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

Journal Article · Mon Nov 15 00:00:00 EST 2021 · Annals of Physics

DOI:https://doi.org/10.1016/J.AOP.2021.168655· OSTI ID:23183189

Segnorile, H.H., E-mail: [e-mail]; González, C.E., E-mail: [e-mail]; Zamar, R.C., E-mail: [e-mail] ^[1]

---

1. Facultad de Matemática, Astronomía, Física y Computación (FAMAF), Universidad Nacional de Córdoba, M. Allende y H. de la Torre - Ciudad Universitaria, Córdoba, X5016LAE (Argentina)

Highlights: • System–environment quantum correlation: a main solid state NMR decoherence channel. • Non-separable system–environment model yields realistic spin decoherence rates. • New open quantum system approach explains irreversible decay of refocused NMR echoes. • Adiabatic quantum decoherence is inherently irreversible and eigen-selective. This work addresses adiabatic quantum decoherence of many-body spin systems coupled with a boson field in the framework of open quantum systems theory. We generalize the traditional spin-boson model by considering a system–environment interaction Hamiltonian that represents a partition of non-interacting subsystems and highlights the collective correlation that appears exclusively due to the coupling with a common environment. Remarkably, this simple, exactly solvable model encompasses relevant aspects of a many-body open quantum system and features the subtle quantum effects that arise when the size scales up to a macroscopic level. We derive an analytical expression for the time dependence of the density matrix elements (in the preferred basis) without assuming coarse-graining. The resulting decoherence function is eigen-selective and is a complex exponential whose exponent has a real part that introduces a decay similar to that in the spin-boson model. On the contrary, the imaginary part depends on the quantum numbers and geometry of the whole partition and does not reflect the system temperature. Motivated by decoherence in solid-state NMR, and in search of realistic numerical estimations, we apply the theoretical results to a partition of dipole-coupled spin pairs in contact with a common phonon bath, using typical parameters of hydrated salts. The proposal allows estimating the decoherence time scale in terms of the system physical constants: sound velocity and eigenvalue distribution width. As a significant novelty, the decoherence function phase depends on the eigenvalue distribution throughout the sample. It plays the leading role, overshadowing the mechanism associated with the bath thermal state. Finally, we apply the formalism to describe decoherence in the “magic echo” NMR reversal experiment. We find that the system–environment correlation explains the origin of irreversibility, and both the decoherence rate value and its dependence on the dipolar frequency, are remarkably similar to the experiment.

• OSTI ID: 23183189
• Journal Information: Annals of Physics, Vol. 434; Other Information: Copyright (c) 2021 Elsevier Inc. All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-4916
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BOSONS
DECAY
DENSITY MATRIX
EIGENVALUES
EXACT SOLUTIONS
GEOMETRY
HAMILTONIANS
MANY-BODY PROBLEM
MATRIX ELEMENTS
NUCLEAR MAGNETIC RESONANCE
PHONONS
QUANTUM DECOHERENCE
QUANTUM NUMBERS
QUANTUM SYSTEMS
SOUND WAVES
SPIN
TIME DEPENDENCE