Single-spin detection by qubit SWAP to a molecular nanomagnet

Spin state detection is a key but very challenging step for any spin-based solid-state quantum computing technology. In fullerene-based quantum computer technologies, we here propose to detect the single spin inside a fullerene by transferring the quantum information from the endohedral spin to the ground states of a molecular nanomagnet Fe₈, with large spin S = 10. We show how to perform the required SWAP operation and how to read out the information through state-of-the-art techniques such as micro-SQUID.