Irreversibility of heat transport and optical non-coherence: an experimental demonstration of the analogy

Abstract

The arrow of time problem remains one of the most intriguing questions of modern physics. Weinvestigate one particular example of this problem: the irreversibility of heat transfer through aninterface between two materials. This special case turned out to be much simpler than that oftransport phenomena in bulk materials. We start by exploring a mechanism that turns equations ofreversible, unitary transmission of wave-particles through the interface into irreversible equations,describing the distribution functions at the interface. This mechanism, non-coherence, is treated inan analogy with wave optics: no real waves are absolutely monochromatic and thus have finitetemporal coherence. We find an experimental setup to prove the suggested mechanism and calculatethe optimal parameters to observe the phenomenon. We conduct an experiment whose results fullyagree with the predictions of our theory. In the final discussion, we revisit the connection with heattransport through a material interface and show that only the suggested mechanism can explain theirreversibility of interfacial transport.