The impact of a measurement on an open quantum system

C.J. Muller

REVIEW 4 major objections 5 minor 8 references

The impact of a measurement on an open quantum system

T0 review · 4 major / 5 minor · reviewed 2026-08-12 · deepseek-v4-flash

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Pith's one-line read A partially wet molecular junction senses each measurement outcome and prepares the opposite state for the next measurement.

desk verdict A potentially interesting empirical pattern buried under a post hoc model that contradicts itself; the core claim of measurement-induced fixed sequences is not established. read the letter →

arxiv 2412.04481 v1 pith:YCYWPA53 submitted 2024-11-20 cond-mat.mes-hall

C.J. Muller This is my paper · ORCID

classification cond-mat.mes-hall

keywords openquantumsystemsnon-Markoviandynamicsmeasurementback-actionmolecularbreakjunctionpartiallywetphasecurrent-carryingstatesmemoryeffectscurrent-voltagespectroscopy

topics The Measurement Problem

open problems The Measurement Problem

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

This paper claims that a molecular mechanically controllable break junction in the partially wet phase behaves as an open quantum system in which one measurement determines the outcome of the next one. The molecule's information leaks into a controlled wet layer that can feed it back, and a measurement removes only the leaked character that it records, leaving the complementary character to flow back and steer the next reading. The data show two-state alternation and, when three or four current-carrying states are visible, a fixed cyclic sequence of states carrying the current. If correct, the measurements demonstrate that memory effects, not ordinary stochastic averaging, drive the pattern.

What carries the argument

The central object is the system-controlled-environment cycle: a quantum system S, the molecule between two gold electrodes, coupled to a controlled environment CE formed by floating charges on the tetrahydrofuran partially wet phase layer. Information leaks from S to CE and can flow back, and a measurement acts on CE rather than on S, deleting only the measured state character so that the complementary character backflows and biases the next measurement. The experimental counterpart is the state-curve, a group of measurement points that belong to one current-carrying state, whose order in the data exposes the alternation or fixed sequence.

What would settle it

A decisive test is to vary the dwell time per measurement point in the same partially wet phase junction: at dwell times much shorter or much longer than the 45 ms used here, the alternating or fixed state sequence should weaken or become stochastic if backflow timing controls it, while unchanged sequences would rule out the backflow timescale as the mechanism.

Watch

Extended reading notes

Core claim

In the author's terms, the quantum system senses the measurement outcome and prepares itself in a state other than the state related to that outcome. The measured current state's leaked information is erased in the controlled environment, while the complementary information returns to the molecule and bolsters the state that the next measurement records. For two states this gives alternation; for three or four states it gives a fixed sequence, and the paper reports exactly such sequences across three bending beam assemblies, including a four-state series that repeats red-blue-green-purple over the whole voltage range in which the states exist. The paper concludes that non-Markovianity, or memory effects, is responsible for the observations, and that the partially wet phase junction offers an experimental window onto the measurement problem.

Load-bearing premise

The load-bearing premise is that a measurement acts on the wet layer around the molecule rather than on the molecule itself, erasing only the character it records and leaving the opposite character to flow back and steer the next measurement; if measurements instead act directly on the molecule, the predicted alternation does not follow.

Editorial extensions

If this is right

Each point in these IV curves conditions the following point, so the trace cannot be treated as an average over independent stochastic events.
Two, three, or four current-carrying states can appear as state-curves with a fixed cyclic order that persists over the full voltage range in which the states exist.
The measurement acts as a sink of information within the controlled environment, so the environmental memory, not the molecule alone, determines the next reading.
New states are generated or deleted at the nodes of the min-max current bandwidth oscillation, connecting the number of observable states to a voltage-dependent bandwidth envelope.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

A scan-speed series, with dwell times much shorter and much longer than the 45 ms used here, would map the backflow timescale and directly test whether the 45 ms timing is essential; the paper itself calls for varied scan speeds.
If the model is correct, color-coded state-curves are classical readouts of a hidden cyclic state of the coupled molecule-environment system, so timestamped current traces could serve as a single-junction probe of non-Markovian memory.
The equal-leak-rate assumption used for the three- and four-state sequences predicts that the sequence order is fixed but that unequal leak rates would break it; measuring how long each state persists would reveal such an asymmetry.

