Modeling Phonon-Induced Decoherence in Solid-State Defect based Qubits

Systems that serve as quantum memories are crucial to tasks in quantum information processing, computing, and communication. Decoherence of the electronic spin qubits in solid state defect centers have been studied extensively in experiments and methodologies have been developed to estimate spin decoherence rates. We model the effect of decoherence caused by spin-phonon coupling in these systems, with a special focus on the evolution of the entangled state of two spin qubits that were entangled using a heralded photonic Bell swap. Our model predicts the initial Fidelity and the decay rate of distillable entanglement, which is corroborated by experimentally observed decoherence time scales. Extending our model to include other decoherence mechanisms, e.g., via hyperfine coupling to neighboring nuclear spins, will pave the way to a predictive model for engineering artificial-atom qubits with desirable coherence properties.