Quantum revivals and magnetization tunneling in effective spin systems

Abstract

Quantum mechanical objects or nano-objects have been proposed as bits for information storage. While time-averaged properties of magnetic, quantum-mechanical particles have been extensively studied experimentally and theoretically, experimental investigations of the real time evolution of magnetization in the quantum regime were not possible until recent developments in pump-probe techniques. Here we investigate the quantum dynamics of effective spin systems by means of analytical and numerical treatments. Particular attention is paid to the quantum revival time and its relation to the magnetization tunneling. The quantum revival time has been initially defined as the recurrence time of a total wave-function. Here we show that the quantum revivals of wave-functions and expectation values in spin systems may be quite different which gives rise to a more sophisticated definition of the quantum revival within the realm of experimental research. Particularly, the revival times for integer spins coincide which is not the case for half-integer spins. Furthermore, the quantum revival is found to be shortest for integer ratios between the on-site anisotropy and an external magnetic field paving the way to novel methods of anisotropy measurements. We show that the quantum tunneling of magnetization at avoided level crossing is coherent to the quantum revival time of expectation values, leading to a connection between these two fundamental properties of quantum mechanical spins.

Effects of Impurities and Deformations on Electronic Effective Mass in Quantum Revival Time within the Infinite Square Well

“…For positive energies E = h2 k 2 2m > 0, the solution of the Schrödinger equation, satisfying the boundary conditions in Eqs. (2,4), is expressed as:…”

Effects of Impurities and Deformations on Electronic Effective Mass in Quantum Revival Time within the Infinite Square Well

“…It is characterized by the recurrence of interference patterns in the probability density of finding the system in different states. Quantum revival is a fundamental aspect of quantum mechanics with applications in various fields, including quantum information processing [4,5] and condensed matter physics [6]. As is well known, it has counterparts in other branches of physics.…”

Ordered space-time structures: Quantum carpets from Gaussian sum theory

“…Quantum carpets depict the behavior of the wave function evolution in the space-time, exhibiting a key feature showing the emergence of the initial wave function after the"revival time" [20]. Essentially, the occurrence of the revival patterns in quantum carpets are due to the phase alignment of the neighboring eigenstates during the evolution [21][22][23][24][25][26][27][28][29][30]. Experimentally, the properties of quantum carpets have been illustrated in a wide class of systems, for example, Rydberg atom [31], optical lat-tice [32], cavity quantum electrodynamic systems [33], optical waveguide [34], and so on.…”