  Secret key exchange relies on the creation of correlated signals, serving as
the raw resource for secure communication. Thermal states, exhibit Hanbury
Brown and Twiss correlations, which offer a promising avenue for generating
such signals. In this paper, we present an experimental implementation of a
central broadcast thermal state quantum key distribution (QKD) protocol in the
microwave region. Our objective is to showcase a straightforward method of QKD
utilizing readily available broadcasting equipment. Unlike conventional
approaches to thermal state QKD, we leverage displaced thermal states. These
states enable us to share the output of a thermal source among Alice, Bob, and
Eve via both waveguide channels and free space. Through measurement and
conversion into bit strings, our protocol produces key-ready bit strings
without the need for specialized equipment. By harnessing the inherent noise in
thermal broadcasts, our setup facilitates the recovery of distinct bit strings
by all parties involved.
