The Experts below are selected from a list of 11301 Experts worldwide ranked by ideXlab platform
Jonathan Oppenheim - One of the best experts on this subject based on the ideXlab platform.
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limitations on the evolution of quantum coherences towards fully quantum second Laws of Thermodynamics
Physical Review Letters, 2015Co-Authors: Piotr Cwiklinski, Michal Horodecki, Michal Studzinski, Jonathan OppenheimAbstract:: The second law of Thermodynamics places a limitation into which states a system can evolve into. For systems in contact with a heat bath, it can be combined with the law of energy conservation, and it says that a system can only evolve into another if the free energy goes down. Recently, it's been shown that there are actually many second Laws, and that it is only for large macroscopic systems that they all become equivalent to the ordinary one. These additional second Laws also hold for quantum systems, and are, in fact, often more relevant in this regime. They place a restriction on how the probabilities of energy levels can evolve. Here, we consider additional restrictions on how the coherences between energy levels can evolve. Coherences can only go down, and we provide a set of restrictions which limit the extent to which they can be maintained. We find that coherences over energy levels must decay at rates that are suitably adapted to the transition rates between energy levels. We show that the limitations are matched in the case of a single qubit, in which case we obtain the full characterization of state-to-state transformations. For higher dimensions, we conjecture that more severe constraints exist. We also introduce a new class of thermodynamical operations which allow for greater manipulation of coherences and study its power with respect to a class of operations known as thermal operations.
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the second Laws of quantum Thermodynamics
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Fernando G S L Brandao, Jonathan Oppenheim, Michal Horodecki, Nelly Huei Ying Ng, Stephanie WehnerAbstract:The second law of Thermodynamics places constraints on state transformations. It applies to systems composed of many particles, however, we are seeing that one can formulate Laws of Thermodynamics when only a small number of particles are interacting with a heat bath. Is there a second law of Thermodynamics in this regime? Here, we find that for processes which are approximately cyclic, the second law for microscopic systems takes on a different form compared to the macroscopic scale, imposing not just one constraint on state transformations, but an entire family of constraints. We find a family of free energies which generalize the traditional one, and show that they can never increase. The ordinary second law relates to one of these, with the remainder imposing additional constraints on thermodynamic transitions. We find three regimes which determine which family of second Laws govern state transitions, depending on how cyclic the process is. In one regime one can cause an apparent violation of the usual second law, through a process of embezzling work from a large system which remains arbitrarily close to its original state. These second Laws are relevant for small systems, and also apply to individual macroscopic systems interacting via long-range interactions. By making precise the definition of thermal operations, the Laws of Thermodynamics are unified in this framework, with the first law defining the class of operations, the zeroth law emerging as an equivalence relation between thermal states, and the remaining Laws being monotonicity of our generalized free energies.
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fundamental limitations for quantum and nanoscale Thermodynamics
Nature Communications, 2013Co-Authors: Michal Horodecki, Jonathan OppenheimAbstract:The usual Laws of Thermodynamics that are valid for macroscopic systems do not necessarily apply to the nanoscale, where quantum effects become important. Here, the authors develop a theoretical framework based on quantum information theory to properly treat Thermodynamics at the nanoscale.
Marlan O Scully - One of the best experts on this subject based on the ideXlab platform.
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quantum photocell using quantum coherence to reduce radiative recombination and increase efficiency
Physical Review Letters, 2010Co-Authors: Marlan O ScullyAbstract:The fundamental limit to photovoltaic efficiency is widely thought to be radiative recombination which balances radiative absorption. We here show that it is possible to break detailed balance via quantum coherence, as in the case of lasing without inversion and the photo-Carnot quantum heat engine. This yields, in principle, a quantum limit to photovoltaic operation which can exceed the classical one. The present work is in complete accord with the Laws of Thermodynamics.
J E Hirsch - One of the best experts on this subject based on the ideXlab platform.
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Inconsistency of the conventional theory of superconductivity
EPL (Europhysics Letters), 2020Co-Authors: J E HirschAbstract:In a process where the temperature of a type I superconductor in a magnetic field changes, the conventional theory of superconductivity predicts that Joule heat is generated and that the final state is independent of the speed of the process. I show that these two predictions cannot be simultaneously reconciled with the Laws of Thermodynamics. I propose a resolution of this paradox.
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entropy generation and momentum transfer in the superconductor normal and normal superconductor phase transformations and the consistency of the conventional theory of superconductivity
arXiv: Superconductivity, 2017Co-Authors: J E HirschAbstract:Since the discovery of the Meissner effect the superconductor to normal (S-N) phase transition in the presence of a magnetic field is understood to be a first order phase transformation that is reversible under ideal conditions and obeys the Laws of Thermodynamics. The reverse (N-S) transition is the Meissner effect. This implies in particular that the kinetic energy of the supercurrent is not dissipated as Joule heat in the process where the superconductor becomes normal and the supercurrent stops. In this paper we analyze the entropy generation and the momentum transfer between the supercurrent and the body in the S-N transition and the N-S transition as described by the conventional theory of superconductivity. We find that it is impossible to explain the transition in a way that is consistent with the Laws of Thermodynamics unless the momentum transfer between the supercurrent and the body occurs with zero entropy generation, for which the conventional theory of superconductivity provides no mechanism. Instead, we point out that the alternative theory of hole superconductivity does not encounter such difficulties.
