  We discuss the non-zero frequency noise of heat current with the explicit
example of energy carried by thermal photons in a circuit. Instead of the
standard circuit modelling that gives a convenient way of predicting
time-averaged heat current, we describe a setup composed of two resistors
forming the heat baths by collections of bosonic oscillators. In terms of
average heat transport this model leads to identical results with the
conventional one, but besides this, it yields a convenient way of dealing with
noise as well. The non-zero frequency heat current noise does not vanish in
equilibrium even at zero temperature, the result that is known for, e.g.,
electron tunneling. We present a modulation method that can convert the
difficult-to-measure high frequency quantum noise down to zero frequency.