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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

Quick take: the red-blue-green-purple alternation in Fig. 6 is genuinely unusual and I don't recall seeing that in the MCB literature. That part is worth taking seriously. But the paper's own explanation for it doesn't survive scrutiny, and the evidence is otherwise too thin to carry the conclusion.

What the paper does well: the experimental setup is described carefully, the author is openly uncertain about what exactly the quantum system is, and three separate bending-beam assemblies are shown to exhibit similar patterns. The observation that consecutive IV points cycle through discrete state-curves in a fixed order—if real—would be a new experimental phenomenon.

Now the soft spots. The stress-test is right: the three-state argument in Section 3 is internally inconsistent. The author assumes equal leak rates, picks |B> as first measured, then says the next is |A> "or |C>", picks |A>, then says the third is |C> because |C> has been building up longest. But under equal leak rates, at the first measurement all three states have leaked for the same duration, so |A> and |C> are symmetric; nothing selects |A> over |C>. And after |C> is measured third, |B> has been replenishing for two steps while |A> only one, so the fourth should be |B>, not |A> as claimed. The four-state case is not derived at all—the fixed cycle red-blue-green-purple is just asserted. That flaw sits in the mechanism the abstract and conclusions rest on.

Beyond that, the empirical case is weak: no error bars, no statistical test, no control experiment, no data or code. The model is assembled after the fact—the number of states, the equal-leak-rate assumption, and the sequence are all chosen to match the observed pattern. The unproven postulate that measurement acts on the controlled environment rather than on the system is doing all the work.

Proportion matters here: I'm not saying the observation is fake. It might be real and important. But the paper does not demonstrate it, and the proposed mechanism, as written, cannot explain the fixed sequence even under its own assumptions.

Recommendation: if this crosses your desk, don't desk-reject without thinking. Send it to a referee who knows MCB junctions and open quantum systems, because the empirical claim deserves a careful look. But as a referee I'd reject the current version; the author needs controlled experiments, real statistics, and a model that actually derives the cycle before the claim is credible.

Referee Report

4 major / 5 minor

Summary. The paper reports current-voltage measurements on a molecular mechanically controllable break junction in the partially wet phase, claiming that consecutive measurement points reveal discrete current-carrying states whose measurement order is influenced by the previous measurement. For two states the paper claims an alternation, and for three or four states it claims a fixed measurement sequence (e.g., red, blue, green, purple, red, ... in Fig. 6). The theoretical discussion (Section 3, Figs. 8 and 9) proposes that the quantum system S couples to a controlled environment CE, that a measurement acts on CE rather than on S, deleting only the measured state character, and that backflow of the remaining complementary information biases the next measurement. The paper concludes that these effects are due to non-Markovian memory effects and that the measurement itself determines the next measurement.

Significance. If the experimental claims were substantiated, the observation of measurement-controlled, deterministic-looking alternation between discrete current states in a molecular junction would be a striking contribution to the study of open quantum systems and the quantum-to-classical transition. The paper is clearly written and presents an intriguing hypothesis with an explicit pictographic mechanism. However, the evidence as presented is exclusively visual: no error bars, no statistical tests, no control experiments, and no data or code release are provided. More importantly, the proposed mechanism for the fixed three-state sequence is internally inconsistent under the paper's own assumptions, and the central postulate that 'a measurement acts on CE, not on S' is asserted without independent justification. The model is assembled after the data are observed, with the number of states, the equal-leak-rate assumption, and the sequence order chosen to match the color-coded patterns. The paper therefore does not currently meet the evidentiary and logical standards required for a journal publication.

major comments (4)

