Loss' research concerns the quantum theory of condensed-matter- and solid-state physics. In particular, he studies spin- and charge-effects in semiconducting and magnetic nanostructures. He is one of the leading theorists investigating the realization of quantum information processing protocols in semiconductor structures. His 1998 paper (jointly with David DiVincenzo) proposing the use of spin qubits in semiconductor quantum dots is the foundation of one of the main approaches towards the realization of a quantum computer and (as of 2018) has been cited more than 6000 times. Further lines of research include decoherence, nuclear spin physics, topological matter, Majorana fermions and parafermions.