Spin decoherence in molecular crystals: Nuclear vs electronic spin baths.

Area of Science:

• Quantum Information Science
• Molecular Spin Dynamics
• Spectroscopy

Background:

• Decoherence, the loss of quantum phase information, limits molecular qubit performance.
• Both electron-spin and nuclear-spin interactions contribute to decoherence at low temperatures.
• Uncertainty persists regarding the dominant decoherence mechanism across various experimental conditions.

Purpose of the Study:

• To quantitatively identify the primary decoherence mechanism in molecular qubits.
• To explore strategies for prolonging coherence times in molecular spin systems.
• To assess the potential of molecular qubits for quantum information processing.

Main Methods:

• Utilized the cluster-correlation expansion (CCE) method for theoretical simulations.
• Modeled decoherence in two prototypical molecular qubits.
• Investigated the impact of electron and nuclear spin concentrations on coherence.

Main Results:

• Nuclear spins emerge as the dominant decoherence source below approximately 1 mM electron spin concentration.
• Deuterated samples show potential for achieving ~0.1 ms coherence times at ~0.1 mM electron spin concentration.
• Dynamical decoupling in hydrogen-rich molecular crystals can yield 10 ms coherence times for electron spin concentrations below 1 mM.

Conclusions:

• Nuclear spin interactions are critical for understanding and mitigating decoherence in molecular qubits.
• Deuteration and dynamical decoupling are promising techniques for enhancing molecular qubit coherence.
• Molecular spins hold significant untapped potential for advancing quantum technologies.