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arxiv: 2504.00162 · v2 · submitted 2025-03-31 · 🪐 quant-ph

Quantum inputs in the prepare-and-measure scenario and stochastic teleportation

Elna Svegborn , Jef Pauwels , Armin Tavakoli This is my paper

Pith reviewed 2026-05-22 21:34 UTC · model grok-4.3

classification 🪐 quant-ph
keywords prepare-and-measurestochastic teleportationquantum communicationentanglementnonlocalitymulti-particle measurementsrandom access coding
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The pith

Stronger-than-quantum nonlocality allows exact stochastic teleportation of one qubit from N using only two bits of communication for any N.

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

The paper investigates prepare-and-measure scenarios in which entanglement helps transmit quantum information over channels with limited capacity. It formalizes the framework and supplies numerical optimization tools for such protocols. The key focus is a stochastic teleportation task where the sender possesses N qubits and the receiver must recover a chosen one on demand. The authors prove that two bits of classical communication are sufficient to solve this task exactly for every N when the parties can access stronger-than-quantum nonlocality. They further demonstrate that genuine multi-particle entangled measurements enable construction of a universal stochastic teleportation machine with fidelity that does not depend on the input state.

Core claim

By using genuine multi-particle entangled measurements, the sender and receiver can build a universal stochastic teleportation machine. This machine recovers any demanded qubit from the sender's collection of N qubits with perfect fidelity using only two bits of communication, and the performance remains the same regardless of which quantum input is chosen, provided stronger-than-quantum nonlocality is available.

What carries the argument

Genuine multi-particle entangled measurements that construct a universal stochastic teleportation machine with input-independent fidelity.

If this is right

  • Exact stochastic teleportation is achievable for arbitrary N with a fixed two-bit communication budget when stronger-than-quantum nonlocality is used.
  • Entanglement-based protocols for quantum communication tasks can be derived systematically from known primitives including teleportation, cloning machines, and random access coding.
  • The prepare-and-measure scenario with shared entanglement admits numerical optimization for a wide range of communication tasks.
  • Teleportation fidelity can be made independent of the specific quantum input through multi-particle measurements.

Where Pith is reading between the lines

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

  • Such constructions may help identify the communication advantages that require resources beyond standard quantum theory.
  • Connections to random access coding suggest broader applicability to other limited-communication quantum tasks.
  • Universal machines of this type could serve as benchmarks for testing the strength of nonlocality in experimental setups.

Load-bearing premise

That stronger-than-quantum nonlocality can be harnessed via genuine multi-particle entangled measurements to achieve exact performance without additional constraints on the channel.

What would settle it

A demonstration that quantum protocols in the prepare-and-measure scenario achieve fidelity strictly less than one for the stochastic teleportation task with N greater than two and only two bits of communication.

Figures

Figures reproduced from arXiv: 2504.00162 by Armin Tavakoli, Elna Svegborn, Jef Pauwels.

Figure 1
Figure 1. Figure 1: FIG. 1 [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2 [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3: (a) [PITH_FULL_IMAGE:figures/full_fig_p007_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: , show that for N = 3, a universal stochastic teleportation protocol exists that consumes a single ebit and achieves a state-independent fidelity of Findep = 3/4, which matches the corresponding optimal average fidelity. Moreover, we note that performance of the protocols increases with the local dimension of the entangled state, and that this improvement is more pronounced when the number of input qubits … view at source ↗
read the original abstract

We investigate prepare-and-measure scenarios in which a sender and a receiver use entanglement to send quantum information over a channel with limited capacity. We formalise this framework, identify its basic properties and provide numerical tools for optimising quantum protocols for generic communication tasks. The seminal protocol for sending quantum information over a classical channel is teleportation. We study a natural stochastic generalisation in which the sender holds $N$ qubits from which the receiver can recover one on demand. We show that with two bits of communication alone, this task can be solved exactly for all $N$, if the sender and receiver have access to stronger-than-quantum nonlocality. We then consider entanglement-based protocols and show that these can be constructed systematically by leveraging connections to several well-known quantum information primitives, such as teleportation, cloning machines and random access coding. In particular, we show that by using genuine multi-particle entangled measurements, one can construct a universal stochastic teleportation machine, i.e.~a device whose teleportation fidelity is independent of the quantum input.

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 paper formalizes prepare-and-measure scenarios augmented by entanglement for transmitting quantum information over classically limited channels. It develops numerical optimization tools for generic tasks and focuses on stochastic teleportation, in which a sender holds N qubits and the receiver must recover any one on demand. The central claims are that two bits of classical communication suffice for exact recovery for arbitrary N when stronger-than-quantum nonlocality is permitted, and that entanglement-based protocols can be constructed systematically by reduction to teleportation, cloning, and random-access coding; in particular, genuine multi-particle entangled measurements yield a universal stochastic teleportation machine whose fidelity is independent of the input state.

Significance. If the derivations hold, the work supplies a systematic route from established quantum primitives to new communication protocols and demonstrates that input-independent fidelity is achievable in the stochastic teleportation setting. The explicit linkage to cloning and random-access coding, together with the exact solutions under stronger nonlocality, constitutes a concrete advance in resource theories of quantum communication.

minor comments (2)
  1. §3 (numerical tools): the description of the semidefinite-programming relaxation for the prepare-and-measure optimization lacks an explicit statement of the relaxation order or the convergence criterion used to certify the reported exact solutions.
  2. Figure 2 (protocol diagram): the caption does not indicate whether the multi-particle measurement is performed on the sender’s N qubits plus the shared entangled state or on a different subset; this affects readability of the universal-machine construction.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive summary, significance assessment, and recommendation of minor revision. No major comments were raised in the report.

Circularity Check

0 steps flagged

No significant circularity

full rationale

The paper formalizes the prepare-and-measure scenario with shared entanglement, identifies basic properties, and provides numerical optimization tools. It derives stochastic teleportation protocols by explicit connections to independent primitives (teleportation, cloning, random access coding) and invokes stronger-than-quantum nonlocality as an external resource to achieve exactness for arbitrary N. No quoted step reduces a claimed prediction or uniqueness result to a fitted parameter, self-definition, or self-citation chain; the central constructions are presented as systematic derivations from the formalized framework without load-bearing self-reference.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Based solely on abstract; no free parameters, invented entities, or ad-hoc axioms identified beyond standard quantum information assumptions such as entanglement and nonlocality.

axioms (1)
  • standard math Standard quantum mechanics and prepare-and-measure scenario assumptions hold, including validity of entanglement and measurement primitives.
    Paper relies on teleportation, cloning, and random access coding as background.

pith-pipeline@v0.9.0 · 5713 in / 1257 out tokens · 35378 ms · 2026-05-22T21:34:36.958017+00:00 · methodology

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Reference graph

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