Dr KAY BRANDNER's Outputs (18)

Dynamics of microscale and nanoscale systems in the weak-memory regime: A mathematical framework beyond the Markov approximation (2025)
Journal Article
Brandner, K. (2025). Dynamics of microscale and nanoscale systems in the weak-memory regime: A mathematical framework beyond the Markov approximation. Physical Review E, 111(1), Article 014137. https://doi.org/10.1103/physreve.111.014137

The visible dynamics of small-scale systems are strongly affected by unobservable degrees of freedom, which can belong to either external environments or internal subsystems and almost inevitably induce memory effects. Formally, such inaccessible deg... Read More about Dynamics of microscale and nanoscale systems in the weak-memory regime: A mathematical framework beyond the Markov approximation.

Dynamics of microscale and nanoscale systems in the weak-memory regime (2025)
Journal Article
Brandner, K. (2025). Dynamics of microscale and nanoscale systems in the weak-memory regime. Physical Review Letters, 134(3), Article 037401. https://doi.org/10.1103/physrevlett.134.037101

Memory effects are ubiquitous in small-scale systems. They emerge from interactions between accessible and inaccessible degrees of freedom and give rise to evolution equations that are nonlocal in time. If the characteristic timescales of accessible... Read More about Dynamics of microscale and nanoscale systems in the weak-memory regime.

Stochastic Thermodynamics at the Quantum-Classical Boundary: A Self-Consistent Framework Based on Adiabatic-Response Theory (2024)
Journal Article
Eglinton, J., Carollo, F., Lesanovsky, I., & Brandner, K. (2024). Stochastic Thermodynamics at the Quantum-Classical Boundary: A Self-Consistent Framework Based on Adiabatic-Response Theory. Quantum, 8, Article 1486. https://doi.org/10.22331/q-2024-09-26-1486

Microscopic thermal machines promise to play an important role in future quantum technologies. Making such devices widely applicable will require effective strategies to channel their output into easily accessible storage systems like classical degre... Read More about Stochastic Thermodynamics at the Quantum-Classical Boundary: A Self-Consistent Framework Based on Adiabatic-Response Theory.

Rydberg-ion flywheel for quantum work storage (2023)
Journal Article
Martins, W. S., Carollo, F., Li, W., Brandner, K., & Lesanovsky, I. (2023). Rydberg-ion flywheel for quantum work storage. Physical Review A, 108(5), Article L050201. https://doi.org/10.1103/PhysRevA.108.L050201

Trapped ions provide a platform for quantum technologies that offers long coherence times and high degrees of scalability and controllability. Here, we use this platform to develop a realistic model of a thermal device consisting of two laser-driven,... Read More about Rydberg-ion flywheel for quantum work storage.

Thermodynamics of permutation-invariant quantum many-body systems: A group-theoretical framework (2023)
Journal Article
Yadin, B., Morris, B., & Brandner, K. (2023). Thermodynamics of permutation-invariant quantum many-body systems: A group-theoretical framework. Physical Review Research, 5(3), Article 033018. https://doi.org/10.1103/physrevresearch.5.033018

Quantum systems of indistinguishable particles are commonly described using the formalism of second quantization, which relies on the assumption that any admissible quantum state must be either symmetric or antisymmetric under particle permutations.... Read More about Thermodynamics of permutation-invariant quantum many-body systems: A group-theoretical framework.

Thermodynamic geometry of ideal quantum gases: a general framework and a geometric picture of BEC-enhanced heat engines (2023)
Journal Article
Eglinton, J., Pyhäranta, T., Saito, K., & Brandner, K. (2023). Thermodynamic geometry of ideal quantum gases: a general framework and a geometric picture of BEC-enhanced heat engines. New Journal of Physics, 25(4), Article 043014. https://doi.org/10.1088/1367-2630/acc966

Thermodynamic geometry provides a physically transparent framework to describe thermodynamic processes in meso- and micro-scale systems that are driven by slow variations of external control parameters. Focusing on periodic driving for thermal machin... Read More about Thermodynamic geometry of ideal quantum gases: a general framework and a geometric picture of BEC-enhanced heat engines.

Lee-Yang theory of Bose-Einstein condensation (2023)
Journal Article
Brange, F., Pyhäranta, T., Heinonen, E., Brandner, K., & Flindt, C. (2023). Lee-Yang theory of Bose-Einstein condensation. Physical Review A, 107(3), Article 033324. https://doi.org/10.1103/physreva.107.033324

Bose-Einstein condensation happens as a gas of bosons is cooled below its transition temperature, and the ground state becomes macroscopically occupied. The phase transition occurs in the thermodynamic limit of many particles. However, recent experim... Read More about Lee-Yang theory of Bose-Einstein condensation.

Many-Body Radiative Decay in Strongly Interacting Rydberg Ensembles (2022)
Journal Article
Nill, C., Brandner, K., Olmos, B., Carollo, F., & Lesanovsky, I. (2022). Many-Body Radiative Decay in Strongly Interacting Rydberg Ensembles. Physical Review Letters, 129(24), https://doi.org/10.1103/physrevlett.129.243202

When atoms are excited to high-lying Rydberg states they interact strongly with dipolar forces. The resulting state-dependent level shifts allow to study many-body systems displaying intriguing nonequilibrium phenomena, such as constrained spin syste... Read More about Many-Body Radiative Decay in Strongly Interacting Rydberg Ensembles.

Thermodynamic bounds on coherent transport in periodically driven conductors (2021)
Journal Article
Potanina, E., Flindt, C., Moskalets, M., & Brandner, K. (2021). Thermodynamic bounds on coherent transport in periodically driven conductors. Physical Review X, 11(2), 1-26. https://doi.org/10.1103/physrevx.11.021013

Periodically driven coherent conductors provide a universal platform for the development of quantum transport devices. Here, we lay down a comprehensive theory to describe the thermodynamics of these systems. We first focus on moderate thermoelectric... Read More about Thermodynamic bounds on coherent transport in periodically driven conductors.

