Decoherence in Molecular Electron Spin Qubits: Insights from Quantum Many-Body Simulations

Area of Science:

• Quantum Information Science
• Molecular Magnetism
• Condensed Matter Physics

Background:

• Quantum states rely on wave function phases for effects like interference and entanglement.
• Decoherence, the loss of relative phase information due to environmental interactions, hinders quantum computing.
• Understanding decoherence in molecular systems is crucial for developing molecular spin qubits.

Purpose of the Study:

• To theoretically investigate decoherence in an isolated molecule, specifically a central electron spin qubit interacting with nuclear spins.
• To identify and characterize residual coherence and its dependence on molecular properties and proximity.
• To establish residual coherence as a potential descriptor for coherence in magnetic molecules.

Main Methods:

• Theoretical study of a central electron spin qubit interacting with nearby nuclear spins in magnetic molecules.
• Analysis of decoherence mechanisms within an isolated molecular system.
• Investigation of the influence of nearby molecules on decoherence, considering their separation distance.

Main Results:

• Decoherence was shown to occur even in an isolated molecule, with not all phase information being lost.
• Residual coherence was found to be molecule-dependent and provides a microscopic explanation for experimental observations.
• The contribution of nearby molecules to decoherence exhibits a complex dependence on separation, peaking at intermediate distances.

Conclusions:

• Residual coherence can be calculated simply and correlates well with coherence time, serving as a descriptor for magnetic molecules.
• This research provides design principles for enhancing coherence in molecular spin qubits.
• The findings motivate further theoretical and experimental work on decoherence in molecular systems.