Comment on "Controlling the dynamical evolution of quantum coherence and quantum correlations in $e^{+} e^{-} \rightarrow \Lambda \bar{\Lambda}$ processes at BESIII''

This paper critically refutes recent claims regarding quantum coherence and steering in $e^{+} e^{-} \rightarrow \Lambda \bar{\Lambda}$ processes at BESIII, arguing that the application of open quantum system techniques and the interpretation of quantum correlations are physically unjustified because the produced hyperons are free, unstable particles that do not interact with a common environment.

The Gist

Imagine two scientists, Jaloum and Amazioug, recently published a paper claiming they found a way to "control" how quantum magic (like coherence and steering) changes over time in a specific particle collision at the BESIII lab. They used complex math to say these particles act like a team of two (a bipartite system) that is slowly losing its quantum connection due to "noise" from their environment, similar to how a radio signal gets fuzzy.

Saeed Haddadi, the author of this new commentary, is raising a huge red flag. He argues that the original paper is trying to use a tool designed for one type of problem to solve a completely different one. Here is the breakdown of his critique using simple analogies:

1. The "Shared Room" vs. The "Solo Runners"

The Original Claim: The researchers treated the two particles (a Lambda and an anti-Lambda) as if they were two people sitting in the same room, sharing a noisy environment that affects them both at the same time. In quantum physics, this is called an "open system" where a "bath" or environment causes the particles to lose their special connection.

Haddadi's Counter: Haddadi says this is physically impossible. Once these particles are created in the collision, they are like two sprinters who have just been fired from a starting gun. They immediately zoom off in opposite directions at near light speed. They are free and unstable. They do not stay in a shared room, and they do not interact with a common "bath" or environment after they are born.

• The Analogy: Imagine two runners starting a race. The original paper tries to model them as if they are running through a thick, shared fog that slows them down together. Haddadi says, "No, they are running in a vacuum. There is no fog. Modeling them as if they are in a fog is just making up a story that doesn't match reality."

2. The "Memory" Problem

The Original Claim: The paper discusses "non-Markovian dynamics." In simple terms, this is a fancy way of saying the system has a "memory." It suggests the particles' future behavior depends on their past interactions with the environment, like a ball bouncing on a trampoline that remembers how hard it was hit.

Haddadi's Counter: Since there is no shared environment (no "trampoline" or "fog"), there is no memory to speak of. The particles simply decay (break apart) because of their own internal instability, not because of outside noise.

• The Analogy: Calling this "non-Markovian" is like saying a falling apple has a "memory" of the wind because it fell slowly. Haddadi argues the apple is just falling due to gravity; there is no wind to remember. Applying these complex "memory" labels is just math for math's sake, not physics.

3. The "Remote Control" Issue

The Original Claim: The paper calculates something called "Quantum Steering." This is a specific type of quantum link where one person (Alice) can "steer" or influence the state of a distant particle (Bob) by making a measurement on her end. It's like Alice flipping a switch that instantly changes Bob's lightbulb.

Haddadi's Counter: To prove "steering," you need to be able to choose how to measure the particle in real-time and see how it changes the other one. But with these particles:

1. We can't touch them directly; we only see what they leave behind when they explode (decay).
2. We can't choose to measure them in different ways while they are flying; the experiment is already set.
3. We can't run a "protocol" to test this.

• The Analogy: It's like trying to prove you can steer a car by looking at the tire tracks left on the road after the car has already crashed and disappeared. You can't steer a ghost. Calculating "steering" here is mathematically possible but physically meaningless because you can't actually perform the steering experiment.

4. Math vs. Reality

Haddadi's main point is that the original authors are confusing math with physics.

• The Math: You can take a picture of the particles' spin (their orientation) and plug it into a formula to get a number for "coherence" or "discord."
• The Reality: That number doesn't represent a resource you can use, control, or store. It's just a static snapshot of a moment in time.
• The Analogy: It's like calculating the "fuel efficiency" of a car that has already been scrapped and melted down. The math works, but the car isn't actually driving anywhere, so the efficiency rating doesn't mean anything in the real world.

The Bottom Line

Haddadi concludes that the original paper is building a beautiful, complex castle on a foundation of sand. By treating free-flying, unstable particles as if they are a controlled, noisy system in a lab, the authors have drawn conclusions that are "conceptually ill-defined."

He isn't saying the math is wrong; he is saying the story they are telling about what the math represents is wrong. The particles aren't interacting with a shared environment, they aren't being "steered," and they aren't evolving through a noisy channel. Therefore, the claims about controlling their quantum behavior are not physically real.

Technical Summary

Based on the provided text, here is a detailed technical summary of the paper "Comment on 'Controlling the dynamical evolution of quantum coherence and quantum correlations in e+e−→Λ¯Λ processes at BESIII'" by Saeed Haddadi.

