Investigation of High-Symmetry Lanthanide Complexes as Molecular Spin Qubits

Eduardo Hernandez Requejo, Michael Shatruk

Florida State University

A quantum bit (qubit) is the fundamental unit of quantum information processing that relies on a superposition of two quantum states, a|0⟩+ b|1⟩. Molecular electron spin qubits (MESQs) offer the advantage of high synthetic tunability but suffer from rapid decoherence, i.e., the loss of the superposition state. Clock transitions, which emerge as energy gaps due to avoided crossing of electronic states, offer a viable pathway to achieve longer coherence times by decreasing the qubit’s sensitivity to the surrounding magnetic noise. Such transitions can be designed rationally by matching the rotational symmetry of lanthanide complexes to the |m_J| value of the ground state doublet generated by crystal-field splitting. To that end, we are exploring mono- and dinuclear complexes of lanthanide ions with integer-value total angular momenta (J). The high-symmetry coordination environment is achieved using tetradentate phthalocyanine and porphyrin ligands combined with mono- or bidentate ancillary ligands. The synthesis of dinuclear lanthanide complexes will allow the physical realization of two-qubit systems, including the control over the inter-qubit coupling by a light- or redox-sensitive linker, which the goal of implementing two-qubit logic gates.