A Note on the Relativistic Transformation Properties of Quantum Stochastic Calculus

We present a simple argument to derive the transformation of the quantum stochastic calculus formalism between inertial observers and derive the quantum open system dynamics for a system moving in a vacuum (or, more generally, a coherent) quantum field under the usual Markov approximation. We argue,...

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Main Author: John E. Gough
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Entropy
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Online Access:https://www.mdpi.com/1099-4300/27/5/529
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author John E. Gough
author_facet John E. Gough
author_sort John E. Gough
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description We present a simple argument to derive the transformation of the quantum stochastic calculus formalism between inertial observers and derive the quantum open system dynamics for a system moving in a vacuum (or, more generally, a coherent) quantum field under the usual Markov approximation. We argue, however, that, for uniformly accelerated open systems, the formalism must break down as we move from a Fock representation over the algebra of field observables over all of Minkowski space to the restriction regarding the algebra of observables over a Rindler wedge. This leads to quantum noise having a unitarily inequivalent non-Fock representation: in particular, the latter is a thermal representation at the Unruh temperature. The unitary inequivalence is ultimately a consequence of the underlying flat noise spectrum approximation for the fundamental quantum stochastic processes. We derive the quantum stochastic limit for a uniformly accelerated (two-level) detector and establish an open system description of the relaxation to thermal equilibrium at the Unruh temperature.
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spelling doaj-art-1f7ec44dbbc5418a9a3b8e5412bc6c962025-08-20T03:47:49ZengMDPI AGEntropy1099-43002025-05-0127552910.3390/e27050529A Note on the Relativistic Transformation Properties of Quantum Stochastic CalculusJohn E. Gough0Department of Physics, Aberystwyth University, Aberystwyth SY23 3QR, UKWe present a simple argument to derive the transformation of the quantum stochastic calculus formalism between inertial observers and derive the quantum open system dynamics for a system moving in a vacuum (or, more generally, a coherent) quantum field under the usual Markov approximation. We argue, however, that, for uniformly accelerated open systems, the formalism must break down as we move from a Fock representation over the algebra of field observables over all of Minkowski space to the restriction regarding the algebra of observables over a Rindler wedge. This leads to quantum noise having a unitarily inequivalent non-Fock representation: in particular, the latter is a thermal representation at the Unruh temperature. The unitary inequivalence is ultimately a consequence of the underlying flat noise spectrum approximation for the fundamental quantum stochastic processes. We derive the quantum stochastic limit for a uniformly accelerated (two-level) detector and establish an open system description of the relaxation to thermal equilibrium at the Unruh temperature.https://www.mdpi.com/1099-4300/27/5/529quantum Itō calculusrelativistic fieldsDavies–Unruh effect
spellingShingle John E. Gough
A Note on the Relativistic Transformation Properties of Quantum Stochastic Calculus
Entropy
quantum Itō calculus
relativistic fields
Davies–Unruh effect
title A Note on the Relativistic Transformation Properties of Quantum Stochastic Calculus
title_full A Note on the Relativistic Transformation Properties of Quantum Stochastic Calculus
title_fullStr A Note on the Relativistic Transformation Properties of Quantum Stochastic Calculus
title_full_unstemmed A Note on the Relativistic Transformation Properties of Quantum Stochastic Calculus
title_short A Note on the Relativistic Transformation Properties of Quantum Stochastic Calculus
title_sort note on the relativistic transformation properties of quantum stochastic calculus
topic quantum Itō calculus
relativistic fields
Davies–Unruh effect
url https://www.mdpi.com/1099-4300/27/5/529
work_keys_str_mv AT johnegough anoteontherelativistictransformationpropertiesofquantumstochasticcalculus
AT johnegough noteontherelativistictransformationpropertiesofquantumstochasticcalculus