1. Problem Statement

The paper addresses a critical theoretical inconsistency in a recent study (Jaloum & Amazioug, Phys. Rev. D 113, 016024, 2026) that applied quantum information theory to the hyperon–antihyperon system produced in the process $e^+e^- \to \Lambda\bar{\Lambda}$ at the BESIII experiment.

The core problem identified by Haddadi is the misapplication of open quantum system frameworks to a high-energy particle physics context. The original study treated the produced $\Lambda\bar{\Lambda}$ pair as a bipartite system evolving under correlated quantum channels (Markovian and non-Markovian) to analyze the dynamical evolution of coherence, entanglement, and quantum steering. Haddadi argues that this modeling is physically unjustified because the physical nature of the $\Lambda\bar{\Lambda}$ system contradicts the fundamental assumptions required for such quantum information protocols.

2. Methodology and Analytical Approach

Haddadi employs a critical theoretical analysis based on the principles of relativistic quantum mechanics, particle physics phenomenology, and the operational definitions of quantum information theory. The methodology involves:

• Physical Reality Check: Comparing the assumptions of the original study (correlated environments, tunable noise channels) against the actual physical behavior of unstable relativistic particles produced in scattering events.
• Operational Definition Analysis: Evaluating whether the concepts of "quantum steering" and "non-Markovianity" can be operationally defined for the specific experimental constraints of the $\Lambda\bar{\Lambda}$ system.
• Distinction between Formalism and Physics: Differentiating between mathematical quantifiers (which can be computed from a density matrix) and physically realizable quantum resources (which require specific control and interaction scenarios).

3. Key Contributions and Arguments

The paper presents four primary arguments (Remarks) and one main point that dismantle the validity of the original study's framework:

• Remark 1: Lack of a Common Environment:
  The $\Lambda\bar{\Lambda}$ pair is generated in a single scattering event and propagates as two free, unstable particles. Unlike standard open quantum systems where subsystems interact with a shared bath or engineered environment, these particles do not interact with a common environment after production. Therefore, modeling their evolution via correlated quantum channels is physically baseless.

• Remark 2: Misinterpretation of Non-Markovianity:
  The classification of the system's dynamics as "Markovian" or "non-Markovian" is conceptually misleading. Non-Markovianity relies on information backflow from a structured environment. Since the $\Lambda$ hyperon decay is governed by intrinsic weak-interaction lifetimes rather than environmental decoherence, there is no physical memory kernel or bath correlation function to support such a classification.

• Remark 3: Conceptual Invalidity of Quantum Steering:
  Quantum steering is an operational resource requiring: (i) local measurements by one party, (ii) a well-defined state-update rule, and (iii) a controllable scenario. For $\Lambda$ hyperons:

  • Measurements are indirect (inferred from decay products).
  • There is no real-time freedom to choose measurement settings.
  • No operational steering protocol can be implemented.
    Consequently, calculating steering measures for this system is conceptually ill-defined and does not correspond to any realizable quantum task.

• Remark 4: Conflation of Mathematical and Physical Quantities:
  The original study conflates mathematical quantifiers (e.g., geometric discord, coherence measures) with physical quantum resources. While one can mathematically compute these from a reconstructed density matrix, these correlations in high-energy physics are static statistical objects fixed at the moment of production. They do not represent dynamically evolving resources subject to quantum control, storage, or processing.

• Main Point: The Nature of the "Channel":
  The fundamental error lies in treating hadronization or detector interactions as a "tunable correlated noise channel" acting on a pre-existing two-qubit state. Hadronization is a non-perturbative QCD process that creates the baryons; it is not an external dynamical map. Similarly, detector interactions occur after the state is fixed. The spin density matrix extracted from decay distributions is a static statistical object, not a dynamical state undergoing engineered decoherence.

4. Results

• The application of open quantum system techniques (Markovian/non-Markovian channels) to the $e^+e^- \to \Lambda\bar{\Lambda}$ process is physically unsupported.
• The reported hierarchy of quantum correlations (steering, entanglement, discord, coherence) and their "dynamical evolution" under abstract noise parameters are incorrect interpretations of the physical reality.
• The concept of "controlling" the dynamical evolution of these correlations in this specific system is operationally impossible due to the lack of a controllable environment and measurement freedom.

5. Significance

• Theoretical Rigor: The paper emphasizes the necessity of distinguishing between formal mathematical tools and physically realizable protocols in high-energy physics. It warns against the "over-interpretation" of quantum information metrics in contexts where the operational prerequisites (control, environment, measurement freedom) are absent.
• Correction of Literature: It serves as a critical correction to recent literature that may have misapplied quantum information concepts to particle physics, potentially misleading the community regarding the nature of quantum resources in unstable particle systems.
• Future Directions: It calls for a more careful approach when analyzing spin correlations in particle physics, suggesting that such correlations should be treated as static production kinematics rather than dynamically evolving quantum information resources subject to decoherence models.