Convergence guarantees for discrete mode approximations to non-Markovian quantum baths
The paper rigorously proves that approximating non-Markovian quantum environments with a finite number of discrete modes—using methods like Lorentzian pseudomodes or star-to-chain transformations—guarantees convergence to the true dynamics. This holds under specific physical conditions, ensuring that the error in simulating complex open quantum systems decreases predictably as more modes are included.