pith. machine review for the scientific record. sign in

arxiv: 2605.07090 · v1 · submitted 2026-05-08 · 🪐 quant-ph · physics.hist-ph

Recognition: 2 theorem links

· Lean Theorem

Decoherence without the state: A causal quantum Darwinist approach

Authors on Pith no claims yet

Pith reviewed 2026-05-11 01:13 UTC · model grok-4.3

classification 🪐 quant-ph physics.hist-ph
keywords decoherenceconsistent historiesquantum Darwinismunitary evolutioncausal influencesemergence of statespointer basistime asymmetry
0
0 comments X

The pith

Decoherence defined solely by causal influences in unitary dynamics, together with its dual, selects a privileged consistent history set from which states and outcomes emerge.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper seeks to unify environmentally induced decoherence with the consistent histories approach by redefining decoherence without assuming a quantum state exists beforehand. It treats decoherence as arising from the causal structure of unitary dynamics that allows information about certain observables to spread. The time-reversed version of this process causes the state to appear, and together they pick out one special set of consistent histories for any given unitary circuit. Examples illustrate how outcomes come from decoherence and states from the dual process. If correct, this shows that the emergence of states from decoherence is what was missing to connect these two descriptions of the classical world.

Core claim

Decoherence is characterized purely as a feature of the unitary dynamics: the causal influences needed for information about observables to proliferate to other systems. Its dual, defined by reversing time in the dynamics, causes the quantum state to emerge. For arbitrary unitary circuits on multiple systems, these two processes together identify a unique consistent history set. In this set, decoherence produces the outcomes while dual decoherence produces the states. This dynamics-first perspective accounts for the suppression of off-diagonal elements in the density matrix, the direction of time in decoherence, and the stability of the pointer basis.

What carries the argument

Causal decoherence, defined via the unitary dynamics' information-proliferating causal influences on observables, along with its time-reversed dual that generates the state.

If this is right

  • Any unitary circuit has a dynamically selected consistent history set without extra postulates.
  • The quantum state is not fundamental but emerges from the dual decoherence process.
  • Outcomes of measurements arise as a direct result of the decoherence mechanism.
  • The pointer basis gains robustness from the causal proliferation of information.
  • Time asymmetry appears naturally from distinguishing decoherence from its dual.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • This view supports a causal interpretation of quantum mechanics where dynamics alone determine the classical realm.
  • It could lead to new ways to compute consistent histories in complex circuits by tracing causal influences.
  • The framework might extend to explain why certain observables become classical in open quantum systems without invoking environments explicitly.
  • Testable predictions could arise in quantum information experiments tracking information flow in small circuits.

Load-bearing premise

That a definition of decoherence based only on causal influences required for information proliferation in the unitary dynamics is sufficient, without presupposing a quantum state or any additional selection rules.

What would settle it

Identification of a unitary circuit where decoherence and dual decoherence do not yield a single privileged consistent history set, or where the emerging state from dual decoherence contradicts standard quantum mechanical predictions for that circuit.

Figures

Figures reproduced from arXiv: 2605.07090 by Jaros{\l}aw K. Korbicz, Nick Ormrod, Tein van der Lugt, Y\`il\`e Y\=ing.

Figure 1
Figure 1. Figure 1: illustrates the competition to achieve decoherence through some simple examples. In Example 3.6, all observables survive, and thus no nontrivial observables reproduce. Hence no nontrivial observables succeed in doing both; the decoherent algebra is trivial. In Example 3.7, all observables reproduce, and thus no nontrivial observables survive. Again, the decoherent algebra is trivial. But in Example 3.8, a … view at source ↗
Figure 2
Figure 2. Figure 2: Model of a single measurement. Systems of interest are labelled in black. Decohered and dual decohered algebras, associated emergent events, and their interpretations are labelled in blue. Each decohered algebra is depicted above the corresponding dual decohered algebra because the former arises from the interaction between the system and its future while the latter arises from its interaction with its pas… view at source ↗
Figure 3
Figure 3. Figure 3: Model of two incompatible measurements decorated as before with decohered and dual decohered algebras, associated events, and their interpretation. OT denotes the operator that is transformed to the Z-operator of the (unlabelled) output system of W = W(·)W † . We assume that [OT , ZT ] ̸= 0. event at S corresponding to the outcome of the first measurement thus fails to emerge not only with respect to B, bu… view at source ↗
Figure 4
Figure 4. Figure 4: Model of the Wigner’s friend scenario decorated as before with decohered and dual decohered algebras, associated events, and their interpretation. 33 [PITH_FULL_IMAGE:figures/full_fig_p033_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: In [24], the first step to obtaining the preferred decompositions is to break the wires corresponding to all systems of interest, thus obtaining a unitary channel V : AoutBoutC outP → AinBinC inF , where P (for “past”) is the bottom-right input to the circuit and F (for “future”) is the top-right output. The labels P and F are omitted from the diagram because they are not being considered as systems of int… view at source ↗
read the original abstract