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entropy generation and momentum transfer in the superconductor to normal phase transformation and the consistency of the conventional theory of superconductivity
2017Co-Authors: J E HirschAbstract:Since the discovery of the Meissner effect the superconductor to normal (S-N) phase transition in the presence of a magnetic field is understood to be a first order phase transformation that is reversible under ideal conditions and obeys the Laws of Thermodynamics. The reverse (N-S) transition is the Meissner effect. This implies in particular that the kinetic energy of the supercurrent is not dissipated as Joule heat in the process where the superconductor becomes normal and the supercurrent stops. In this paper we analyze the entropy generation and the momentum transfer between the supercurrent and the body in the S-N transition and the N-S transition as described by the conventional theory of superconductivity. We find that it is impossible to explain the transition in a way that is consistent with the Laws of Thermodynamics unless the momentum transfer between the supercurrent and the body occurs with zero entropy generation, for which the conventional theory of superconductivity provides no mechanism. Instead, we point out that the alternative theory of hole superconductivity does not encounter such difficulties.
Michal Horodecki - One of the best experts on this subject based on the ideXlab platform.
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limitations on the evolution of quantum coherences towards fully quantum second Laws of Thermodynamics
Physical Review Letters, 2015Co-Authors: Piotr Cwiklinski, Michal Horodecki, Michal Studzinski, Jonathan OppenheimAbstract:: The second law of Thermodynamics places a limitation into which states a system can evolve into. For systems in contact with a heat bath, it can be combined with the law of energy conservation, and it says that a system can only evolve into another if the free energy goes down. Recently, it's been shown that there are actually many second Laws, and that it is only for large macroscopic systems that they all become equivalent to the ordinary one. These additional second Laws also hold for quantum systems, and are, in fact, often more relevant in this regime. They place a restriction on how the probabilities of energy levels can evolve. Here, we consider additional restrictions on how the coherences between energy levels can evolve. Coherences can only go down, and we provide a set of restrictions which limit the extent to which they can be maintained. We find that coherences over energy levels must decay at rates that are suitably adapted to the transition rates between energy levels. We show that the limitations are matched in the case of a single qubit, in which case we obtain the full characterization of state-to-state transformations. For higher dimensions, we conjecture that more severe constraints exist. We also introduce a new class of thermodynamical operations which allow for greater manipulation of coherences and study its power with respect to a class of operations known as thermal operations.
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the second Laws of quantum Thermodynamics
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Fernando G S L Brandao, Jonathan Oppenheim, Michal Horodecki, Nelly Huei Ying Ng, Stephanie WehnerAbstract:The second law of Thermodynamics places constraints on state transformations. It applies to systems composed of many particles, however, we are seeing that one can formulate Laws of Thermodynamics when only a small number of particles are interacting with a heat bath. Is there a second law of Thermodynamics in this regime? Here, we find that for processes which are approximately cyclic, the second law for microscopic systems takes on a different form compared to the macroscopic scale, imposing not just one constraint on state transformations, but an entire family of constraints. We find a family of free energies which generalize the traditional one, and show that they can never increase. The ordinary second law relates to one of these, with the remainder imposing additional constraints on thermodynamic transitions. We find three regimes which determine which family of second Laws govern state transitions, depending on how cyclic the process is. In one regime one can cause an apparent violation of the usual second law, through a process of embezzling work from a large system which remains arbitrarily close to its original state. These second Laws are relevant for small systems, and also apply to individual macroscopic systems interacting via long-range interactions. By making precise the definition of thermal operations, the Laws of Thermodynamics are unified in this framework, with the first law defining the class of operations, the zeroth law emerging as an equivalence relation between thermal states, and the remaining Laws being monotonicity of our generalized free energies.
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fundamental limitations for quantum and nanoscale Thermodynamics
Nature Communications, 2013Co-Authors: Michal Horodecki, Jonathan OppenheimAbstract:The usual Laws of Thermodynamics that are valid for macroscopic systems do not necessarily apply to the nanoscale, where quantum effects become important. Here, the authors develop a theoretical framework based on quantum information theory to properly treat Thermodynamics at the nanoscale.
Terry Rudolph - One of the best experts on this subject based on the ideXlab platform.
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quantum coherence time translation symmetry and Thermodynamics
Physical Review X, 2015Co-Authors: Matteo Lostaglio, Kamil Korzekwa, David Jennings, Terry RudolphAbstract:Quantum mechanics and Thermodynamics are fundamental fields of physics. Scientists show how the processing of quantum coherence is constrained by the Laws of Thermodynamics.