[Section 3, after Fig. 9] The explanation of the fixed three-state sequence is internally inconsistent with the equal-leak-rate assumption stated in the same paragraph. Immediately before the first measurement, all three states |A>, |B>, and |C> have leaked into the controlled environment for the same duration, so after |B> is removed |A> and |C> have equal CE populations; there is no basis to select |A> as the second measurement. Similarly, after |C> is measured, |B> has been replenishing for exactly as long as |A> (both were measured earlier), yet the text claims the next measurement is |A> again, not |B>. Thus the claimed sequence B, A, C, A, ... does not follow from the model. Because the fixed-sequence claim appears in the abstract and conclusions, this inconsistency directly undermines the paper's main assertion.
[Section 2, Figs. 2–7] The central empirical claim rests entirely on visual pattern recognition: state-curves are identified by eye, and the ordering of colored points is asserted without any quantitative assignment criterion. No error bars, statistical test, or control experiment is provided to rule out that the observed point ordering is a stochastic fluctuation. The statement in Section 2 that 'the regular pattern ... cannot be attributed to noise' is an assertion, not a demonstrated result. Given the strong claim that 'the measurement itself determines the next one', the absence of any quantitative analysis is a load-bearing omission. The paper also does not provide a data or code release, which prevents independent verification.
[Section 3, Fig. 9] The entire mechanism depends on the postulate that 'a measurement acts on CE, not on S' and that it deletes only the measured |A> or |B> character, leaving the complementary information to flow back. This postulate is stated without derivation, without justification from the experimental setup, and without any independent evidence. If this postulate is wrong, no alternation follows. Since the paper offers no operational description of how the measurement acts on the controlled environment, this is an unsupported axiom rather than a derived consequence, and it is load-bearing for all conclusions.
[Section 3, final paragraphs] The model is post hoc: the number of states (two, three, or four), the equal-leak-rate assumption, and the specific sequence order are chosen after observing the data to match the color-coded patterns. The paper makes no quantitative prediction that could be independently tested, and it explicitly states that 'the definition of "right" remains vague' for the experimental conditions and that the characteristic times (45 ms, 0.5 s) are unclear. A mechanism that requires such hand-selected assumptions and offers no falsifiable prediction cannot support the strong conclusions drawn in the abstract and Section 4.

minor comments (5)

[Abstract] The phrase 'are not known the nature of the experiments' is grammatically incomplete and should be rephrased, for example as 'the exact quantum system, environment, and coupling are not known, the nature of the experiments shows...'.
[Section 3, qe1/qe2 discussion] The phrase 'It is a possibility that the quantum effect reported in 2021 [7] is an entanglement of two quantum effects' seems to use 'entanglement' in a nonstandard way; 'combination' or 'superposition of two effects' would be clearer.
[References] Reference [8] is a progress report deliverable, not a peer-reviewed publication; its status should be stated explicitly in the reference list to avoid implying equal standing with the other references.
[Section 2, Fig. 6] The description that the points advance the previous color by 1 mV and that points within the same color group are 4 mV apart is central to the fixed-sequence claim, but the assignment of colors to individual data points is not documented in a quantitative way; an enlarged panel with explicit indexing would clarify this.
[Throughout] There are several small typos and infelicities, such as 'The stage of such a system at t = t0 is provided by system(t0)' in the Introduction, which should read 'The state of such a system at t = t0 is provided by system(t0)'.

Circularity Check

2 steps flagged · score 6.0 of 10

The fixed-sequence 'explanation' inserts the observed order by hand ('we take |B> ... we take |A>') and then recovers it as a prediction, so the central claimed prediction reduces to the data by construction.

fitted input called prediction [Section 3, paragraph discussing three- and four-state curves (after Fig. 9)]
"It does assuming an equivalent leak rate of information for the three or four states. We can choose any of the three states, |A⟩, |B⟩ or |C⟩ to be the first one measured, we take |B⟩. The next measurement will be |A⟩ or |C⟩ as the |B⟩ character has been effectively removed by the first measurement, we take |A⟩. The third measurement will then be |C⟩ as |C⟩ character has been building up within CE for the longest time. Next measurement will be |A⟩ again for the same reason, and so forth."

The claimed fixed sequence is not derived from the equal-leak-rate assumption. Immediately before the first measurement all three states have leaked for the same duration, so there is no reason in the model to select |B⟩ first. After |B⟩ is removed, |A⟩ and |C⟩ have equally long build-up, so choosing |A⟩ over |C⟩ as the second measurement is also underdetermined. The 'we take' choices therefore insert exactly the observed ordering by hand; the text then presents the inserted order as the explained/predicted sequence. Because any observed ordering could be reproduced by making the corresponding arbitrary first choices, the explanation reduces to restating the data rather than predicting it.
self definitional [Section 3, Fig. 9 and surrounding pictographic-tomography paragraph]
"The four indicated situations, I to IV , represent a measurement cycle containing two different measurements indicated by the encircled "M's". This cycle constitutes the origin of the observed alternating measurements. ... The important aspect here is that the measurement equipment can only measure |A⟩ or |B⟩ character, removing one and leaving the other."