The consistent histories formalism can be used to describe histories comprised of events across many systems, times, and places, plausibly rich enough to describe our experiences of the classical world; however, many consistent history sets are nonclassical and thus not obviously relevant to our experiences. Meanwhile, the program of environmentally induced decoherence identifies dynamically privileged classical degrees of freedom, but provides no general account of when or how many such degrees of freedom consistently combine to form histories. This work shows that the strengths of these two approaches can be combined by adopting a dynamics-first perspective on decoherence. Inspired by quantum causal models and quantum Darwinism, we define the process of decoherence in terms of the causal influences through unitary dynamics required for the proliferation of information about observables. We characterise decoherence as a property of the unitary dynamics, without presupposing the existence of any quantum state. Instead, we show that the state emerges from dual decoherence, related to decoherence by time-reversal of the unitary dynamics. Indeed, for any set of systems in an arbitrary unitary circuit, decoherence and its dual single out a privileged consistent history set -- and we demonstrate through examples that states emerge from dual decoherence while outcomes emerge from decoherence. Hence the idea that quantum states emerge from the process of decoherence turns out to be the key missing ingredient for unifying environmentally induced decoherence and consistent histories. Taking this idea ontologically seriously leads to a recently proposed causal interpretation of quantum theory or a dynamics-first version of the Everett interpretation. The causal approach also sheds light on the suppression of off-diagonal terms, time asymmetry, and robustness of the pointer basis.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The manuscript proposes a dynamics-first definition of decoherence based on causal influences in unitary circuits enabling information proliferation about observables, without presupposing quantum states. It introduces dual decoherence via time-reversal of the dynamics, claiming that decoherence and its dual together select a privileged consistent history set for arbitrary unitary circuits. States are said to emerge from dual decoherence, while outcomes emerge from decoherence, as demonstrated in examples. This approach aims to unify environmentally induced decoherence with the consistent histories formalism and leads to a causal interpretation of quantum theory.

Significance. If the central construction holds without implicit selection rules, the work would be significant for providing a state-independent mechanism to select privileged classical histories from unitary dynamics, addressing a key gap between decoherence and consistent histories. It merits credit for grounding the emergence of both states and outcomes in causal processes and for offering perspectives on time asymmetry and pointer-basis robustness. The approach builds on quantum causal models and Darwinism ideas in a coherent way.

major comments (3)
  1. [Abstract and § on decoherence definition] Abstract and definition of decoherence: the claim that decoherence is defined solely via causal influences in the unitary dynamics (without presupposing states or additional selection rules) requires an explicit, basis-independent construction of 'information proliferation about observables' and 'causal influences'; without it, the selection of the privileged consistent history set may not be unique or may tacitly reintroduce the consistency conditions the framework aims to avoid.
  2. [Examples section] Examples demonstrating emergence: the demonstrations that states emerge from dual decoherence and outcomes from decoherence must include full derivations showing that identification of proliferating observables does not rely on any pre-chosen partitioning or state; otherwise the central claim that decoherence and dual select the history set for arbitrary circuits is not fully supported.
  3. [Unification and consistent histories discussion] Unification claim: the paper should explicitly compare the selected history set to standard consistent-histories consistency conditions (e.g., via the decoherence functional) to confirm it is not circular with prior literature on which the causal framework builds.
minor comments (2)
  1. [Notation and figures] Notation for dual decoherence and causal influences could be clarified with additional diagrams or explicit equations relating the time-reversed unitary to the emergence of states.
  2. [Introduction] A few sentences in the introduction repeat material from the abstract; tightening would improve readability.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their thorough review and constructive feedback on our manuscript. We address each of the major comments in detail below, providing clarifications and indicating the revisions we will make to improve the manuscript.

read point-by-point responses
  1. Referee: Abstract and § on decoherence definition: the claim that decoherence is defined solely via causal influences in the unitary dynamics (without presupposing states or additional selection rules) requires an explicit, basis-independent construction of 'information proliferation about observables' and 'causal influences'; without it, the selection of the privileged consistent history set may not be unique or may tacitly reintroduce the consistency conditions the framework aims to avoid.

