Anomalous heat flow and quantum Otto cycle with indefinite causal order

• URL: http://arxiv.org/abs/2511.04028v2
• Date: Fri, 07 Nov 2025 02:26:56 GMT
• Title: Anomalous heat flow and quantum Otto cycle with indefinite causal order
• Authors: Qing-Feng Xue, Qi Zhang, Xu-Cai Zhuang, Yun-Jie Xia, Enrico Russo, Giulio Chiribella, Rosario Lo Franco, Zhong-Xiao Man,
• Abstract summary: We show that when the order of interactions between two identical thermalization channels is indefinite, an anomalous heat flow emerges.<n>We design a quantum Otto cycle with indefinite causal order, which not only achieves refrigeration but also generates work.<n>The anomalous heat flow and the quantum Otto cycle are experimentally simulated in a photonic quantum setup.
• Score: 5.369208287833849
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: The principle that heat spontaneously flows from higher temperature to lower temperature is a cornerstone of classical thermodynamics, often assumed to be independent of the sequence of interactions. While this holds true for macroscopic systems at equilibrium, here we show that, when the order of interactions between two identical thermalization channels is indefinite, an anomalous heat flow emerges, whereby heat can sometime flow from a colder entity to a hotter one. Taking advantage of this anomalous heat flow, we design a quantum Otto cycle with indefinite causal order, which not only achieves refrigeration but also generates work. The anomalous heat flow and the quantum Otto cycle are experimentally simulated in a photonic quantum setup, which provides a proof-of-principle demonstration of the theory.

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