The arrow of time, irreversibility, equilibrium and measurement in quantum mechanics

• URL: http://arxiv.org/abs/2607.19142v2
• Date: Thu, 23 Jul 2026 17:38:48 GMT
• Title: The arrow of time, irreversibility, equilibrium and measurement in quantum mechanics
• Abstract summary: We show that quantum systems with continuous spectra can be accommodated naturally and consistently.<n>The time-reversal symmetry associated with unitary time evolution of the quantum state gives rise to time-symmetry breaking.<n>The emergence of this non-unitary time-asymmetry leads to microcanonical equilibrium states in which all quantum coherence is lost.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Quantum mechanics is widely recognised as being incomplete. It is not consistent with the second law of thermodynamics and does not provide a scientifically credible physical account of the measurement process, the means by which coherence is broken and classically observable states are recorded. This has led to many ad hoc assumptions being used to account for various properties of quantum systems, among which is the coherence time of quantum devices that determines their ability to perform computations. Here, we show that all these properties can be accommodated naturally and consistently in the context of quantum systems which exhibit continuous spectra, as arises in the thermodynamic limit of large systems. In particular, for isolated systems we show that the time-reversal symmetry associated with unitary time evolution of the quantum state gives rise to time-symmetry breaking and a semi-group evolution which attains thermodynamic equilibrium at long times. Moreover, the emergence of this non-unitary time-asymmetry leads to microcanonical equilibrium states in which all quantum coherence is lost and is accompanied by the transformation of pure states into mixtures, leading in turn to an increase in entropy. Inclusion of a macroscopic measurement apparatus shows how the outcome of a measurement corresponds to the von Neumann projection postulate, arising with probabilities in conformance with the Born rule. The mathematical structure of the theory which applies to quantum systems with continuous spectra is closely analogous to the classical ergodic theory of dynamical systems and the conditions under which they attain equilibrium states.

Related papers

• The Quantum Mechanics of Rare Events: From Quantum Walks to Stochastic Inflation [1.145356152201166]
  We show that the dominant rare fluctuations minimize the measurement-induced relative entropy.<n>This perspective provides a thermodynamic description of a wide range of open quantum systems.<n>We show that the evolution of the density matrix of long wavelength fields on a fixed de Sitter background breaks the KMS symmetry.
  arXiv  Detail & Related papers  (2026-08-06T17:33:55Z)
• When Isolated Quantum Systems Appear Classical [35.18016233072556]
  We show that classical behavior may emerge even when substantial coherence remains present in the equilibrium state.<n>This establishes a direct connection between two foundational questions: the origin of thermalization in isolated quantum systems and the quantum-to-classical transition.
  arXiv  Detail & Related papers  (2026-06-17T15:30:00Z)
• Time Symmetry, Retrocausality, and Emergent Collapse: The Tlalpan Interpretation of Quantum Mechanics [51.56484100374058]
  The Tlalpan Interpretation (QTI) proposes that the wavefunction collapse is not a primitive, axiomatic rule but an emergent phenomenon.<n>The novelty of QTI lies in its embedding of collapse within the conceptual language of critical phenomena in statistical physics.
  arXiv  Detail & Related papers  (2025-08-25T20:30:56Z)
• Measurement-Induced Dynamical Quantum Thermalization [0.0]
  We study how the measurement of one or more observables subdivides the system into observed and non-observed Hilbert subspaces.<n>We find this to be more generally fulfilled than in the scenario of the eigenstate thermalization hypothesis (ETH)
  arXiv  Detail & Related papers  (2025-05-27T00:08:55Z)
• Spontaneous irreversibility and objective thermalization in stochastic modifications of quantum theory [0.0]
  We argue that quantum theory is an effective theory and requires corrections to accurately describe systems approaching the thermodynamic limit.<n>A fluctuation-dissipation relation guarantees physical consistency including norm preservation, energy conservation, no superluminal signalling and the emergence of microcanonical equilibrium.<n>The dynamics of the model describe spontaneous symmetry breaking, quantum state reduction and objective quantum thermalization for individual systems.
  arXiv  Detail & Related papers  (2025-04-22T18:38:28Z)
• Precision is not limited by the second law of thermodynamics [0.2094057281590807]
  Physical devices operating out of equilibrium are inherently affected by thermal fluctuations, limiting their operational precision. Our theoretical discovery presents an quantum many-body system that achieves clock precision scaling exponentially with entropy dissipation. This finding demonstrates that coherent quantum dynamics can surpass the traditional thermodynamic precision limits, potentially guiding the development of future high-precision, low-dissipation quantum devices.
  arXiv  Detail & Related papers  (2024-07-10T18:00:04Z)
• Quantum Instability [30.674987397533997]
  We show how a time-independent, finite-dimensional quantum system can give rise to a linear instability corresponding to that in the classical system. An unstable quantum system has a richer spectrum and a much longer recurrence time than a stable quantum system.
  arXiv  Detail & Related papers  (2022-08-05T19:53:46Z)
• Gauge Quantum Thermodynamics of Time-local non-Markovian Evolutions [77.34726150561087]
  We deal with a generic time-local non-Markovian master equation. We define current and power to be process-dependent as in classical thermodynamics. Applying the theory to quantum thermal engines, we show that gauge transformations can change the machine efficiency.
  arXiv  Detail & Related papers  (2022-04-06T17:59:15Z)
• Equilibration of Non-Markovian Quantum Processes in Finite Time Intervals [0.0]
  Quantum processes are shown, within finite time intervals and for finite dimensional time Hamiltonians, to be close to a corresponding stationary equilibrium process. This dictates conditions on time scales at when the multitime statistics of any arbitrary non-equilibrium quantum process look equilibrium on average.
  arXiv  Detail & Related papers  (2021-12-02T10:18:36Z)
• Sensing quantum chaos through the non-unitary geometric phase [62.997667081978825]
  We propose a decoherent mechanism for sensing quantum chaos. The chaotic nature of a many-body quantum system is sensed by studying the implications that the system produces in the long-time dynamics of a probe coupled to it.
  arXiv  Detail & Related papers  (2021-04-13T17:24:08Z)
• Entropic Uncertainty Relations and the Quantum-to-Classical transition [77.34726150561087]
  We aim to shed some light on the quantum-to-classical transition as seen through the analysis of uncertainty relations. We employ entropic uncertainty relations to show that it is only by the inclusion of imprecision in our model of macroscopic measurements that we can prepare a system with two simultaneously well-defined quantities.
  arXiv  Detail & Related papers  (2020-03-04T14:01:17Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.