrival of a particle.
We first discuss the classical theory of counting processes and indicate how one arrives at the celebrated photon counting
formula of Mandel for classical optical fields. We then discuss the inadequacies of the so called quantum Mandel formula.
We explain how the unphysical results that arise from the quantum Mandel formula are due to the fact that the formula is obtained
on the basis of an erroneous identification of the coincidence probability densities associated with a continuous measurement
situation. We then summarize the basic framework of the quantum theory of continuous measurements as developed by Davies.
We explain how a complete characterization of the counting process can be achieved by specifying merely the measurement transformation
associated with the change in the state of the system when a single event is observed in an infinitesimal interval of time.
In order to illustrate the applications of the quantum theory of continuoius measurements in quantum optics, we first derive
the photon counting probabilities of a single-mode free field and also of a single-mode field in interaction with an external
source. We then discuss the general quantum counting formula of Chmara for a multi-mode electromagnetic field coupled to an
external source. We explain how the Chmara counting formula is indeed the appropriate quantum generalization of the classical
Mandel formula. To illustrate the fact that the quantum theory of continuous measurements has other diverse applications in
quantum optics, besides the theory of photodetection, we summarize the theory of ‘quantum jumps’ developed by Zoller, Marte
and Walls and Barchielli, where the continuous measurements framework is employed to evaluate the statistics of photon emission
events in the resonance fluorescence of an atomic system. 相似文献
3.
A gauge-invariant Green’s function approach to the quantum transport of spatially confined electrons in strong electromagnetic fields is presented. The theory includes mean field and exchange effects, as well as collisions and initial correlations. It allows for a self-consistent treatment of spectral properties and collective effects (plasmons), on one hand, and nonlinear field phenomena, such as harmonic generation and multiphoton absorption, on the other. It is equally applicable to electrons in quantum dots, ultracold ions in traps and valence electrons of metal clusters. 相似文献
4.
T. Golubeva Yu. Golubev C. Fabre N. Treps 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):179-193
In this paper, we investigate several properties of the
full signal-idler-pump mode quantum state generated by a triply
resonant non-degenerate Optical Parametric Oscillator operating
above threshold, with an injected wave on the signal and idler
modes in order to lock the phase diffusion process. We determine
and discuss the spectral purity of this state, which turns out not
to be always equal to 1 even though the three interacting modes
have been taken into account at the quantum level. We have seen
that the purity is essentially dependent on the weak
intensity of the injected light and on an asymmetry of the
synchronization. We then derive the expression of its total
three-mode Glauber P-function, and calculate the joint
signal-idler photon number probability distribution and
investigate their dependence on the injection. 相似文献
5.
S. De Nicola R. Fedele M. A. Man'ko V. I. Man'ko 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(2):191-198
Using the tomographic probability distribution (symplectic tomogram)
describing the quantum state (instead of the wave function or
density matrix) and properties of recently introduced tomographic
entropy associated with the probability distribution, the new
uncertainty relation for the tomographic entropy is obtained.
Examples of the entropic uncertainty relation for squeezed states
and solitons of the Bose-Einstein condensate are considered. 相似文献
6.
A. Luis L.L. Sánchez-Soto 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(2):195-200
We reconsider the problem of the sum and difference of two angle variables in quantum mechanics. The spectra of the sum and
difference operators have widths of , but angles differing by are indistinguishable. This means that the angle sum and difference probability distributions must be cast into a range. We obtain probability distributions for the angle sum and difference and relate this problem to the representation
of nonbijective canonical transformations.
Received: 6 December 1997 / Revised: 15 April 1998 / Accepted: 7 May
1998 相似文献
7.
给出运动空间区域中充满介质的情况下,以及运动空间区域中包含有介质和真空的情况下,矢量场的散度在运动空间区域中的体积分随时间变化率的两种计算方法.阐明了若以一种特别的方法来看待空间积分区域的变动,那么两种情况就可以用统一的方式来计算.指出在运动空间区域中包含有介质和真空的情况下,如果保留速度v在积分区域V的边界面S上的值和实际情况一样,而赋予区域V以一个其空间变化率连续或者分块连续的新的速度场v(r,t),那么锁定体元的计算方法仍然适用. 相似文献