Ligand Radicals as Modular Organic Electron Spin Qubits.

Area of Science:

• Coordination Chemistry
• Quantum Computing Materials
• Molecular Spintronics

Background:

• Traditional coordination complexes utilize metal ions as the primary site for spin properties.
• Molecular electron spin qubits require stable spin centers with long coherence times for quantum information processing.

Purpose of the Study:

• To explore the intrinsic redox activity of dithiolene ligands as a novel spin host in molecular electron spin qubits.
• To invert the traditional roles of metal and ligand in coordination complexes for qubit design.
• To investigate the spin dynamics and coherence properties of ligand radical spin centers.

Main Methods:

• Synthesis of paramagnetic bis(dithiolene) complexes with group 10 metals (Ni, Pd, Pt).
• Pulsed Electron Paramagnetic Resonance (EPR) spectroscopy to probe spin dynamics.
• Temperature-dependent measurements of phase memory time (T_M) and spin-lattice relaxation time (T₁).

Main Results:

• The dithiolene ligand radical acts as an effective spin host, demonstrating the inverted role concept.
• Phase memory times (T_M) are influenced by the diamagnetic metal ion, with platinum complexes showing shorter times.
• Short T_M in platinum complexes correlate with diminished spin-lattice relaxation (T₁) due to strong spin-orbit coupling.
• The molecular qubit prototype achieved one of the longest phase memory times recorded for such systems.

Conclusions:

• The intrinsic redox activity of dithiolene ligands can be harnessed as a primary spin host in molecular qubits.
• Metal-ligand role inversion offers a new strategy for designing molecular spin qubits with tunable properties.
• The developed molecular qubit prototype shows significant potential for quantum computing applications due to its long coherence times.