arXiv:1702.05161 · Proceedings of the National Academy of Sciences
Observing a quantum Maxwell demon at work
Nathanaël Cottet, S. Jézouin, Landry Bretheau, Philippe Campagne-Ibarcq, Quentin Ficheux, Janet Anders, Alexia Auffèves, Rémi Azouit, Pierre Rouchon, Benjamin Huard
In apparent contradiction to the laws of thermodynamics, Maxwell's demon is able to cyclically extract work from a system in contact with a thermal bath, exploiting the information about its microstate. The resolution of this paradox required the insight that an intimate relationship exists between information and thermodynamics. Here, we realize a Maxwell demon experiment that tracks the state of each constituent in both the classical and quantum regimes. The demon is a microwave cavity that encodes quantum information about a superconducting qubit and converts information into work by powering up a propagating microwave pulse by stimulated emission. Thanks to the high level of control of superconducting circuits, we directly measure the extracted work and quantify the entropy remaining in the demon's memory. This experiment provides an enlightening illustration of the interplay of thermodynamics with quantum information.
In apparent contradiction to the laws of thermodynamics, Maxwell's demon is able to cyclically extract work from a system in contact with a thermal bath, exploiting the information about its microstate. The resolution of this paradox required the insight that an intimate relationship exists between information and thermodynamics. Here, we realize a Maxwell demon experiment that tracks the state of each constituent in both the classical and quantum regimes. The demon is a microwave cavity that encodes quantum information about a superconducting qubit and converts information into work by powering up a propagating microwave pulse by stimulated emission. Thanks to the high level of control of superconducting circuits, we directly measure the extracted work and quantify the entropy remaining in the demon's memory. This experiment provides an enlightening illustration of the interplay of thermodynamics with quantum information.
This article develops an expanded critical–propositional analysis of Nathanaël Cottet and collaborators’ 2017 experiment, “Observing a Quantum Maxwell Demon at Work,” in systematic dialogue with the Theory of Objectivity (TO), developed by Vidamor Cabannas and Denivaldo Silva. Cottet et al. experimentally realized a quantum Maxwell demon using superconducting circuits. A transmon qubit served as the thermodynamic system, a microwave cavity functioned as the demon’s quantum memory, and a propagating microwave field acted as the battery into which work was deposited by stimulated emission (Cottet et al. 2017). The experiment directly measured extracted work while reconstructing the energy and entropy of both system and memory. Crucially for the present inquiry, the amount of information physically encoded in the memory affected the sign and magnitude of the subsequently extracted work. An efficiently informed demon could extract positive work, whereas an ignorant demon could allow the system to drain energy from the battery. The experiment further demonstrated entropy transfer from the system to the memory and, for coherent initial quantum states, the transfer of nonclassical coherence to the memory. Cottet et al. therefore provide unusually explicit experimental evidence that physically instantiated information participates in measurable thermodynamic processes. The analysis employs a strict epistemological hierarchy. First, experimentally observed facts are distinguished from theoretical interpretations. Second, structural compatibility between those facts and categories of TO is distinguished from empirical confirmation of TO-specific claims. Third, theory-specific corroboration is reserved for cases in which a derived prediction could discriminate TO from rival frameworks. Finally, the modal necessity claimed for the axioms of TO is distinguished from contingent experimental confirmation. Under this discipline, the Cottet experiment exhibits substantial structural compatibility with TO’s fourth, fifth, sixth, and especially seventh Absolute Truths: boundary, relational observation, composition from antecedent elements, and the tran- scendent informational element. The experiment is particularly relevant to the TO hypothesis that knowledge or information generated in atomic relations is physically associated with atomic radiation, because the demon’s information is encoded in elec- tromagnetic degrees of freedom and subsequently affects microwave stimulated emission and work extraction. Nevertheless, the experiment does not establish the stronger ontological identity between information and atomic radiation proposed by TO, nor does it test logical Nothingness, infinity, the cosmogenic theorem, or the cosmological Eras. A propositional interpretation is also developed in terms of the Inductive Effects of TO. Information encoding and stabilization may be treated as an operational analogue of reductive or convergent organization, while stimulated emission and outward propagation of electro- magnetic energy may be treated as an operational analogue of expansive manifestation. The article concludes that Cottet et al. provide significant but indirect empirical support for a set of operational bridges relevant to TO: information has physical efficacy; information can be stored in radiation-bearing quantum degrees of freedom; relations establish physically consequential correlations; memory modifies future dynamics; and informational organization is inseparable from entropy and energetic accounting. These results do not uniquely confirm TO, but they identify a particularly fertile empirical domain for its further operationalization and discriminating tests. Keywords: Theory of Objectivity; quantum Maxwell demon; quantum information; quantum thermodynamics; superconducting circuits; Maxwell’s demon; Landauer prin- ciple; information; radiation; stimulated emission; quantum memory; modal necessity; Inductive Effects; phenomenic elements; empirical corroboration.
