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arxiv: 2506.21988 · v2 · submitted 2025-06-27 · 🪐 quant-ph · cs.CR

Unifying communication paradigms in measurement-based delegated quantum computing

Fabian Wiesner , Jens Eisert , Anna Pappa This is my paper

Pith reviewed 2026-05-19 08:20 UTC · model grok-4.3

classification 🪐 quant-ph cs.CR
keywords delegated quantum computingmeasurement-based quantum computationblind quantum computationprepare-and-sendreceive-and-measurequantum cryptographyresource states
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The pith

Delegated quantum computing protocols can be translated between prepare-and-send and receive-and-measure settings by implementing missing components in each.

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

The paper establishes that the two primary ways of distributing preparation, entanglement, and measurement tasks between client and server in measurement-based delegated quantum computing are interconvertible. By realizing the key elements of existing protocols in the setting where they were previously absent, the work shows how to construct new protocols that operate in both settings at once and how to move protocols from one setting to the other. A sympathetic reader would care because this removes the need to treat the two communication paradigms as fundamentally separate, each locked into its own cryptographic and hardware constraints.

Core claim

By implementing the key components of most DQC protocols in the respective missing setting, we provide a method to build prospective protocols in both settings simultaneously and to translate existing protocols from one setting into the other.

What carries the argument

Cross-implementation of protocol components (qubit preparation, resource-state entanglement, and measurement) that were originally developed for only one of the two communication settings.

If this is right

  • New protocols can be designed from the outset to function in both prepare-and-send and receive-and-measure regimes.
  • Existing protocols written for one setting can be systematically rewritten for the other.
  • Setting-dependent theoretical constraints are shown to be avoidable rather than inevitable.

Where Pith is reading between the lines

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

  • The translation method could allow hardware teams to pick whichever setting is easier to implement on their particular devices.
  • Hybrid protocols that switch communication direction partway through a computation become conceivable.
  • The same cross-implementation approach might extend to other quantum communication tasks that currently treat preparation and measurement roles asymmetrically.

Load-bearing premise

That the key components of existing protocols can be realized in the alternate setting without introducing new cryptographic or experimental constraints that would invalidate the original security or blindness guarantees.

What would settle it

A concrete demonstration that at least one standard component, such as a particular entangled resource state or measurement pattern, cannot be moved to the other setting while preserving the original blindness property.

Figures

Figures reproduced from arXiv: 2506.21988 by Anna Pappa, Fabian Wiesner, Jens Eisert.

Figure 1
Figure 1. Figure 1: Visualization of the secure construction with I ={A,B,C,D} and H={A,B}. One shows security by proving the above definition for all sets of honest parties H⊆ I that are relevant for the security of the desired functionality. For example in QKD, it does not make sense to consider any of the two communicating parties to be dishonest; we are interested in proving a) correctness, where both the communicating pa… view at source ↗
Figure 2
Figure 2. Figure 2: Visualization of S blind . ℓ |ψC | is the size of the register for the client’s input ψC , E is a completely positive trace-preserving (CPTP) map to the space of linear operators on C ℓ |ψC | , ψS is a register of the server and c denotes the server’s behavior. If the server is honest, we assume a filter ♯S which inputs c= 0, ignores the received dimensionality of the client’s state and inputs any CPTP map… view at source ↗
Figure 3
Figure 3. Figure 3: Visualization of S ver . ℓ |ψC | is the size of the register for the client’s input ψC . |⊥⟩⟨⊥| is orthogonal to the space of possible honest outputs. If the server is honest, we assume a filter ♭S which inputs c= 0 and ignores the received dimensionality of the client’s state. The first type of implementation of S ver uses a composition of many instances of S blind, where some of them are used as traps to… view at source ↗
read the original abstract

Delegated quantum computing (DQC) allows clients with low quantum capabilities to outsource computations to a server hosting a quantum computer. This process is often envisioned within the measurement-based quantum computing framework, as it naturally facilitates blindness of inputs and computation. Hence, the overall process of setting up and conducting the computation encompasses a sequence of three stages: preparing the qubits, entangling the qubits to obtain the resource state, and measuring the qubits to run the computation. There are two primary approaches to distributing these stages between the client and the server that impose different constraints on cryptographic techniques and experimental implementations. In the prepare-and-send setting, the client prepares the qubits and sends them to the server, while in the receive-and-measure setting, the client receives the qubits from the server and measures them. Although these settings have been extensively studied independently, their interrelation and whether setting-dependent theoretical constraints are inevitable remain unclear. By implementing the key components of most DQC protocols in the respective missing setting, we provide a method to build prospective protocols in both settings simultaneously and to translate existing protocols from one setting into the other.

