Stochastic Energetics of Brownian Heat Engines in a Passive and Active Heat Bath( II )

The efficiency of the heat engine is a central theme in thermodynamics. Advancein theories to describe dynamics and technologies to manipulate a colloidalparticle allows us to demonstrate the micron-sized heat engine in the colloidalsystem over the past decade. However, why the efficiency in the active bathsurpasses the maximal bound or whether the thermal ratchet can attain theCarnot limit are remained challenging due to the difficulty to produce controllablepotential and temperature. In the previous study, we successfully developed theappropriate tool to answer these questions, called the optical feedback trap whichcan create arbitrary spatiotemporal potential and produce the random noises(considered as temperature) at the destination where we desire by the feedbackprocess. Here, we propose the experiments of the Brownian heat engines thatare possible only with the feedback trap.The following is an overview of the proposed research plan. (i) We willdemonstrate the Brownian Carnot engine in the active heat bath with the wellcontrollable artificial noise-generating system. It is known that the efficiency in theactive bath exceeds the Carnot efficiency. We will find out what characteristics ofnoises affect the efficiency of the engine and compare it to the results from thereal bacterial bath. (ii) We will experimentally realize the Büttiker-Landauerratchet whose efficiency is controversial and needed to be experimentallyconfirmed if the Carnot efficiency can be achievable. The optimal potential formaximum power will also be studied.