Unraveling spin entanglement using quantum gates with scanning tunneling microscopy-driven electron spin resonance

TL;DR

This paper demonstrates the deterministic creation of entangled spin states in a solid-state system using ESR-STM, showcasing its potential for atom-based quantum circuits and surface quantum state engineering.

Contribution

It introduces a method to generate and manipulate entangled spin states via quantum gates implemented with ESR-STM on a two-atom system.

Findings

Successfully generated Bell states with high fidelity

Demonstrated coherent control of two-qubit spin states

Validated the use of ESR-STM for entanglement creation

Abstract

Quantum entanglement is a fundamental resource for quantum information processing, and its controlled generation and detection remain key challenges in scalable quantum architectures. Here, we numerically demonstrate the deterministic generation of entangled spin states in a solid-state platform by implementing quantum gates via electron spin resonance combined with scanning tunneling microscopy (ESR-STM). Using two titanium atoms on a MgO/Ag(100) substrate as a model, we construct a two-qubit system whose dynamics are coherently manipulated through tailored microwave pulse sequences. We generate Bell states by implementing a Hadamard gate followed by a controlled-NOT gate, and evaluate its fidelity and concurrence using the quantum-master equation-based code TimeESR. Our results demonstrate that ESR-STM can create entangled states with significant fidelity. This study paves the way for the realization of atom-based quantum circuits and highlights ESR-STM as a powerful tool for probing and engineering entangled states on surfaces.