Phase-Tunable Thermal Logic: Computation with Heat

Boolean algebra, the branch of mathematics in which variables can assume only true or false values, is the theoretical basis of classical computation. The analogy between Boolean operations and electronic switching circuits, highlighted by Shannon in 1938, paved the way for modern computation based on electronic devices. The growth in the computational power of such devices, after an exciting exponential - Moore's trend - is nowadays blocked by heat dissipation due to computational tasks, which are very demanding due to the miniaturization of chips. Heat is often a detrimental form of energy which increases the system's entropy, decreasing the efficiency of logic operations. Here, we propose a physical system that is able to perform thermal-logic operations by reversing the old heat-disorder epitome into a heat-order paradigm. We lay the foundations of heat computation by encoding logic state variables in temperature and introducing the thermal counterparts of electronic logic gates. Exploiting quantum effects in thermally biased Josephson junctions (JJs), we propound a possible realization of a functionally complete logic. Our architecture ensures high operational stability and robustness, with switching frequencies reaching the GHz range.