Reversing the direction of heat flow using quantum correlations

Understand

Heat spontaneously flows from hot to cold in standard thermodynamics.

• However, the latter theory presupposes the absence of initial correlations between interacting systems.
• We here experimentally demonstrate the reversal of heat flow for two quantum correlated spins-1/2, initially prepared in local thermal states at different effective temperatures, employing a Nuclear Magnetic Resonance setup.
• We observe a spontaneous energy flow from the cold to the hot system.