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arxiv: 2607.01786 · v1 · pith:ULTOELCK · submitted 2026-07-02 · quant-ph · physics.optics

Performance of a two-mode coherent superposed channel in continuous-variable quantum teleportation

Deepak , Arpita Chatterjee This is my paper

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classification quant-ph physics.optics
keywords two-mode coherent statessuperposed quantum statescontinuous-variable teleportationnonclassicalitynon-GaussianityWigner functionquantum fidelityBraunstein-Kimble protocol
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The pith

The two-mode coherent superposed state achieves continuous-variable teleportation fidelities above the classical threshold in certain parameter regimes.

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

This paper introduces a two-mode coherent superposed state generated by applying a superposition operator to two-mode coherent states. It examines the state's nonclassicality and non-Gaussianity using the Wigner distribution and Wigner logarithmic negativity. The state is then used as the entangled resource in the Braunstein-Kimble protocol to teleport coherent and squeezed inputs. The analysis shows that in parameter regimes with stronger non-Gaussian features or nonclassicality, the teleportation fidelity can surpass the classical limit of one half.

Core claim

The two-mode coherent superposed quantum state, produced by the action of the operator A = t a b + r a† b† on the two-mode coherent state |α, β>, exhibits nonclassicality and quantum non-Gaussianity as quantified by the Wigner distribution and Wigner logarithmic negativity. When employed as the entangled resource in the ideal Braunstein-Kimble continuous-variable teleportation protocol, this state yields teleportation fidelities for coherent and squeezed inputs that exceed the classical threshold in specific parameter regimes where the non-Gaussian features or nonclassicality are enhanced.

What carries the argument

The two-mode superposition operator A = t a b + r a† b† applied to two-mode coherent states to create the entangled resource, with the Wigner logarithmic negativity serving as the measure linking non-Gaussianity to teleportation performance.

If this is right

  • Fidelities for coherent and squeezed inputs exceed the classical threshold in regimes of enhanced non-Gaussianity.
  • Increased nonclassicality correlates with higher teleportation efficiency.
  • The results demonstrate the operational significance of such engineered states in CV quantum information processing.
  • The ideal teleportation fidelity depends on the strengths of nonclassicality and non-Gaussianity.

Where Pith is reading between the lines

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

  • This suggests testing the state in other continuous-variable protocols such as entanglement swapping.
  • Experimental generation of the state via the described operator might be feasible with current linear optics.
  • The assumption of an ideal protocol means real-world noise could reduce the observed advantage.
  • Comparing fidelity improvements to those from other non-Gaussian resources like cat states would be informative.

Load-bearing premise

The nonclassicality and non-Gaussianity of the state, as measured by the Wigner function and its logarithmic negativity, directly translate to higher teleportation fidelity in the ideal Braunstein-Kimble protocol.

What would settle it

A direct computation of the teleportation fidelity from the Wigner function of the resource state that finds the fidelity stays at or below one half even in regimes of large Wigner logarithmic negativity.

Figures

Figures reproduced from arXiv: 2607.01786 by Arpita Chatterjee, Deepak.

Figure 1
Figure 1. Figure 1: FIG. 1. A comparison of Wigner function for [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Wigner logarithmic negativity with respect to state [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Variation of fidelity with coherent state input and wi [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Variation of fidelity with squeezed state input ( [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗
read the original abstract

Glauber's coherent state is denoted by $\ket{\alpha}$ and its two-mode extension is represented by $\ket{\alpha,\beta}$. In this work, we introduce a two-mode superposition operator $A=tab+ra^\dagger b^\dagger$, whose action on the two-mode coherent state produces the two-mode coherent superposed quantum state $\ket{\psi}=(tab+ra^\dagger b^\dagger)\ket{\alpha,\beta}$. We investigate the nonclassicality and quantum non-Gaussianity of this state by means of the Wigner distribution and Wigner logarithmic negativity. Once its intrinsic nonclassical and non-Gaussian structure is established, the state is employed as the entangled resource in the Braunstein-Kimble continuous-variable (CV) teleportation protocol. We compute the ideal teleportation fidelity for coherent and squeezed inputs and analyze how the strengths of nonclassicality and non-Gaussianity influence the teleportation efficiency. Our results identify specific parameter regimes where enhanced non-Gaussian features or increased nonclassicality enable fidelities beyond the classical threshold, thereby revealing the operational significance of engineered two-mode quantum states in CV quantum information processing.

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

2 major / 2 minor

Summary. The paper defines a two-mode coherent superposed state |ψ⟩ = (t ab + r a†b†)|α,β⟩, quantifies its nonclassicality and non-Gaussianity via the Wigner distribution and Wigner logarithmic negativity, and inserts it as the entangled resource into the ideal Braunstein-Kimble CV teleportation protocol. Fidelity is computed for coherent and squeezed inputs via overlap integrals or characteristic functions, with the central claim that regimes of enhanced WLN yield F > 1/2 (classical threshold), thereby demonstrating the operational value of such engineered states.