This article develops an expanded critical–propositional analysis of Nathanaël Cottet and collaborators’ 2017 experiment, “Observing a Quantum Maxwell Demon at Work,” in systematic dialogue with the Theory of Objectivity (TO), developed by Vidamor Cabannas and Denivaldo Silva. Cottet et al. experimentally realized a quantum Maxwell demon using superconducting circuits. A transmon qubit served as the thermodynamic system, a microwave cavity functioned as the demon’s quantum memory, and a propagating microwave field acted as the battery into which work was deposited by stimulated emission (Cottet et al. 2017). The experiment directly measured extracted work while reconstructing the energy and entropy of both system and memory. Crucially for the present inquiry, the amount of information physically encoded in the memory affected the sign and magnitude of the subsequently extracted work. An efficiently informed demon could extract positive work, whereas an ignorant demon could allow the system to drain energy from the battery. The experiment further demonstrated entropy transfer from the system to the memory and, for coherent initial quantum states, the transfer of nonclassical coherence to the memory. Cottet et al. therefore provide unusually explicit experimental evidence that physically instantiated information participates in measurable thermodynamic processes. The analysis employs a strict epistemological hierarchy. First, experimentally observed facts are distinguished from theoretical interpretations. Second, structural compatibility between those facts and categories of TO is distinguished from empirical confirmation of TO-specific claims. Third, theory-specific corroboration is reserved for cases in which a derived prediction could discriminate TO from rival frameworks. Finally, the modal necessity claimed for the axioms of TO is distinguished from contingent experimental confirmation. Under this discipline, the Cottet experiment exhibits substantial structural compatibility with TO’s fourth, fifth, sixth, and especially seventh Absolute Truths: boundary, relational observation, composition from antecedent elements, and the tran- scendent informational element. The experiment is particularly relevant to the TO hypothesis that knowledge or information generated in atomic relations is physically associated with atomic radiation, because the demon’s information is encoded in elec- tromagnetic degrees of freedom and subsequently affects microwave stimulated emission and work extraction. Nevertheless, the experiment does not establish the stronger ontological identity between information and atomic radiation proposed by TO, nor does it test logical Nothingness, infinity, the cosmogenic theorem, or the cosmological Eras. A propositional interpretation is also developed in terms of the Inductive Effects of TO. Information encoding and stabilization may be treated as an operational analogue of reductive or convergent organization, while stimulated emission and outward propagation of electro- magnetic energy may be treated as an operational analogue of expansive manifestation. The article concludes that Cottet et al. provide significant but indirect empirical support for a set of operational bridges relevant to TO: information has physical efficacy; information can be stored in radiation-bearing quantum degrees of freedom; relations establish physically consequential correlations; memory modifies future dynamics; and informational organization is inseparable from entropy and energetic accounting. These results do not uniquely confirm TO, but they identify a particularly fertile empirical domain for its further operationalization and discriminating tests. Keywords: Theory of Objectivity; quantum Maxwell demon; quantum information; quantum thermodynamics; superconducting circuits; Maxwell’s demon; Landauer prin- ciple; information; radiation; stimulated emission; quantum memory; modal necessity; Inductive Effects; phenomenic elements; empirical corroboration.
