Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Chinese Physics B

Improved frequency standard via weighted graph states

Peng Xue

Published Oct 1, 2012• 6 citations
Publisher

Abstract

We study the spin squeezing property of weighted graph states, which can be used to improve sensitivity in interferometry. We study the time evolution of spin squeezing under local decoherence acting independently on each qubit. Based on the analysis, the spin squeezing of the weighted graph states is somehow robust in the presence of decoherence and the decoherence limit in the improvement of the interferometric sensitivity is still achievable. Furthermore, one can obtain the optimal improvement of sensitivity by tuning the weighted of each edges of the weighted graph state.

DOI
10.1088/1674-1056/21/10/100306

Related papers

Spin-squeezing property of weighted graph states

Peng Xue

We study the spin-squeezing property of weighted graph states, which can be used to improve the sensitivity in interferometry. Decoherence reduces the spin-squeezing property but the result remains superior over other reference schemes with Greenberger-Horne-Zeilinger (GHZ) type maximally entangled states and product states. We study the time evolution of spin squeezing of weighted graph states coupled to different decoherence channels. Based on the analysis, the spin squeezing of the weighted graph states is robust in the presence of decoherence, and the decoherence limit in the improvement of the interferometric sensitivity is still achievable.

arXiv:1204.6479•Physical Review A•Aug 7, 2012•9 citations

Weighted hypergraph states as a resource for quantum metrology

B. J. Alexander, M. S. Tame

Quantum correlations can be used to improve sensing precision beyond classical limits, yet the correlated resource states needed can be challenging to prepare and preserve. Here, we study the family of weighted hypergraph states and identify subclasses characterized by their underlying graph topology that exhibit enhanced metrological performance. Using the quantum Fisher information and a novel Dicke state basis representation, we show that these subclasses outperform both separable and standard weighted graph state benchmarks over broad ranges of edge weights corresponding to weak controlled operations between qubits representing the vertices of the graph. We provide analytical formulas for an arbitrary number $N$ of qubits, supplemented by a general study, while focusing a detailed analysis on the example case of $N=4$. By identifying the critical probabilities for local dephasing, we show that adding higher-order weighted hyperedges for $N$ qubits can enhance metrological robustness, allowing the resulting states to retain a quantum advantage at higher noise levels. These probe states exhibit favorable scaling, enhanced precision, and noise tolerance. Our findings establish weighted hypergraph states as viable, structurally tunable and robust resources for quantum-enhanced metrology.

quant-pharXiv:2610.42129•Nov 2, 2026

Spin squeezing and decoherence limit in Ramsey spectroscopy

Duger Ulam-Orgikh, Masahiro Kitagawa

It is known that a partially entangled state gives improved sensitivity in generalized Ramsey spectroscopy in the presence of decoherence, whereas a maximally entangled state does not. However, it has been an open question whether the known decoherence limit in the improvement is achievable. We show that every spin-squeezed state possesses pairwise entanglement, thereby improving the spectroscopic sensitivity, and that even suboptimal entanglement in its easiest implementation suffices to asymptotically reach the decoherence limit without any measurement optimization.

Physical Review A•Oct 8, 2001•130 citations

Weighted graph states as a resource for quantum metrology

B. J. Alexander, Ş. K. Özdemir, M. S. Tame

Quantum metrology exploits quantum mechanical effects to increase the precision of measurements of physical quantities. A wide variety of applications are currently being developed for scientific and technological purposes, however, most research relies on the use of highly entangled resource states that are challenging to generate and control in a given physical system. Here, we study the use of weighted graph states as more accessible resources for quantum metrology, which yield a favorable precision beyond the classical limit, approaching the Heisenberg limit. We find a notable robustness to variation in weights and less challenging weight requirements compared to standard graph states, which require a maximal weight at all edges. Both of these aspects reduce the practical demands in a physical setup, with the latter implying significantly less entanglement is required to gain a quantum advantage in metrology. We study the quantum Fisher information and optimized estimator variance of two identified sub classes of weighted graph states for an arbitrary number of N qubits, providing analytical forms and investigating their scaling. Our work opens up opportunities for using weakly entangled states in quantum-enhanced metrology.

quant-pharXiv:2602.13026•Feb 16, 2026•0 citations

Spin Squeezing and Decoherence Limit in Ramsey Spectroscopy

Duger Ulam-Orgikh, Masahiro Kitagawa

It is known that partially entangled state gives improved sensitivity of Ramsey spectroscopy in the presence of decoherence, whereas maximally entangled state gives no improvement. However it has been an open question whether the absolute limit in the improvement is attainable by optimal entanglement alone or via measurement optimization. In this Paper, we answer this question by showing that even sub-optimal entanglement generated by the simplest spin squeezing can asymptotically attain the absolute improvement with increasing number of atoms.

