A thermodynamic approach to measuring entropy in a few-electron nanodevice

Abstract: The entropy of a system gives a powerful insight into its microscopic degrees of freedom, however standard experimental ways of measuring entropy through heat capacity are hard to apply in mesoscale and nanoscale systems, as they require the measurement of increasingly small amounts of heat. This problem calls for radically different measurement methods that do not suffer from decreasing accuracy with the decreasing size of the system. For nanoelectric devices in the state of Coulomb blockade, with only two energetically accessible charge states, two purely electric, size-independent methods of measuring the entropy difference between the charge states have been proposed: through transport properties and charge balance measurements. We suggest a self-consistent thermodynamic framework for the treatment of entropy in Coulomb-blocked electric nanodevices which incorporates both existing entropy measurement methods, generalises them, and expands to systems with arbitrarily complex microstates corresponding to each charge state.