    Authors: We appreciate this point, as it touches on the core of our dynamics-first approach. The manuscript defines information proliferation via the causal influences in the unitary circuit, specifically through the ability of an observable to become correlated with multiple independent systems via the evolution, as formalized in the quantum causal model framework. This construction is basis-independent because it derives from the unitary operator's action on the circuit's causal graph, without reference to any Hilbert space basis or initial state. Regarding uniqueness, the set of such observables is determined uniquely by the circuit's structure for a given dynamics. We do not reintroduce consistency conditions; rather, the selected histories are shown to be consistent as a consequence. To strengthen this, we will include a more formal, explicit definition and a proof of uniqueness in the revised section on the decoherence definition. revision: partial

  2. Referee: Examples section: the demonstrations that states emerge from dual decoherence and outcomes from decoherence must include full derivations showing that identification of proliferating observables does not rely on any pre-chosen partitioning or state; otherwise the central claim that decoherence and dual select the history set for arbitrary circuits is not fully supported.

    Authors: We agree that the examples section would be strengthened by more detailed derivations. Currently, the examples demonstrate the emergence conceptually, but we acknowledge the need for explicit calculations. In the revised manuscript, we will provide full derivations for the key examples, explicitly tracing how the proliferating observables are identified solely from the causal structure of the unitary dynamics, without any pre-chosen partitioning or assumption of a quantum state. This will better support the generality of our claim for arbitrary circuits. revision: yes

  3. Referee: Unification claim: the paper should explicitly compare the selected history set to standard consistent-histories consistency conditions (e.g., via the decoherence functional) to confirm it is not circular with prior literature on which the causal framework builds.

    Authors: This suggestion is helpful for clarifying the relationship to existing literature. Our approach is not circular; the causal selection mechanism operates independently and yields histories that satisfy the consistency conditions. To make this explicit, we will add a comparison in the discussion section, including an analysis of the decoherence functional for the selected history sets in our examples. This will show how the vanishing of interference terms arises from the causal proliferation process, providing a dynamical basis for consistency without presupposing it. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected; derivation remains self-contained

full rationale

The paper defines decoherence as a property of unitary dynamics via causal influences enabling information proliferation about observables, explicitly without presupposing any quantum state, and derives the emergence of states from the time-reversed dual process. This is used to select a privileged consistent-history set for arbitrary circuits. No equations or definitions in the abstract or described framework reduce the output (privileged histories, emergent states/outcomes) to the inputs by construction, nor do they rename known results or smuggle ansatzes via self-citation. References to prior causal interpretations and consistent-histories literature provide context but do not bear the load of the central unification claim, which is demonstrated through examples as having independent content. The approach is presented as dynamics-first and falsifiable in principle against standard decoherence and histories formalisms.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 1 invented entities

The central claim rests on the assumption that unitary dynamics alone can be used to define causal influences and information proliferation without states, plus the existence of a time-reversal operation that yields dual decoherence.

axioms (2)
  • standard math The evolution is given by unitary dynamics on a circuit of systems.
    Invoked throughout the abstract as the sole dynamical input.
  • domain assumption Causal influences can be identified from the unitary circuit structure without reference to a state.
    Core to the new definition of decoherence.
invented entities (1)
  • dual decoherence no independent evidence
    purpose: Time-reversed counterpart that allows states to emerge
    Introduced to complement forward decoherence and select histories

pith-pipeline@v0.9.0 · 5614 in / 1369 out tokens · 33843 ms · 2026-05-11T01:13:27.238458+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

What do these tags mean?
matches
The paper's claim is directly supported by a theorem in the formal canon.
supports
The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses
The paper appears to rely on the theorem as machinery.
contradicts
The paper's claim conflicts with a theorem or certificate in the canon.
unclear
Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

56 extracted references · 56 canonical work pages

  1. [1]

    On the interpretation of measurement in quantum theory

    H Dieter Zeh. “On the interpretation of measurement in quantum theory”.Foundations of Physics1.1 (1970), pp. 69–76

  2. [2]

    Toward a quantum theory of observation

    H Dieter Zeh. “Toward a quantum theory of observation”.Foundations of Physics3.1 (1973), pp. 109–116

  3. [3]

    Pointer basis of quantum apparatus: Into what mixture does the wave packet collapse?

