Three addressable spin qubits in a molecular single-ion magnet

TL;DR

This paper demonstrates that a single magnetic ion within a molecule can host multiple addressable spin qubits, enabling the development of more complex and noise-resistant quantum computing architectures.

Contribution

It introduces a method to encode multiple qubits in a single magnetic ion's electronic states, exemplified with a Gd(III) ion in a molecular environment.

Findings

Achieved coherent control of multiple spin states in a single ion.

Demonstrated the potential for universal three-qubit processing within a single molecule.

Showed feasibility of using molecular ions for scalable quantum computing.

Abstract

We show that several qubits can be integrated in a single magnetic ion, using its internal electronic spin states with energies tuned by a suitably chosen molecular environment. This approach is illustrated with a nearly-isotropic Gd(III) ion entrapped in a polyoxometalate molecule. Experiments with microwave technologies, either three dimensional cavities or quantum superconducting circuits, show that this magnetic molecule possesses the number of spin states and the set of coherently addressable transitions connecting these states that are needed to perform a universal three-qubit processor or, equivalently, a d=8-level 'qudit'. Our findings open prospects for developing more sophisticated magnetic molecules which can result in more powerful and noise resilient quantum computation schemes.