Echoes and revival echoes in systems of anharmonically confined atoms

Abstract

We study echoes and what we call 'revival echoes' for a collection of atoms that are described by a single quantum wavefunction and are confined in a weakly anharmonic trap. The echoes and revival echoes are induced by applying two, successive temporally localized potential perturbations to the confining potential, one at time $t=0$, and a smaller one at time $t=\tau$. Pulse-like responses in the expectation value of position $<x(t)>$ are predicted at $t \approx n\tau$ ($n=2,3,...$) and are particularly evident at $t \approx 2\tau$. A novel result of our study is the finding of 'revival echoes'. Revivals (but not echoes) occur even if the second perturbation is absent. In particular, in the absence of the second perturbation, the response to the first perturbation dies away, but then reassembles, producing a response at revival times $mT_x$ ($m=1,2,...$). Including the second perturbation at $t=\tau$, we find temporally localized responses, revival echoes, both before and after $t\approx mT_x$, e.g., at $t\approx m T_x-n \tau$ (pre-revival echoes) and at $t\approx mT_x+n\tau$, (post-revival echoes), where $m$ and $n$ are $1,2,...$ . Depending on the form of the perturbations, the 'principal' revival echoes at $t \approx T_x \pm \tau$ can be much larger than the echo at $t \approx 2\tau$. We develop a perturbative model for these phenomena, and compare its predictions to the numerical solutions of the time-dependent Schr\"odinger Equation. The scaling of the size of the various echoes and revival echoes as a function of the symmetry and size of the perturbations applied at $t=0$ and $t=\tau$ is investigated. We also study the presence of revivals and revival echoes in higher moments of position, $<x^p (t)>$, $p>1$, and the effect of atom-atom interactions on these phenomena.Comment: 33 pages, 13 figures, corrected typos and added reference

Orientation and Alignment Echoes

“…[14]). Echoes are being also discussed in the context o f cavity quantum electrodynam ics [15,16] and cold atom systems [17][18][19][20].…”

Echoes in a Single Quantum Kerr-nonlinear Oscillator

“…Over the years, echoes have been discovered in various physical systems, such as systems consisting of many interacting/non-interacting particles, or single quantum particles. Examples of echoes in many-particle systems include photon echoes [3,4], neutron spin echo [5], cyclotron echoes [6], plasma-wave echoes [7], cold atom echoes in optical traps [8][9][10], echoes in particle accelerators [11][12][13][14], echoes in free-electron lasers [15], and echoes in laser-kicked molecules [16][17][18]. In addition, echoes have been observed in single quantum systems, such as atoms interacting with a quantized mode of electromagnetic radiation [19,20], and in single vibrationally excited molecules [21].…”

Impulsively Excited Gravitational Quantum States: Echoes and Time-resolved Spectroscopy

“…A spectacular effect in the dynamics of kick-excited nonlinear systems is the echo phenomenon first discovered by E. Hahn in spin systems [38,39] (spin echo). Since then, various types of echoes have been observed, including photon echoes [40,41], cyclotron echoes [42], plasma-wave echoes [43], neutron spin echo [44], cold atom echoes in optical traps [45][46][47], echoes in particle accelerators [48][49][50][51][52], and more recently-alignment and orientation echoes in molecular gases [53][54][55][56][57][58][59][60][61]. In these examples, echo appears in inhomogeneous ensembles of many particles evolving at different frequencies.…”