The two-state 'alternation' is put into the model as the defining behavior of the measurement cycle: one measurement removes |B⟩-character from the controlled environment, the next removes |A⟩-character, and this is then called the origin of the observed alternating measurements. That is not an independent derivation from the non-Markovian premise; it is the alternation itself restated as a mechanism. The cycle is specified in terms of alternating measurements, so the conclusion 'alternating measurements occur' is equivalent to the assumed deletion rule by construction.

full rationale

The paper's experimental observations are real and independent of the model, but the model's central explanatory claim—that measurement-induced deletion of one state's leaked character forces the next measurement to be of another state—is a postulate that already contains the alternation it is meant to explain. The circularity becomes most concrete in the three- and four-state case: the fixed sequence is not deduced from equal leak rates, since equal leak rates leave the first two choices completely undetermined; instead, the text chooses |B⟩ first and |A⟩ second to match the observed order, then presents the resulting sequence as the predicted one. This is a fitted input called a prediction. The paper also contains an internal inconsistency (equal leak rates give no basis for preferring |A⟩ over |C⟩ after |B⟩ is removed), which underscores that no derivation is actually present. The self-citation to the author's earlier setup paper [7] is not load-bearing for the theoretical mechanism; it supplies experimental context. However, the absence of any quantitative, parameter-free test of the model means the claimed 'fixed sequence' explanation has no independent content beyond the data it was assembled to match. Score 6 reflects partial circularity of the central explanatory claim, while the experimental data and the qualitative two-state mechanism retain some independent descriptive content.

Assumptions & free parameters 1 free parameters · 5 assumptions · 0 invented entities

The central explanation rests on several unverified physical postulates: an information-preserving environment, measurement deleting only one state component, equal leak rates across states, and the identification of IV bands with discrete quantum states. No independent evidence for these postulates is presented within the paper.

free parameters (1)

per-state information leak rate = not quantified; assumed equal across states
Section 3: 'assuming an equivalent leak rate of information for the three or four states' is introduced specifically to make the observed sequence follow; no independent estimate is given.

assumptions (5)

domain assumption The controlled environment retains all information about the initial quantum system and can return it to the system.
Invoked in Section 3: 'the controlled environment together with the increased decoherent quantum system still contain all the initial quantum system information'. This backflow is central to the mechanism but unproven.
ad hoc to paper A measurement acts on the controlled environment, not on the system, and deletes only the measured |A> or |B> character.
Section 3, Fig. 9: 'a measurement acts on CE, not on S' and 'measurement equipment can only measure |A> or |B> character, removing one and leaving the other'. This postulate is not derived from measurement theory and is load-bearing.
ad hoc to paper Equal leak rates for all current-carrying states in the three- and four-state cases.
Section 3: 'assuming an equivalent leak rate of information...'. The assumption is chosen to reproduce the observed fixed sequence and is not independently measured.
domain assumption Floating charge carriers on the THF partially wet phase form a Faraday cage that electrically isolates the molecule, creating a controlled environment.
Section 1 and Section 3. This is carried over from the author's prior work [7] with no in-paper evidence.
domain assumption The current-carrying states observed as state-curves are distinct quantum states |A>, |B>, etc. of a single molecule.
Section 3: 'Let us assume that the quantum system consists of two states |A> and |B>'. The mapping from bands in the IV curve to quantum states is assumed, not established.

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Cite this review

Pith. "Pith review of The impact of a measurement on an open quantum system." pith.science (2026). https://pith.science/paper/YCYWPA53

@misc{pith2026241204481,
  author       = {Pith},
  title        = {Pith review of: The impact of a measurement on an open quantum system},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/YCYWPA53}},
  note         = {Machine review of arXiv:2412.04481}
}

read the original abstract

A molecular MCB junction in the partially wet phase has been used to probe effects related to open quantum systems. Although the exact quantum system, environment, and coupling, are not known the nature of the experiments shows a measurement influenced next measurement. The quantum system senses the measurement outcome and prepares itself in a state other than the state related to the measurement outcome. This triggers an alternation of measurements which are indicative of two current carrying states. In case three or more current carrying states are observed, there exists a fixed sequence of states that carry the current. We conclude that memory effects in these systems are responsible for these experimental observations.

Figures

Figures reproduced from arXiv: 2412.04481 by the authors.

