  We report a proof-of-principle experiment for a new method of temperature
measurements in waveguide quantum electrodynamics (wQED) experiments, allowing
one to differentiate between global and local baths. The method takes advantage
of collective states of two transmon qubits located in the center of a
waveguide. The Hilbert space of such a system forms two separate subspaces
(bright and dark) which are coupled differently to external noise sources.
Measuring transmission through the waveguide allows one to extract separately
the temperatures of the baths responsible for global and local excitations in
the system. Such a system would allow for building a new type of primary
temperature sensor capable of distinguishing between local and global baths.
