Heterodimetallic [LnLn′] Lanthanide Complexes: Toward a Chemical Design of Two-Qubit Molecular Spin Quantum Gates

A major
challenge for realizing quantum computation is finding
suitable systems to embody quantum bits (qubits) and quantum gates
(qugates) in a robust and scalable architecture. An emerging bottom-up
approach uses the electronic spins of lanthanides. Universal qugates
may then be engineered by arranging in a molecule two interacting
and different lanthanide ions. Preparing heterometallic
lanthanide species is, however, extremely challenging. We have discovered
a method to obtain [LnLn′] complexes with the appropriate requirements.
Compound [CeEr] is deemed to represent an ideal situation. Both ions
have a doubly degenerate magnetic ground state and can be addressed
individually. Their isotopes have mainly zero nuclear spin, which
enhances the electronic spin coherence. The analogues [Ce2], [Er2], [CeY], and [LaEr] have also been prepared to
assist in showing that [CeEr] meets the qugate requirements, as revealed
through magnetic susceptibility, specific heat, and EPR. Molecules
could now be used for quantum information processing.