    Wojciech H Zurek. “Pointer basis of quantum apparatus: Into what mixture does the wave packet collapse?”Physical review D24.6 (1981), p. 1516

  4. [4]

    Environment-induced superselection rules

    Wojciech H Zurek. “Environment-induced superselection rules”.Physical review D26.8 (1982), p. 1862

  5. [5]

    Preferred States, Predictability, Classicality and the Environment- Induced Decoherence

    Wojciech H. Zurek. “Preferred States, Predictability, Classicality and the Environment- Induced Decoherence”. In:Physical Origins of Time Asymmetry. Ed. by J. J. Halliwell, J. Pérez-Mercader, and W. H. Zurek. Cambridge University Press, 1994, pp. 175–221

  6. [6]

    Consistent histories and the interpretation of quantum mechanics

    Robert B Griffiths. “Consistent histories and the interpretation of quantum mechanics”. Journal of Statistical Physics36 (1984), pp. 219–272

  7. [7]

    Cambridge University Press, 2003

    Robert B Griffiths.Consistent Quantum Theory. Cambridge University Press, 2003

  8. [8]

    Complexity, entropy and the physics of informa- tion

    Murray Gell-Mann and James Hartle. “Complexity, entropy and the physics of informa- tion”.SFI Studies in the Sciences of Complexity8 (1990), p. 425

  9. [9]

    On the consistent histories approach to quantum me- chanics

    Fay Dowker and Adrian Kent. “On the consistent histories approach to quantum me- chanics”.Journal of Statistical Physics82 (1996), pp. 1575–1646

  10. [10]

    Decoherence, einselection, and the quantum origins of the classical

    Wojciech H Zurek. “Decoherence, einselection, and the quantum origins of the classical”. Reviews of Modern Physics75.3 (2003), p. 715

  11. [11]

    Objective Properties from Sub- jective Quantum States: Environment as a Witness

    Harold Ollivier, David Poulin, and Wojciech H. Zurek. “Objective Properties from Sub- jective Quantum States: Environment as a Witness”.Physical Review Letters93.22 (2004)

  12. [12]

    Quantum Darwinism and envariance

    Wojciech H Zurek. “Quantum Darwinism and envariance”.Science and ultimate reality: Quantum theory, Cosmology, and Complexity(2004), pp. 121–137

  13. [13]

    Environment as a witness: Se- lective proliferation of information and emergence of objectivity in a quantum universe

    Harold Ollivier, David Poulin, and Wojciech H. Zurek. “Environment as a witness: Se- lective proliferation of information and emergence of objectivity in a quantum universe”. Physical Review A72.4 (2005)

  14. [14]

    Quantum Darwinism

    Wojciech H Zurek. “Quantum Darwinism”.Nature Physics5.3 (2009), pp. 181–188

  15. [15]

    Cambridge University Press, 2025

    Wojciech Hubert Zurek.Decoherence and Quantum Darwinism: From Quantum Foun- dations to Classical Reality. Cambridge University Press, 2025

  16. [16]

    Objectivity in a noisy photonicenvironmentthroughquantumstateinformationbroadcasting

    Jarosław Korbicz, Paweł Horodecki, and Ryszard Horodecki. “Objectivity in a noisy photonicenvironmentthroughquantumstateinformationbroadcasting”.Physical Review Letters112.12 (2014), p. 120402

  17. [17]

    Quantum origins of objectivity

    Ryszard Horodecki, Jarosław K Korbicz, and Paweł Horodecki. “Quantum origins of objectivity”.Physical Review A91.3 (2015), p. 032122

  18. [18]

    Roads to objectivity: Quantum Darwinism, Spectrum Broadcast Structures, and Strong quantum Darwinism – a review

    Jarosław K. Korbicz. “Roads to objectivity: Quantum Darwinism, Spectrum Broadcast Structures, and Strong quantum Darwinism – a review”.Quantum5 (2021), p. 571

  19. [19]

    QuantumCommonCausesandQuantumCausalModels

    John-MarkAllen,JonathanBarrett,DominicHorsman,CiaránLee,andRobertSpekkens. “QuantumCommonCausesandQuantumCausalModels”.Physical Review X7.3(2017). 42

  20. [20]