**Figure 6.** A distinction in four groups of data is visible as [PITH_FULL_IMAGE:figures/full_fig_p004_6.png] view at source ↗

**Figure 5.** A considerable reduced average current in this IV [PITH_FULL_IMAGE:figures/full_fig_p004_5.png] view at source ↗

Figures from the paper (2 more)

**Figure 8.** Figure 8: A schematic representation of the quantum system [PITH_FULL_IMAGE:figures/full_fig_p005_8.png]

**Figure 9.** Figure 9: Pictographic tomography of the influence of a measurement on a non-Markovian system. The four indicated [PITH_FULL_IMAGE:figures/full_fig_p006_9.png]

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

8 extracted references · 8 canonical work pages

[1]

Decoherence, einselection, and the quan- tum origins of the classical

WH Zurek. Decoherence, einselection, and the quan- tum origins of the classical. Rev. Mod. Phys., 75:715– 775, May 2003

work page 2003
[2]

Quantum darwinism

WH Zurek. Quantum darwinism. Nature physics, 5(3):181–188, 2009

work page 2009
[3]

Decoherence, the measurement prob- lem, and interpretations of quantum mechanics

M Schlosshauer. Decoherence, the measurement prob- lem, and interpretations of quantum mechanics. Re- views of Modern physics, 76(4):1267–1305, 2004

work page 2004
[4]

The theory of open quan- tum systems

H Breuer and F Petruccione. The theory of open quan- tum systems. 2002

work page 2002
[5]

Tomographically recon- structed master equations for any open quantum dy- namics

FA Pollock and K Modi. Tomographically recon- structed master equations for any open quantum dy- namics. Quantum, 2:76, 2018

work page 2018
[6]

Operational approach to open dynamics and quantifying initial correlations

K Modi. Operational approach to open dynamics and quantifying initial correlations. Scientific reports, 2(1):581, 2012

work page 2012
[7]

Decoupling environmental modes from tunneling electrons in a partially wet phase molecular mechanically controllable break junction

CJ Muller. Decoupling environmental modes from tunneling electrons in a partially wet phase molecu- lar mechanically controllable break junction. arXiv preprint arXiv:2106.01716, 2021

work page Pith review arXiv 2021
[8]

Progress report theoretical investiga- tion on the capability of quantum probing of bosonic networks using single or multiple probes

Deliverable 5.2:. Progress report theoretical investiga- tion on the capability of quantum probing of bosonic networks using single or multiple probes. March 28, 2017. 7

work page 2017

Pith tools

Reviewed August 12, 2026 · model on record in the stance chip above.

[1] [1]

Decoherence, einselection, and the quan- tum origins of the classical

WH Zurek. Decoherence, einselection, and the quan- tum origins of the classical. Rev. Mod. Phys., 75:715– 775, May 2003

work page 2003

[2] [2]

Quantum darwinism

WH Zurek. Quantum darwinism. Nature physics, 5(3):181–188, 2009

work page 2009

[3] [3]

Decoherence, the measurement prob- lem, and interpretations of quantum mechanics

M Schlosshauer. Decoherence, the measurement prob- lem, and interpretations of quantum mechanics. Re- views of Modern physics, 76(4):1267–1305, 2004

work page 2004

[4] [4]

The theory of open quan- tum systems

H Breuer and F Petruccione. The theory of open quan- tum systems. 2002

work page 2002

[5] [5]

Tomographically recon- structed master equations for any open quantum dy- namics

FA Pollock and K Modi. Tomographically recon- structed master equations for any open quantum dy- namics. Quantum, 2:76, 2018

work page 2018

[6] [6]

Operational approach to open dynamics and quantifying initial correlations

K Modi. Operational approach to open dynamics and quantifying initial correlations. Scientific reports, 2(1):581, 2012

work page 2012

[7] [7]

Decoupling environmental modes from tunneling electrons in a partially wet phase molecular mechanically controllable break junction

CJ Muller. Decoupling environmental modes from tunneling electrons in a partially wet phase molecu- lar mechanically controllable break junction. arXiv preprint arXiv:2106.01716, 2021

work page Pith review arXiv 2021

[8] [8]

Progress report theoretical investiga- tion on the capability of quantum probing of bosonic networks using single or multiple probes

Deliverable 5.2:. Progress report theoretical investiga- tion on the capability of quantum probing of bosonic networks using single or multiple probes. March 28, 2017. 7

work page 2017