  Electron quantum optics aims to realize ideas from the quantum theory of
light with the role of photons being played by charge pulses in electronic
conductors. Experimentally, the charge pulses are excited by time-dependent
voltages, however, one could also generate heat pulses by heating and cooling
an electrode. Here, we explore this intriguing idea by formulating a Floquet
scattering theory of heat pulses in mesoscopic conductors. The adiabatic
emission of heat pulses leads to a heat current that in linear response is
given by the thermal conductance quantum. However, we also find a
high-frequency component, which ensures that the fluctuation-dissipation
theorem for heat currents, whose validity has been debated, is fulfilled. The
heat pulses are uncharged, and we probe their electron-hole content by
evaluating the partition noise in the outputs of a quantum point contact. We
also employ a Hong--Ou--Mandel setup to examine if the pulses bunch or
antibunch. Finally, to generate an electric current, we use a Mach--Zehnder
interferometer that breaks the electron-hole symmetry and thereby enables a
thermoelectric effect. Our work paves the way for systematic investigations of
heat pulses in mesoscopic conductors, and it may stimulate future experiments.
