How to measure entropy in mesoscopic systems

Entropy is a key characteristic of states of matter, but its measurement is typically limited to bulk systems. For this reason measurements of nontrivial entropy signatures reflecting correlations and frustration in various exotic excitations in condensed matter systems, such as Kondo impurities and Majorana states, have remained elusive. In this talk I will discuss recent experimental progress in measuring entropy in mesoscopic systems, using charge sensors of quantum dot type systems combined with thermodynamic Maxwell relations. I will show some encouraging experimental results opening the door for novel entropic probes, along with experimental puzzles.