Information thermodynamics bridges information theory and statistical physics by connecting information content and entropy production through measurement and feedback control. Maxwell's demon is a hypothetical character that uses information about a system to reduce its entropy. Here we realize a Maxwell's demon acting on a superconducting quantum circuit. We implement quantum non-demolition projective measurement and feedback operation of a qubit and verify the generalized integral fluctuation theorem. We also evaluate the conversion efficiency from information gain to work in the feedback protocol. Our experiment constitutes a step toward experimental studies of quantum information thermodynamics in artificially made quantum machines.
Information is usually treated as something we use to describe the physical world. In modern physics, however, there is growing evidence that information itself behaves like a physical resource, subject to the same laws that govern energy, heat, and matter. This paper develops that perspective through a concrete experimental proposal we call Quantum Maxwell Demon Arrays (QMDA)—systems that use measurement and feedback at the quantum scale to convert information about a system into controlled physical work. Building on established results such as the Landauer bound and the Szilard engine, we show that information acquired through measurement can be converted into usable free energy, provided that its physical costs and constraints are properly accounted for. In QMDA, measurements are not passive observations but active physical interactions whose outcomes can be stored, processed, and exploited thermodynamically. Organized into arrays, these measurement–feedback units act collectively, allowing information flow itself to shape energy extraction, entropy production, and system control. We demonstrate how QMDA can serve as experimental probes of information thermodynamics, enabling direct tests of how information constrains and enables physical processes in quantum regimes. This framework clarifies the status of measurement as a physical operation rather than a subjective act of interpretation, and it suggests new pathways toward ultra-efficient computation, precision sensing, and energy management within known thermodynamic limits. More broadly, this work supports the view that information is not merely a bookkeeping device for observers, but a fundamental ingredient of physical dynamics—one that can be quantified, manipulated, and transformed into free energy under well-defined physical rules.
Maxwell's demon explores the role of information in physical processes.Employing information about microscopic degrees of freedom, this "intelligent observer" is capable of compensating entropy production (or extracting work), apparently challenging the second law of thermodynamics.In a modern standpoint, it is regarded as a feedback control mechanism and the limits of thermodynamics are recast incorporating information-to-energy conversion.We derive a trade-off relation between information-theoretic quantities empowering the design of an efficient Maxwell's demon in a quantum system.The demon is experimentally implemented as a spin-1=2 quantum memory that acquires information, and employs it to control the dynamics of another spin-1=2 system, through a natural interaction.Noise and imperfections in this protocol are investigated by the assessment of its effectiveness.This realization provides experimental evidence that the irreversibility in a nonequilibrium dynamics can be mitigated by assessing microscopic information and applying a feed-forward strategy at the quantum scale.
Maxwell's demon explores the role of information in physical processes. Employing information about microscopic degrees of freedom, this "intelligent observer" is capable of compensating entropy production (or extracting work), apparently challenging the second law of thermodynamics. In a modern standpoint, it is regarded as a feedback control mechanism and the limits of thermodynamics are recast incorporating information-to-energy conversion. We derive a trade-off relation between information-theoretic quantities empowering the design of an efficient Maxwell's demon in a quantum system. The demon is experimentally implemented as a spin-1/2 quantum memory that acquires information, and employs it to control the dynamics of another spin-1/2 system, through a natural interaction. Noise and imperfections in this protocol are investigated by the assessment of its effectiveness. This realization provides experimental evidence that the irreversibility in a nonequilibrium dynamics can be mitigated by assessing microscopic information and applying a feed-forward strategy at the quantum scale.