  Modern thermodynamic theories can be used to study highly complex quantum
dynamics. Here, we experimentally demonstrate that the violation of
thermodynamic constraints allows to detect the coupling of a quantum system to
a hidden environment. By using the IBM quantum superconducting processors, we
perform thermodynamic tests to detect a qubit environment interacting with a
system composed of up to four qubits. The experiments are complemented by
theoretical findings that show efficient scalability of the tests with respect
to system size. Hence, they may be useful to detect an open system dynamics in
situations where other methods (e.g. quantum state tomography) are practically
infeasible.
