Quantum Dynamical Echoes in the Spin 'Diffusion' in Mesoscopic Systems

TL;DR

This paper predicts quantum dynamical echoes in spin diffusion within mesoscopic systems, analyzing how interference phenomena affect local spin polarization evolution and proposing NMR sequences to observe these effects.

Contribution

It introduces conditions for observing quantum dynamical echoes in mesoscopic spin systems using NMR techniques and analyzes the impact of probe non-ideality on experimental features.

Findings

Quantum dynamical echoes can be observed in mesoscopic spin systems.

NMR sequences can be used to detect interference phenomena in spin diffusion.

Probe non-ideality explains certain experimental features.

Abstract

The evolution of local spin polarization in finite systems involves interference phenomena that give rise to {\bf quantum dynamical echoes }and non-ergodic behavior. We predict the conditions to observe these echoes by exploiting the NMR sequences devised by Zhang et al. [Phys. Rev. Lett. {\bf % 69}, 2149 (1992)], which uses a rare $^{13}$C as {\bf local probe }for a dipolar coupled $^1$H spin system. The non-ideality of this probe when testing mesoscopic systems is carefully analyzed revealing the origin of various striking experimental features.