Storage of classical information in quantum spins

TL;DR

This paper investigates how classical information can be stored and read in quantum spins, highlighting fundamental differences between integer and semi-integer spins, and discussing limits to magnetic bit miniaturization.

Contribution

It reveals fundamental distinctions between integer and semi-integer spins for information storage and readout, impacting the development of magnetic data storage at atomic scales.

Findings

Differences between integer and semi-integer spins affect information read/write processes.

Quantum spin tunneling imposes limits on magnetic bit stability.

Back-action of readout influences the fidelity of classical information storage.

Abstract

Digital magnetic recording is based on the storage of a bit of information in the orientation of a magnetic system with two stable ground states. Here we address two fundamental problems that arise when this is done on a quantized spin: quantum spin tunneling and back-action of the readout process. We show that fundamental differences exist between integer and semi-integer spins when it comes to both, read and record classical information in a quantized spin. Our findings imply fundamental limits to the miniaturization of magnetic bits and are relevant to recent experiments where spin polarized scanning tunneling microscope reads and records a classical bit in the spin orientation of a single magnetic atom.