    Quantum Causal Models

    Jonathan Barrett, Robin Lorenz, and Ognyan Oreshkov. “Quantum Causal Models” (2020). arXiv: 1906.10726

  21. [21]

    Cyclicquantumcausalmodels

    JonathanBarrett,RobinLorenz,andOgnyanOreshkov.“Cyclicquantumcausalmodels”. Nature Communications12.1 (2021), pp. 1–15

  22. [22]

    Causal structure in the presence of sectorial constraints, with application to the quantum switch

    Nick Ormrod, Augustin Vanrietvelde, and Jonathan Barrett. “Causal structure in the presence of sectorial constraints, with application to the quantum switch”.Quantum7 (2023), p. 1028

  23. [23]

    Acausalderivationofthealgebraicapproachtoquantumsystems

    NickOrmrod.“Acausalderivationofthealgebraicapproachtoquantumsystems” (2025). arXiv: 2508.01111

  24. [24]

    Quantum influences and event relativity

    Nick Ormrod and Jonathan Barrett. “Quantum influences and event relativity” (2024). arXiv: 2401.18005

  25. [25]

    Springer Science & Business Media, 2000

    Douglas R Farenick.Algebras of Linear Transformations. Springer Science & Business Media, 2000

  26. [26]

    Theory of quantum error-correcting codes

    Emanuel Knill and Raymond Laflamme. “Theory of quantum error-correcting codes”. Physical Review A55.2 (1997), p. 900

  27. [27]

    Decoherence-free subspaces and subsystems

    Daniel A Lidar and K Birgitta Whaley. “Decoherence-free subspaces and subsystems”. In:Irreversible Quantum Dynamics. Springer, 2003, pp. 83–120

  28. [28]

    Review of Decoherence-Free Subspaces, Noiseless Subsystems, and Dy- namical Decoupling

    Daniel A Lidar. “Review of Decoherence-Free Subspaces, Noiseless Subsystems, and Dy- namical Decoupling”.Quantum Information and Computation for Chemistry(2014), pp. 295–354

  29. [29]

    Quantum darwinism

    Wojciech H Zurek. “Quantum darwinism”.Nature physics5.3 (2009), pp. 181–188

  30. [30]

    Strong quantum darwinism and strong inde- pendence are equivalent to spectrum broadcast structure

    Thao P Le and Alexandra Olaya-Castro. “Strong quantum darwinism and strong inde- pendence are equivalent to spectrum broadcast structure”.Physical Review Letters122.1 (2019), p. 010403

  31. [31]

    The meaning of redundancy and consensus in quantum objectivity

    Diana A Chisholm, Luca Innocenti, and G Massimo Palma. “The meaning of redundancy and consensus in quantum objectivity”.Quantum7 (2023), p. 1074

  32. [32]

    Remarks on the mind-body question

    Eugene P Wigner. “Remarks on the mind-body question”. In:Philosophical reflections and syntheses. Springer, 1995, pp. 247–260

  33. [33]

    Oxford University Press, USA, 2012

    David Wallace.The emergent multiverse: Quantum theory according to the Everett in- terpretation. Oxford University Press, USA, 2012

  34. [34]

    Quantum theory of probability and decisions

    David Deutsch. “Quantum theory of probability and decisions”.Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences455.1988 (1999), pp. 3129–3137

  35. [35]

    Everettandevidence

    HilaryGreavesandWayneMyrvold.“Everettandevidence”.Many worlds(2010),pp.264– 304

  36. [36]

    Probability in the Everett picture

    David Albert. “Probability in the Everett picture”.Many Worlds(2010), pp. 355–368

  37. [37]

    The problem of confirmation in the Everett interpretation

    Emily Adlam. “The problem of confirmation in the Everett interpretation”.Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics47 (2014), pp. 21–32

  38. [38]

    Information flow in entangled quantum systems

    David Deutsch and Patrick Hayden. “Information flow in entangled quantum systems”. Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engi- neering Sciences456.1999 (2000), pp. 1759–1774

  39. [39]

    Everettian relative states in the Heisenberg pic- ture

    Samuel Kuypers and David Deutsch. “Everettian relative states in the Heisenberg pic- ture”.Proceedings of the Royal Society A477.2246 (2021), p. 20200783

  40. [40]

    Solving the Measurement Problem: De Broglie– Bohm Loses Out to Everett

    Harvey R Brown and David Wallace. “Solving the Measurement Problem: De Broglie– Bohm Loses Out to Everett”.Foundations of Physics35 (2005), pp. 517–540

  41. [41]

    Comment on Lockwood

    David Deutsch. “Comment on Lockwood”.The British Journal for the Philosophy of Science47.2 (1996), pp. 222–228. 43

  42. [42]

    Why Bohm’s quantum theory?