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 claims that the prepare-and-send and receive-and-measure settings in measurement-based delegated quantum computing can be unified by reassigning the key components (qubit preparation, resource-state entanglement, and measurement) between client and server, thereby enabling simultaneous construction of protocols in both settings and translation of existing protocols from one setting to the other while preserving security properties such as blindness.

Significance. If the translations rigorously preserve cryptographic guarantees, the work would offer a systematic bridge between two previously separate paradigms, allowing protocol designers to adapt constructions across experimental constraints without separate security analyses; this could streamline development of practical DQC schemes.

major comments (2)
  1. [Abstract and main construction (around the unification method)] The central claim that translations preserve blindness and verifiability rests on an unproven invariance of the cryptographic reduction under setting swap. No section derives that the simulator for the client's input in the new view remains computationally indistinguishable from the ideal functionality under the original hardness assumptions; the reduction is only sketched at the level of the abstract resource state.
  2. [Sections describing explicit translations of existing protocols] For the representative protocols whose key components are implemented in the alternate setting, the manuscript does not provide a full security analysis showing that no new cryptographic or experimental constraints invalidate the original guarantees; this is load-bearing for the translation claim.
minor comments (2)
  1. [Introduction] A diagram contrasting the stage distribution (preparation, entanglement, measurement) in both settings would improve clarity of the unification method.
  2. [Throughout the manuscript] Notation for resource states and client-server interfaces should be standardized across sections to avoid ambiguity when describing the reassignments.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their thorough review and valuable feedback on our manuscript. We address each major comment below and outline the revisions we will make to strengthen the security arguments.

read point-by-point responses

  1. Referee: [Abstract and main construction (around the unification method)] The central claim that translations preserve blindness and verifiability rests on an unproven invariance of the cryptographic reduction under setting swap. No section derives that the simulator for the client's input in the new view remains computationally indistinguishable from the ideal functionality under the original hardness assumptions; the reduction is only sketched at the level of the abstract resource state.

    Authors: We agree that the current presentation of security preservation under the setting swap is at a high level. The manuscript sketches the invariance at the abstract resource state but does not contain an explicit derivation of the simulator's indistinguishability in the swapped view. In the revised version we will add a dedicated subsection that constructs the simulator for the swapped setting and proves computational indistinguishability from the ideal functionality under the original hardness assumptions. revision: yes

  2. Referee: [Sections describing explicit translations of existing protocols] For the representative protocols whose key components are implemented in the alternate setting, the manuscript does not provide a full security analysis showing that no new cryptographic or experimental constraints invalidate the original guarantees; this is load-bearing for the translation claim.

    Authors: The manuscript illustrates the general translation method with representative protocols but does not supply complete security analyses for the translated instances. We acknowledge that verifying the absence of new constraints is necessary for the claim. In the revision we will expand the relevant sections to include full security analyses for the representative protocols in each translation direction, confirming that the original hardness assumptions continue to hold and that no additional experimental constraints are introduced. revision: yes

Circularity Check

0 steps flagged

No significant circularity; constructive translation method is self-contained

full rationale

The paper presents a constructive approach to implementing key components of DQC protocols (qubit preparation, entanglement, measurement) in the alternate communication setting to enable translation between prepare-and-send and receive-and-measure paradigms. No steps reduce by definition to their inputs, no fitted parameters are relabeled as predictions, and no load-bearing claims rest on self-citations that themselves require the target result. The derivation relies on explicit protocol translations rather than self-referential assumptions, remaining independent of the paper's own fitted values or prior unverified results.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The work rests on standard quantum information assumptions rather than new fitted parameters or invented entities.

axioms (1)
  • standard math Validity of the measurement-based quantum computing model and standard cryptographic assumptions for delegated quantum computing.
    The paper builds directly on established MBQC and DQC frameworks without stating new axioms.

pith-pipeline@v0.9.0 · 5719 in / 1079 out tokens · 26868 ms · 2026-05-19T08:20:23.759971+00:00 · methodology

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Reference graph

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