Electronic spins in paramagnetic coordination complexes offer enormous promise as qubits, the fundamental unit of quantum information processing (QIP). However, the implementation of these complexes is hampered by their short-lived superposition states, rendering the complexes unsuitable for long computational processes. Fundamental design principles governing the lifetimes of these superposition states, or coherence times, must be elucidated to rationally design device-ready qubits. To do so, we utilize synthetic coordination chemistry to investigate structural and electronic effects that contribute to coherence time. We devise two separate series of vanadium(IV) complexes with nuclear spin-free ligand fields, a key requirement as nuclear spins are a major contributor to the collapse of the superposition state, or decoherence. Between the two series, there are two key distinctions: (1) the substitution of a ligand with a vanadium-oxo moiety and (2) different electronic structures. We investigated these complexes using pulsed electron paramagnetic resonance spectroscopy to assess the impact of these differences on the coherence times in these electronic spin-based molecular qubits. The results from our study demonstrate molecular polarity and ligand bulk as two key design parameters to suppress thermal processes and eliminate environmental nuclear spins that contribute to decoherence.

Coordination chemistry approaches for rational vanadium(IV) qubit design

253rd National Meeting (2017)

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