  We experimentally probe the interplay of the quantum switch with the laws of
thermodynamics. The quantum switch places two channels in a superposition of
orders and may be applied to thermalizing channels. Quantum-switching thermal
channels has been shown to give apparent violations of the second law. Central
to these apparent violations is how quantum switching channels can increase the
capacity to communicate information. We experimentally show this increase and
how it is consistent with the laws of thermodynamics, demonstrating how
thermodynamic resources are consumed. We use a nuclear magnetic resonance
approach with coherently controlled interactions of nuclear spin qubits. We
verify an analytical upper bound on the increase in capacity for channels that
preserve energy and thermal states, and demonstrate that the bound can be
exceeded for an energy-altering channel. We show that the switch can be used to
take a thermal state to a state that is not thermal, whilst consuming free
energy associated with the coherence of a control system. The results show how
the switch can be incorporated into quantum thermodynamics experiments as an
additional resource.