Kluwer Academic Publishers eBooks•Feb 24, 2006•2 citations

Spin Noise and Spin Relaxation in Spin Squeezed Alkali-Metal Vapors

Iannis K. Kominis

Spin noise sets fundamental limits to the precision of measurements using spin-polarized atomic vapors, such as performed with sensitive atomic magnetometers. Spin squeezing offers the possibility to extend the measurement precision beyond the standard quantum limit of uncorrelated atoms. Contrary to the current understanding, we show that even in the presence of spin relaxation, spin squeezing can lead to a significant reduction of spin noise, and hence an increase in magnetometric sensitivity, for a long measurement time. This is the case when correlated spin relaxation due to binary alkali-atom collisions dominates independently acting decoherence processes.

•Aug 2, 2007•0 citations
We study the spin squeezing property of weighted graph states, which can be used to improve sensitivity in interferometry. We study the time evolution of spin squeezing under local decoherence acting independently on each qubit. Based on the analysis, the spin squeezing of the weighted graph states is somehow robust in the presence of decoherence and the decoherence limit in the improvement of the interferometric sensitivity is still achievable. Furthermore, one can obtain the optimal improvement of sensitivity by tuning the weighted of each edges of the weighted graph state.
We study the spin-squeezing property of weighted graph states, which can be used to improve the sensitivity in interferometry. Decoherence reduces the spin-squeezing property but the result remains superior over other reference schemes with Greenberger-Horne-Zeilinger (GHZ) type maximally entangled states and product states. We study the time evolution of spin squeezing of weighted graph states coupled to different decoherence channels. Based on the analysis, the spin squeezing of the weighted graph states is robust in the presence of decoherence, and the decoherence limit in the improvement of the interferometric sensitivity is still achievable.
Quantum correlations can be used to improve sensing precision beyond classical limits, yet the correlated resource states needed can be challenging to prepare and preserve. Here, we study the family of weighted hypergraph states and identify subclasses characterized by their underlying graph topology that exhibit enhanced metrological performance. Using the quantum Fisher information and a novel Dicke state basis representation, we show that these subclasses outperform both separable and standard weighted graph state benchmarks over broad ranges of edge weights corresponding to weak controlled operations between qubits representing the vertices of the graph. We provide analytical formulas for an arbitrary number NNN of qubits, supplemented by a general study, while focusing a detailed analysis on the example case of N=4N=4N=4. By identifying the critical probabilities for local dephasing, we show that adding higher-order weighted hyperedges for NNN qubits can enhance metrological robustness, allowing the resulting states to retain a quantum advantage at higher noise levels. These probe states exhibit favorable scaling, enhanced precision, and noise tolerance. Our findings establish weighted hypergraph states as viable, structurally tunable and robust resources for quantum-enhanced metrology.
It is known that a partially entangled state gives improved sensitivity in generalized Ramsey spectroscopy in the presence of decoherence, whereas a maximally entangled state does not. However, it has been an open question whether the known decoherence limit in the improvement is achievable. We show that every spin-squeezed state possesses pairwise entanglement, thereby improving the spectroscopic sensitivity, and that even suboptimal entanglement in its easiest implementation suffices to asymptotically reach the decoherence limit without any measurement optimization.
Quantum metrology exploits quantum mechanical effects to increase the precision of measurements of physical quantities. A wide variety of applications are currently being developed for scientific and technological purposes, however, most research relies on the use of highly entangled resource states that are challenging to generate and control in a given physical system. Here, we study the use of weighted graph states as more accessible resources for quantum metrology, which yield a favorable precision beyond the classical limit, approaching the Heisenberg limit. We find a notable robustness to variation in weights and less challenging weight requirements compared to standard graph states, which require a maximal weight at all edges. Both of these aspects reduce the practical demands in a physical setup, with the latter implying significantly less entanglement is required to gain a quantum advantage in metrology. We study the quantum Fisher information and optimized estimator variance of two identified sub classes of weighted graph states for an arbitrary number of N qubits, providing analytical forms and investigating their scaling. Our work opens up opportunities for using weakly entangled states in quantum-enhanced metrology.
It is known that partially entangled state gives improved sensitivity of Ramsey spectroscopy in the presence of decoherence, whereas maximally entangled state gives no improvement. However it has been an open question whether the absolute limit in the improvement is attainable by optimal entanglement alone or via measurement optimization. In this Paper, we answer this question by showing that even sub-optimal entanglement generated by the simplest spin squeezing can asymptotically attain the absolute improvement with increasing number of atoms.
Spin noise sets fundamental limits to the precision of measurements using spin-polarized atomic vapors, such as performed with sensitive atomic magnetometers. Spin squeezing offers the possibility to extend the measurement precision beyond the standard quantum limit of uncorrelated atoms. Contrary to the current understanding, we show that even in the presence of spin relaxation, spin squeezing can lead to a significant reduction of spin noise, and hence an increase in magnetometric sensitivity, for a long measurement time. This is the case when correlated spin relaxation due to binary alkali-atom collisions dominates independently acting decoherence processes.