Clock-work trade-off relation for coherence in quantum thermodynamics

Understand

In thermodynamics, quantum coherences - superpositions between energy eigenstates - behave in distinctly nonclassical ways.

• Recently mathematical frameworks have emerged to account for these features and have provided a range of novel insights.
• Here we describe how thermodynamic coherence splits into two kinds - "internal" coherence that admits an energetic value in terms of thermodynamic work, and "external" coherence that does not have energetic value, but instead corresponds to the functioning of the system as a quantum clock.
• For the latter form of coherence we provide dynamical constraints that relate to quantum metrology and macroscopicity, while for the former, we show that quantum states exist that have finite internal coherence yet with zero deterministic work value.