We consider steady state heat conduction across a quantum harmonic chain
connected to reservoirs modelled by infinite collection of oscillators. The
heat, Q, flowing across the oscillator in a time interval τ is a
stochastic variable and we study the probability distribution function P(Q).
In the large τ limit we use the formalism of full counting statistics
(FCS) to compute the generating function of P(Q) exactly. We show that P(Q)
satisfies the steady state fluctuation theorem (SSFT) regardless of the
specifics of system, and it is nongaussian with clear exponential tails. The
effect of finite τ and nonlinearity is considered in the classical limit
through Langevin simulations. We also obtain predictions of universal heat
current fluctuations at low temperatures in clean wires.Comment: 4 pages, 2 figure