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Nonlocal Variable-Strength Measurements of N Qubits Using GHZ-like Entanglement
Quantum Physics · Submitted 28 Feb 2021
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim An explicit relation between the overall measurement strength and the meter entanglement as quantified by the $n$-tangle is derived, opening the door to a new interpretation of the $n$-tangle as a resource for nonlocal measurements.
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The abstract, sentence by sentence
The direct measurement of nonlocal properties of entangled quantum systems has been the subject of several recent experimental investigations. Of particular interest is the implementation of nonlocal measurements via indirect measurement schemes, which allow for greater flexibility in the control of the measurement strength. Building on previous results established in the bipartite case, we present a scheme to implement genuine nonlocal measurements of N-qubit systems with variable strength, using GHZ-like entangled qubit meters. This method can be applied to the joint measurement of commuting product observables, enabling us to distinguish between orthogonal nonlocal states, such as Bell states, with minimal disturbance and arbitrary resolution. An explicit relation between the overall measurement strength and the meter entanglement as quantified by the $n$-tangle is derived, opening the door to a new interpretation of the $n$-tangle as a resource for nonlocal measurements.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The direct measurement of nonlocal properties of entangled quantum systems has been the subject of several recent experimental investigations. | background 1.00 | 0.03 | 0.02 | asserted 1.00 |
| s1 | Of particular interest is the implementation of nonlocal measurements via indirect measurement schemes, which allow for greater flexibility in the control of the measurement strength. | background 1.00 | 0.06 | 0.04 | asserted 0.95 |
| s2 | Building on previous results established in the bipartite case, we present a scheme to implement genuine nonlocal measurements of N-qubit systems with variable strength, using GHZ-like entangled qubit meters. | contribution 0.99 | 0.92 | 0.37 | asserted 1.00 |
| s3 | This method can be applied to the joint measurement of commuting product observables, enabling us to distinguish between orthogonal nonlocal states, such as Bell states, with minimal disturbance and arbitrary resolution. | contribution 0.53 | 0.73 | 0.18 | asserted 0.73 |
| s4 | An explicit relation between the overall measurement strength and the meter entanglement as quantified by the $n$-tangle is derived, opening the door to a new interpretation of the $n$-tangle as a resource for nonlocal measurements. | result 0.70 | 0.93 | 0.47 | asserted 0.90 |
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Original abstract
The direct measurement of nonlocal properties of entangled quantum systems has been the subject of several recent experimental investigations. Of particular interest is the implementation of nonlocal measurements via indirect measurement schemes, which allow for greater flexibility in the control of the measurement strength. Building on previous results established in the bipartite case, we present a scheme to implement genuine nonlocal measurements of N-qubit systems with variable strength, using GHZ-like entangled qubit meters. This method can be applied to the joint measurement of commuting product observables, enabling us to distinguish between orthogonal nonlocal states, such as Bell states, with minimal disturbance and arbitrary resolution. An explicit relation between the overall measurement strength and the meter entanglement as quantified by the $n$-tangle is derived, opening the door to a new interpretation of the $n$-tangle as a resource for nonlocal measurements.
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What this paper does with the arXiv papers it cites
What it cites · 5 sentences without a confident label
Builds on 2 papers
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In this construction, the measurement strength is directly given by the square root of the tangle of the nonlocal meter state, a generalization of the result of [ref] which establishes the $n$-tangle as a resource for nonlocal generalized measurements.
Nonlocal Generalized Quantum Measurements of Spin Products Without Maximal Entanglement · Conclusions · 0.93
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Following previous works concerning bipartite qubit systems [ref] , we present here a novel scheme to measure multipartite nonlocal qubit systems with arbitrary measurement strength, and which is resource-efficient in terms of meter entanglement.
Complete and Deterministic Bell State Measurement Using Nonlocal Spin Products · Introduction · 0.98
Compares with 1 paper
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Comparing Eq. [ref] with Eq. [ref], it is apparent that the measurement protocol described here constitutes a minimally-disturbing implementation of a 2-outcome nonlocal VSM, with measurement strength $𝔰=cos2θ$ similar to the one in [ref] .
Nonlocal Generalized Quantum Measurements of Spin Products Without Maximal Entanglement · Two-outcome nonlocal VSM · 1.00
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