Quantum algorithms for Schrieffer-Wolff transformation

The Schrieffer-Wolff transformation aims to solve degenerate perturbation problems and give an effective Hamiltonian that describes the low-energy dynamics of exact in subspace unperturbed Hamiltonian. This unitary decoupling high-energy subspaces for transformed can be realized by quantum circuits. We a fully algorithm realizing SW transformation. also propose hybrid quantum-classical finding on NISQ hardware, where general cost function is used indicate degree. Numerical simulations without or with noise experiments computer ibmq_manila are implemented Heisenberg chain model. Our results verify show its validity near-term computers.