revival time
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2014 ◽  
Vol 89 (2) ◽  
pp. 157-166 ◽  
Author(s):  
P. Ghosh ◽  
S. Ghosh ◽  
N. Bera

2011 ◽  
Vol 09 (06) ◽  
pp. 1519-1531 ◽  
Author(s):  
SURANJANA GHOSH ◽  
IRENE MARZOLI

The time evolution of a particle, caught in an infinitely deep square well, displays unexpected features, when one includes tiny relativistic effects. Indeed, even the smallest corrections to the non-relativistic quadratic spectrum manifest themselves in a dramatic way. Our theoretical analysis brings to light a completely new time scale, at which the system exhibits surprisingly perfect revivals. This longer time scale rules the system dynamics and replaces the original revival time of the unperturbed system. The early manifestation of such phenomenon is captured by the sensitivity of sub-Planck structures for different values of the relativistic corrections.


2008 ◽  
Vol 22 (15) ◽  
pp. 2463-2471 ◽  
Author(s):  
RANJANA PRAKASH ◽  
PRAMILA SHUKLA

We report here results for collapses and revivals phenomenon for a collection of M two-level atoms contained in a volume having dimensions much smaller than the radiation wavelength and existing in the Dicke state |r,m〉. We use a perturbation approach and obtain in the lowest contributing order of perturbation second harmonic, besides the main Rabi frequency. The amplitude of the fundamental depends on m only, but the amplitude of the harmonic has dependence on r as well as m. If the atoms are in superradiant states, only the second harmonic is obtained. Revival time for the second harmonic is one half that for the fundamental. It is interesting to note that the number of atoms M does not matter in Rabi frequency, collapse times, revival times or in amplitudes, and only r and m matter. Values of r and m of atoms in a Dicke state can be determined, in principle, by observing Rabi oscillations and average atomic inversion.


2007 ◽  
Vol 21 (20) ◽  
pp. 3621-3642 ◽  
Author(s):  
HARI PRAKASH ◽  
RAKESH KUMAR

In the present paper, we consider the interaction of a single mode radiation initially in a coherent state with an assembly of two two-level atoms in some different states using the Hamiltonian, H = ω(a+a + Sz)+g(a S+ + a+ S-) in the natural units, where a+ and a are the creation and annihilation operators for radiation, Sz, S± are the collective Dicke operators, g is the coupling constant, ω is the energy of the photons and energy difference between the two atomic levels. We solve it exactly. We study ordinary squeezing and amplitude-squared squeezing of radiation for the general operators, [Formula: see text] and Yθ=1/2(a2e-iθ+a+2eiθ), when atoms are fully excited, super-radiant or in the ground state. We get a large ordinary squeezing (nearly 88% squeezing) for the super-radiant atomic state, at a time, which is 0.451 of the first revival time, and this should be easily observable. We also get a large amplitude-squared squeezing (nearly 20%) at the time, which is about 0.033 of the first revival time. Variation of variances near their minima with coupling time gt, square root of mean photon number |α| and phase are also discussed.


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