Numerical modeling of the central spin problem using the spin-coherent-state representation.

Area of Science:

• Quantum mechanics
• Condensed matter physics
• Quantum information science

Background:

• Decoherence is a critical challenge in quantum systems, limiting their performance.
• Understanding decoherence in central spin systems interacting with a spin bath is essential for quantum technologies.
• Existing methods often struggle with nonperturbative decoherence regimes and large system sizes.

Purpose of the Study:

• To develop an efficient computational method for modeling spin-bath decoherence.
• To investigate nonperturbative decoherence regimes of a central spin.
• To enable controlled predictions for long-time decoherence in large quantum systems.

Main Methods:

• A mean-field-based method is developed for modeling spin-bath decoherence.
• The method utilizes the representation of the central spin density matrix.
• The approach is applied to systems with up to 16,000 bath spins.

Main Results:

• The developed method efficiently models spin-bath decoherence, including nonperturbative regimes.
• The approach is applicable to both longitudinal and transverse relaxation under various external fields.
• Controlled predictions for slow, long-time decoherence of the central spin are achieved for large quantum systems.

Conclusions:

• The efficient mean-field-based method provides a powerful tool for studying central spin decoherence.
• This work advances the understanding of decoherence in large quantum systems.
• The method facilitates accurate predictions for the long-term behavior of quantum information.