Entropy flow in quantum heat engines

Mohammad H. Ansari, Yuli V. Nazarov

We evaluate R\'enyi entropy flows from generic quantum heat engines (QHE) to a weakly coupled probe environment kept in thermal equilibrium. We show that the flows are determined not only by heat flow but also by a quantum coherent flow that can be separately measured in experiment apart from the heat flow measurement. The same pertains to Shannon entropy flow. This appeals for a revision of the concept of entropy flows in quantum nonequlibrium thermodynamics.

T. E. Humphrey, R. Newbury, Richard P. Taylor +1 more

Mohammad H. Ansari

Entropy is one of the central quantities in thermodynamics, whose flow between two systems determines the statistics of energy transfers. In quantum systems entropy is non-linear in density matrix whose time evolution is cumbersome. Using recent developments in the Keldysh formalism for the evolution of nonlinear quantum information measures (Phys. Rev. B 91, 174307 (2015)), we study the flow of von Neumann and Renyi entropies in a generic four-level quantum system that is weakly coupled to equilibrium heat engines. We show that noise-induced coherence has significant influence on the entropy flow of the quantum heat engine. We determine analytical optimization of couplings for the purpose of designing optimal artificial energy transfer systems.

Mohammad H. Ansari, Yuli V. Nazarov

Brent W. Jonah

We demonstrate that entropy-optimized control protocols inspired by Quantum Heat Engine (QHE) cycles robustly reduce the Lyapunov exponent (quantum chaos rate) by ~42% in chaotic quantum systems. Comprehensive validation confirms the effect across system sizes (N=6-12), 50 independent trials (100% consistency), and multiple unitary types. We derive t_emergent = S/σ from Page-Wootters and Landauer principles, predicting that emergent time flow is proportional to entropy production rate. QHE-modified Page-Wootters simulation confirms ω_QHE/ω_standard = 0.6002. Direct entropy measurement validates the derivation causally: ΔS_QHE/ΔS_standard = 0.6000, matching the frequency ratio within 0.03%. These results establish that thermodynamic control of entropy production directly controls emergent time flow, providing the first numerical demonstration that time's flow rate can be modified via entropy management. Key results:• 42% Lyapunov suppression (λ ratio = 0.58)• Page-Wootters clock slowing (ω ratio = 0.6002)• Causal validation (entropy ratio = 0.6000)• Derived relationship: t_emergent = S/σ

Sangchul Oh, Sabre Kais