Effective one-body dynamics in multiple-quantum NMR experiments

TL;DR

This paper demonstrates that in certain NMR experiments, complex many-body spin dynamics can be effectively reduced to one-body dynamics, especially in quasi-1D systems like hydroxyapatite, with quantum Zeno effect and decoherence analysis supporting this simplification.

Contribution

It introduces a method to observe effective one-body dynamics in multi-spin NMR systems and shows how quasi-1D structures and quantum Zeno effect facilitate this reduction.

Findings

Effective one-dimensional behavior observed in hydroxyapatite

Quantum Zeno effect enhances quasi-1D dynamics

Decoherence in HAp follows a smooth exponential decay

Abstract

A suitable NMR experiment in a one-dimensional dipolar coupled spin system allows one to reduce the natural many-body dynamics into effective one-body dynamics. We verify this in a polycrystalline sample of hydroxyapatite (HAp) by monitoring the excitation of NMR many-body superposition states: the multiple-quantum coherences. The observed effective one-dimensionality of HAp relies on the quasi 1d structure of the dipolar coupled network that, as we show here, is dynamically enhanced by the quantum Zeno effect. Decoherence is also probed through a Loschmidt echo experiment, where the time reversal is implemented on the double-quantum Hamiltonian, I_{i,+}I_{j,+} + I_{i,-}I_{j,-}. We contrast the decoherence of adamantane, a standard 3d system, with that of HAp. While the first shows an abrupt Fermi-type decay, HAp presents a smooth exponential law.