Direct Nuclear-Level Qubits using Trapped Th-229 Ions: A Platform for Entanglement and Universal Quantum Information Processing

TL;DR

This paper proposes using trapped Th-229 ions as nuclear-level qubits for quantum computing, demonstrating theoretically that high-fidelity entanglement can be achieved through phonon-mediated interactions, leveraging the nucleus's long coherence times.

Contribution

It introduces a theoretical framework for nuclear qubits in Th-229 ions, enabling coherent control and entanglement with realistic experimental parameters.

Findings

High-fidelity nuclear entanglement is feasible with current technology.

Phonon-mediated coupling enables entanglement between nuclear states.

Long nuclear coherence times enhance quantum information processing potential.

Abstract

The low-energy isomeric transition in Thorium-229 offers a unique interface between nuclear and atomic physics, presenting a resource for quantum technologies that is notably resilient to environmental decoherence. While early experiments focused on nuclei in solid-state crystals, the recent advent of a continuous-wave vacuum ultraviolet laser at 148.4~nm now enables direct coherent control of individual trapped Th-229 ions. Building on this breakthrough, we present a theoretical framework for utilizing trapped Th-229^{3+} ions as high-fidelity nuclear-level qubits, wherein quantum state preparation, single-qubit control, and entangling operations based on nuclear energy levels can all be efficiently realized. We analyze a scheme to generate entanglement between the nuclear isomeric states of two ions through phonon-mediated coupling, driven by optimized red- and blue-detuned laser sideband pulses. Our analysis, grounded in realistic experimental parameters, also demonstrates that high-fidelity entanglement is achievable, leveraging the nucleus's intrinsically long coherence times. These results provide a practical roadmap for developing nuclear-based quantum information processors and suggest that entangled nuclear-level qubits could potentially unlock new frontiers in precision metrology.