    H Dieter Zeh. “Why Bohm’s quantum theory?”Foundations of Physics Letters12.2 (1999), pp. 197–200

  43. [43]

    Cambridge University Press, 2009

    Judea Pearl.Causality. Cambridge University Press, 2009

  44. [44]

    A new topology for curved space–time which incorporates the causal, differential, and conformal structures

    Stephen W Hawking, Andrew R King, and Patrick J McCarthy. “A new topology for curved space–time which incorporates the causal, differential, and conformal structures”. Journal of Mathematical Physics17.2 (1976), pp. 174–181

  45. [45]

    The class of continuous timelike curves determines the topology of spacetime

    David B Malament. “The class of continuous timelike curves determines the topology of spacetime”.Journal of Mathematical Physics18.7 (1977), pp. 1399–1404

  46. [46]

    Thecausalsetapproachtoquantumgravity

    SumatiSurya.“Thecausalsetapproachtoquantumgravity”.Living Reviews in Relativity 22.1 (2019)

  47. [47]

    Dynamics of the dissipative two-state system

    Anthony J Leggett, S Chakravarty, Alan T Dorsey, Matthew PA Fisher, Anupam Garg, and Wilhelm Zwerger. “Dynamics of the dissipative two-state system”.Reviews of Modern Physics59 (1987), pp. 1–85

  48. [48]

    Path integral approach to quantum Brownian motion

    Amir O Caldeira and Anthony J Leggett. “Path integral approach to quantum Brownian motion”.Physica A121.3 (1983), pp. 587–616

  49. [49]

    Quantum Brownian motion in a general environment: Exact master equation with nonlocal dissipation and colored noise

    Bei Lok Hu, Juan Pablo Paz, and Yuhong Zhang. “Quantum Brownian motion in a general environment: Exact master equation with nonlocal dissipation and colored noise”. Physical Review D45.8 (1992), pp. 2843–2861

  50. [50]

    The emergence of classical properties through interaction with the environment

    Eric Joos and H Dieter Zeh. “The emergence of classical properties through interaction with the environment”.Zeitschrift für Physik B Condensed Matter59 (1985), pp. 223– 243

  51. [51]

    Master equation for a quantum particle in a gas

    K. Hornberger. “Master equation for a quantum particle in a gas”.Physical Review Letters 90 (2003), p. 160401

  52. [52]

    Cavity optomechanics

    M. Aspelmeyer, T. J. Kippenberg, and F. Marquardt. “Cavity optomechanics”.Reviews of Modern Physics86 (2014), pp. 1391–1452

  53. [53]

    Intro- duction to quantum noise, measurement, and amplification

    A. A. Clerk, M. H. Devoret, S. M. Girvin, F. Marquardt, and R. J. Schoelkopf. “Intro- duction to quantum noise, measurement, and amplification”.Reviews of Modern Physics 82 (2010), pp. 1155–1208

  54. [54]

    The nitrogen-vacancy colour centre in diamond

    M. W. Doherty, N. B. Manson, P. Delaney, F. Jelezko, J. Wrachtrup, and L. C. L. Hol- lenberg. “The nitrogen-vacancy colour centre in diamond”.Physics Reports528 (2013), pp. 1–45. A On the use of non-Hermitian operators in Section 3 Our discussion of the concepts of accessibility, potential accessibility, and decoherence often assumes that we are dealing w...

  55. [55]

    If{P i S}is incompatible with some other projective decomposition{Q k S}, then{Q k S} exerts an interference influence on at least one projective decomposition onG:∃i, k: [P i S, Qk S]̸= 0 =⇒ {Q k S} U − → {Pj G}

  56. [56]

    past”) is the bottom-right input to the circuit andF(for “future

    Any other decomposition{Rl S}satisfying (1) and (2) is a coarse-graining of{Pi S}, in the sense that{R l S} ⊆span C({P i S}). The unique projective decomposition that satisfies all three conditions is calledpreferred. We denote it bySU prefG, using the calligraphic symbolSto avoid confusing this projective decom- position with an algebra (which would be r...