Nonequilibrium Many-Body Quantum Engine Driven by Time-Translation Symmetry Breaking (2020)
Journal Article
Carollo, F., Brandner, K., & Lesanovsky, I. (2020). Nonequilibrium Many-Body Quantum Engine Driven by Time-Translation Symmetry Breaking. Physical Review Letters, 125(24), Article 240602. https://doi.org/10.1103/PhysRevLett.125.240602

Quantum many-body systems out of equilibrium can host intriguing phenomena such as transitions to exotic dynamical states. Although this emergent behaviour can be observed in experiments, its potential for technological applications is largely unexpl... Read More about Nonequilibrium Many-Body Quantum Engine Driven by Time-Translation Symmetry Breaking.

Nonequilibrium Quantum Many-Body Rydberg Atom Engine (2020)
Journal Article
Carollo, F., Gambetta, F. M., Brandner, K., Garrahan, J. P., & Lesanovsky, I. (2020). Nonequilibrium Quantum Many-Body Rydberg Atom Engine. Physical Review Letters, 124(17), Article 170602. https://doi.org/10.1103/physrevlett.124.170602

The standard approach to quantum engines is based on equilibrium systems and on thermo-dynamic transformations between Gibbs states. However, non-equilibrium quantum systems offer enhanced experimental flexibility in the control of their parameters a... Read More about Nonequilibrium Quantum Many-Body Rydberg Atom Engine.

Coherent Transport in Periodically Driven Mesoscopic Conductors: From Scattering Amplitudes to Quantum Thermodynamics (2020)
Journal Article
Brandner, K. (2020). Coherent Transport in Periodically Driven Mesoscopic Conductors: From Scattering Amplitudes to Quantum Thermodynamics. Zeitschrift fur Naturforschung A, 75(5), 483-500. https://doi.org/10.1515/zna-2020-0056

Unified Thermodynamic Uncertainty Relations in Linear Response (2018)
Journal Article
Macieszczak, K., Brandner, K., & Garrahan, J. P. (2018). Unified Thermodynamic Uncertainty Relations in Linear Response. Physical Review Letters, 121(13), Article 130601. https://doi.org/10.1103/physrevlett.121.130601

Thermodynamic uncertainty relations (TURs) are recently established relations between the relative uncertainty of time-integrated currents and entropy production in non-equilibrium systems. For small perturbations away from equilibrium, linear respon... Read More about Unified Thermodynamic Uncertainty Relations in Linear Response.

Thermodynamic Bounds on Precision in Ballistic Multiterminal Transport (2018)
Journal Article
Saito, K., Brandner, K., & Hanazato, T. (2018). Thermodynamic Bounds on Precision in Ballistic Multiterminal Transport. Physical Review Letters, 120(9), Article 090601. https://doi.org/10.1103/PhysRevLett.120.090601

© 2018 American Physical Society. For classical ballistic transport in a multiterminal geometry, we derive a universal trade-off relation between total dissipation and the precision, at which particles are extracted from individual reservoirs. Remark... Read More about Thermodynamic Bounds on Precision in Ballistic Multiterminal Transport.

Universal Coherence-Induced Power Losses of Quantum Heat Engines in Linear Response (2017)
Journal Article
Brandner, K., Bauer, M., & Seifert, U. (2017). Universal Coherence-Induced Power Losses of Quantum Heat Engines in Linear Response. Physical Review Letters, 119(17), Article 170602. https://doi.org/10.1103/PhysRevLett.119.170602

© 2017 American Physical Society. We identify a universal indicator for the impact of coherence on periodically driven quantum devices by dividing their power output into a classical contribution and one stemming solely from superpositions. Specializ... Read More about Universal Coherence-Induced Power Losses of Quantum Heat Engines in Linear Response.

Experimental Determination of Dynamical Lee-Yang Zeros (2017)
Journal Article
Brandner, K., Maisi, V. F., Pekola, J. P., Garrahan, J. P., & Flindt, C. (2017). Experimental Determination of Dynamical Lee-Yang Zeros. Physical Review Letters, 118(18), Article 180601. https://doi.org/10.1103/physrevlett.118.180601

Statistical physics provides the concepts and methods to explain the phase behavior of interacting many-body systems. Investigations of Lee-Yang zeros - complex singularities of the free energy in systems of finite size - have led to a unified unders... Read More about Experimental Determination of Dynamical Lee-Yang Zeros.

Thermodynamics of micro- and nano-systems driven by periodic temperature variations (2015)
Journal Article
Seifert, U., Brandner, K., & Saito, K. (2015). Thermodynamics of micro- and nano-systems driven by periodic temperature variations. Physical Review X, 5(3), Article 031019. https://doi.org/10.1103/PhysRevX.5.031019

We introduce a general framework for analyzing the thermodynamics of small systems that are driven by both a periodic temperature variation and some external parameter modulating their energy. This setup covers, in particular, periodic micro- and nan... Read More about Thermodynamics of micro- and nano-systems driven by periodic temperature variations.

Classical Nernst engine (2014)
Journal Article
Brandner, K., Saito, K., Stark, J., & Seifert, U. (2014). Classical Nernst engine. Physical Review Letters, 112(14), Article 140601. https://doi.org/10.1103/physrevlett.112.140601

We introduce a simple model for an engine based on the Nernst effect. In the presence of a magnetic field, a vertical heat current can drive a horizontal particle current against a chemical potential. For a microscopic model invoking classical partic... Read More about Classical Nernst engine.