Significance. If the results hold after isolating the role of non-Gaussianity, the work would establish concrete parameter regimes in which non-Gaussian two-mode resources improve CV teleportation performance, providing a useful benchmark for experiments with engineered continuous-variable states.

major comments (2)
  1. [Teleportation fidelity section] The fidelity calculation (described after the WLN definition) reports F > 1/2 in high-WLN regimes, but t, r, α, β simultaneously tune both WLN and two-mode entanglement (via reduced covariance or logarithmic negativity). No comparison is made to a Gaussian state with matched entanglement, so the observed correlation does not establish that non-Gaussianity is the causal driver of the fidelity gain.
  2. [Results and discussion] The claim that 'enhanced non-Gaussian features enable fidelities beyond the classical threshold' (final paragraph) rests on the assumption that WLN directly improves teleportation efficiency in the Braunstein-Kimble protocol, yet the manuscript provides no control calculation or partial derivative isolating WLN from entanglement at fixed parameters.
minor comments (2)
  1. [State definition] The normalization constant for |ψ⟩ is not stated explicitly after the definition of A; this should be added to allow reproduction of the Wigner function.
  2. [Figures] Figure captions for fidelity plots should include the classical threshold F = 1/2 as a reference line.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and constructive comments. The concerns regarding the need to isolate non-Gaussianity from entanglement in the fidelity analysis are valid, and we address each point below with plans for revision.

read point-by-point responses

  1. Referee: [Teleportation fidelity section] The fidelity calculation (described after the WLN definition) reports F > 1/2 in high-WLN regimes, but t, r, α, β simultaneously tune both WLN and two-mode entanglement (via reduced covariance or logarithmic negativity). No comparison is made to a Gaussian state with matched entanglement, so the observed correlation does not establish that non-Gaussianity is the causal driver of the fidelity gain.

    Authors: We agree that the current results demonstrate a correlation between high WLN and F > 1/2 but do not isolate causality from entanglement. In the revised manuscript we will add explicit comparisons to two-mode squeezed vacuum states with logarithmic negativity matched to selected points of our non-Gaussian states, recomputing fidelities to quantify any additional gain attributable to non-Gaussianity. revision: yes

  2. Referee: [Results and discussion] The claim that 'enhanced non-Gaussian features enable fidelities beyond the classical threshold' (final paragraph) rests on the assumption that WLN directly improves teleportation efficiency in the Braunstein-Kimble protocol, yet the manuscript provides no control calculation or partial derivative isolating WLN from entanglement at fixed parameters.

    Authors: The referee is correct that no such control is present. We will revise the Results and discussion section to include control calculations that hold entanglement (logarithmic negativity) fixed while varying WLN, or direct side-by-side fidelity comparisons against Gaussian resources at matched entanglement, thereby qualifying the claim appropriately. revision: yes

Circularity Check

0 steps flagged

No circularity detected; derivation is a direct computational pipeline

full rationale

The paper defines the state |ψ⟩ via the operator A acting on |α,β⟩, computes its Wigner function and WLN using standard definitions, then evaluates teleportation fidelity in the Braunstein-Kimble protocol via overlap or characteristic function. Fidelity is obtained directly from the state parameters without any fitted input renamed as prediction, self-definitional loop, or load-bearing self-citation. The reported correlation between non-Gaussianity and fidelity >1/2 is an analysis of computed quantities, not a claim that one is constructed from the other. The chain is self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

4 free parameters · 2 axioms · 1 invented entities

The central claim rests on the definition of the new operator, the assumption that the generated state remains normalizable, and the premise that Wigner-based measures of nonclassicality and non-Gaussianity are the relevant predictors of teleportation performance. No external benchmarks or machine-checked derivations are mentioned.

free parameters (4)
  • t
    Weight of the a b term in the superposition operator A
  • r
    Weight of the a† b† term in the superposition operator A
  • α
    Amplitude of the first coherent mode
  • β
    Amplitude of the second coherent mode
axioms (2)
  • standard math Two-mode coherent states |α,β⟩ are valid quantum states
    Standard background fact in quantum optics
  • domain assumption The operator A produces a normalizable state suitable for use as an entangled resource
    Required for the state |ψ⟩ to be physically usable in the teleportation protocol
invented entities (1)
  • two-mode coherent superposed state |ψ⟩ no independent evidence
    purpose: Entangled resource for CV teleportation
    New state introduced by the operator A; no independent experimental evidence supplied in the abstract

pith-pipeline@v0.9.1-grok · 5729 in / 1515 out tokens · 69286 ms · 2026-07-03T12:42:09.231212+00:00 · methodology

discussion (0)

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Reference graph

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