Irreversible adiabatic decoherence of dipole-interacting nuclear-spin pairs coupled with a phonon bath

Abstract

We report a first-principle theoretical study of the adiabatic decoherence undergone by a nuclear spin system in a solid, coupled to the phonon field through the dipolar interaction. The calculations are performed for a chain of weakly interacting 1/2-spin pairs, considered as an open quantum system in contact with a bosonic heat bath. By incorporating to the whole system Hamiltonian the fluctuations of the local dipolar energy produced by low frequency phonons, and assuming that this low energy fluctuations are adiabatic, we find that the spin dynamics can be described in closed form through a spin-boson model. The obtained results show that the coupling with the phonons destroy the spin coherence, and the efficiency of the process significantly depends on the complexity of the involved spin states. By using realistic values for the various parameters of the model, we conclude that this mechanism can be particularly efficient to degrade multi-spin coherences, when the number of 'active' spins involved in a given coherence is high. In this way, we show that the spin coherence in the adiabatic regime can be noticeably affected by this mechanism.

Adiabatic quantum decoherence in many non-interacting subsystems induced by the coupling with a common boson bath

“…( 23). This derivation generalizes the one presented in [17] to show explicitly both the real and imaginary parts of the decoherence function.…”

“…The work of ref. [17] presented a theoretical approach based on the spin-phonon model to describe the irreversible decoherence in a system of dipole interacting spin pairs, adiabatically coupled with a phonon bath. In that approach, the system-bath interaction is given by the variation of dipole intra-pair energy due to the coupling with a phonon environment, which in turn correlates different pairs through their collective dynamics.…”

“…The decoherent density matrix obtained in [17] was used to study the spin system purity, which can be conceived as an upper bound for the macroscopic observable magnetization (NMR signal amplitude) in a timereversal NMR experiment [12]. The purity decoherence rate yielded by this model has a clear dependence on the main dipolar coupling strength, while is practically independent of the sample temperature.…”

“…In this way we explore conditions that can be thought as an opposite limit of that analyzed in ref. [17], where decoherence efficiency is linked to the dynamics governed by the dipolar spin-flip terms, which enable the growth of multi-spin correlations. On the contrary, we now focus to models where such capability is inhibited by a clusterized distribution of the observed system [19,20].…”

Peculiarities of Rabi oscillations and free induction decay in two-component nuclear spin systems with Ising nuclei interactions

“…Special attention is paid there to the nuclear spin-spin interactions. This interest is due to the perspective of using such spin systems for quantum information processing and quantum simulation [7][8][9][10].…”