Quantum computation with classical light: The Deutsch Algorithm

•We implement the Deutsh Algorithm using linear optical elements and classical light.•Our qubits are encoded in the polarisation and orbital angular momentum of the beam.•We show that it is possible to achieve quantum computation with two qubits in the classical domain of light.

We present an implementation of the Deutsch Algorithm using linear optical elements and laser light. We encoded two quantum bits in form of superpositions of electromagnetic fields in two degrees of freedom of the beam: its polarisation and orbital angular momentum. Our approach, based on a Sagnac interferometer, offers outstanding stability and demonstrates that optical quantum computation is possible using classical states of light.