Magnetic adatoms as memory bits: A quantum master equation analysis

Abstract

Due to underlying symmetries the ground states of magnetic adatoms may be highly stable, which opens perspectives for application as single-atom memory. A specific example is a single holmium atom (with $J=8$) on a platinum (111) surface for which exceptionally long lifetimes were observed in recent scanning tunneling microscopy studies. For control and read-out the atom must be coupled to electronic contacts. Hence the spin dynamics of the system is governed by a quantum master equation. Our analysis shows that in general it cannot be reduced to a classical master equation in the basis of the unperturbed crystal-field Hamiltonian. Rather, depending on parameters and control fields, "environment induced superselection" principles choose the appropriate set of basis states, which in turn determines the specific relaxation channels and lifetimes. Our simulations suggest that in ideal situations the lifetimes should be even longer than observed in the experiment. We, therefore, investigate the influence of various perturbations. We also study the initialization process of the state of the Ho atom by applied voltage pulses and conclude that fast, high fidelity preparation, on a $100\text{ns}$ timescale, should be possible.

14 pages, 11 figures

References in corpus (11)

• Decoherence, einselection, and the quantum origins of the classical
• Magnetic Anisotropy and Magnetization Dynamics of Individual Atoms and Clusters of Fe and Co on Pt(111)
• Spin-transfer torque on a single magnetic adatom
• Spin Inelastic Electron Tunneling Spectroscopy on Local Spin Adsorbed on Surface
• Quantum Darwinism, Classical Reality, and the Randomness of Quantum Jumps
• Symmetry effects on spin switching of adatoms
• Storage of classical information in quantum spins
• Time local master equation connecting the Born and Markov approximations
• Electroluminescence and multi-photon effects in a resonator driven by a tunnel junction
• Influence of two-level fluctuators on adiabatic passage techniques
• Spectroscopy of the transition-rate matrix for molecular junctions: dynamics in the Franck-Condon regime

Cited by in corpus (6)

• Spin decoherence of magnetic atoms on surfaces
• Spin-1 two-impurity Kondo problem on a lattice
• Electron-assisted magnetization tunneling in single spin systems
• Manipulation and readout of spin states of a single-molecule magnet by a spin-polarized current
• The geometric phase of Z${}_n$- and T-symmetric nanomagnets as a classification toolkit
• Inelastic electron tunneling through adatoms and molecular nanomagnets