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arxiv: 2606.17251 · v1 · pith:UPPS5BMQnew · submitted 2026-06-15 · 🪐 quant-ph · cond-mat.quant-gas

Post-Selection Probability and Fidelity of Bidirectional Teleportation

Pith reviewed 2026-06-27 03:17 UTC · model grok-4.3

classification 🪐 quant-ph cond-mat.quant-gas
keywords bidirectional teleportationpost-selection probabilityfidelityLoschmidt echointegrable modelsquantum scramblingquantum information processing
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The pith

The post-selection probability and fidelity of bidirectional teleportation are expressed using Loschmidt echoes, revealing initial-state dependence and stability in integrable models.

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

The paper shows that the post-selection probability and the fidelity characterizing a bidirectional teleportation protocol can be rewritten using the Loschmidt echo and its subsystem variant from quantum dynamics. This holds even when errors occur in the time-reversed part of the protocol. A reader would care because the rewriting explains why fidelity changes with the initial state and why the probability remains steady in integrable systems, offering guidance for real-device implementations.

Core claim

The central claim is that the post-selection probability and fidelity of the bidirectional teleportation protocol can be expressed in terms of the Loschmidt echo and its subsystem variant. This expression unveils the initial-state dependence of the fidelity and the stability of the post-selection probability in integrable models, remaining valid with errors in time-reversed dynamics.

What carries the argument

The Loschmidt echo and its subsystem variant, which serve as the bridge connecting the teleportation protocol quantities to standard quantum dynamics diagnostics.

If this is right

  • The fidelity of the teleportation depends on the choice of initial state.
  • The post-selection probability remains stable when the underlying model is integrable.
  • These quantities can be computed from Loschmidt echoes even in the presence of errors.
  • Practical guidance emerges for implementing the protocol on quantum hardware.

Where Pith is reading between the lines

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

  • Measuring Loschmidt echoes could provide a way to estimate teleportation performance without running the full protocol.
  • The stability in integrable models might extend to other post-selection based protocols in quantum information.
  • Testing in chaotic versus integrable regimes could distinguish the behaviors predicted here.

Load-bearing premise

The bidirectional teleportation protocol is implemented via chaotic Hamiltonian evolution combined with measurement and post-selection, and the claimed expressions remain valid when errors are present in the time-reversed dynamics.

What would settle it

Compute or measure the post-selection probability in both an integrable and a chaotic model under the protocol; if the probability changes substantially between them, the stability claim is false.

Figures

Figures reproduced from arXiv: 2606.17251 by Lei Feng, Ning Sun, Pengfei Zhang.

Figure 1
Figure 1. Figure 1: FIG. 1. The schematic illustration of the bidirectional tele [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. The diagrammatic proof of the main relations: (1) [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. We present the numerical results for the quantum [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. We present the numerical results for the quantum [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
read the original abstract

Understanding the scrambling of quantum information is central to many areas of quantum physics, including quantum thermalization, entanglement growth, and quantum information processing. Insights from these studies have, in turn, inspired the development of novel quantum protocols and algorithms. Recently, a bidirectional teleportation protocol was proposed to implement a digital SWAP operation between qubits by leveraging chaotic Hamiltonian evolution combined with measurement and post-selection. In this work, we provide a comprehensive study of two central quantities that characterize the protocol, the post-selection probability and the fidelity, taking into account possible errors in time-reversed dynamics. We show that these quantities can be expressed in terms of standard diagnostics in quantum dynamics, including the Loschmidt echo and its subsystem variant. The results unveil (1) the initial-state dependence of the fidelity and (2) the stability of the post-selection probability in integrable models. Our findings offer practical guidance for the implementation of the protocol on realistic quantum devices.

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

0 major / 2 minor

Summary. The manuscript analyzes the post-selection probability and fidelity of a bidirectional teleportation protocol that employs chaotic Hamiltonian evolution together with measurement and post-selection. It derives exact expressions for these quantities in terms of the Loschmidt echo and its subsystem variant, including the case of errors in the time-reversed dynamics, and uses the expressions to identify the initial-state dependence of the fidelity and the stability of the post-selection probability in integrable models.

Significance. If the claimed mappings hold, the work supplies a direct link between a quantum-information protocol and standard diagnostics of quantum dynamics, thereby offering concrete guidance for experimental realization on noisy devices and clarifying state dependence and integrability effects.

minor comments (2)
  1. [§3] §3 (or wherever the error model is introduced): the precise form of the error operators in the time-reversed dynamics should be stated explicitly so that the reader can verify that the Loschmidt-echo mapping remains exact rather than approximate.
  2. The discussion of integrable models would benefit from a short statement of the specific Hamiltonians or conserved quantities used to demonstrate stability of the post-selection probability.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive assessment of the manuscript, accurate summary of its contributions, and recommendation of minor revision. No specific major comments or points requiring clarification were provided in the report.

Circularity Check

0 steps flagged

No significant circularity

full rationale

The paper maps the post-selection probability and fidelity of the bidirectional teleportation protocol to the Loschmidt echo and its subsystem variant via explicit derivations from the protocol definition (chaotic Hamiltonian evolution plus measurement/post-selection). These are standard, independently defined diagnostics in quantum dynamics, not constructed from the protocol outputs. The initial-state dependence and stability results follow directly from applying the mappings to different Hamiltonians, without any reduction to fitted parameters, self-definitions, or load-bearing self-citations. The full derivations are self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Only abstract available; no explicit free parameters, axioms, or invented entities are stated.

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discussion (0)

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Reference graph

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