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

arXiv:1912.02418 · Physical Review A

Supersensitive quantum sensor based on criticality in an antiferromagnetic spinor condensate

Safoura Sadat Mirkhalaf, Emilia Witkowska, Luca Lepori

Published Apr 14, 2020• 33 citations
arXivHTMLPDF

Abstract

We consider an antiferromagnetic Bose-Einstein condensate in a transverse magnetic field with a fixed macroscopic magnetization. The system exhibits two different critical behaviors corresponding to transitions from polar to broken-axisymmetry and from antiferromagnetic to broken-axisymmetry phases, depending on the value of the magnetization. We exploit both types of system criticality as a resource in the precise estimation of the control parameter value. We quantify the achievable precision by the quantum Fisher information. We demonstrate supersensitivity and show that the precision scales with the number of atoms up to ${N}^{4}$ around criticality. In addition, we study the precision based on the error-propagation formula, which provides a simple-to-measure signal whose scaling coincides with the quantum Fisher information. Finally, we take into account the effect of nonzero temperature and show that sub-shot-noise sensitivity in the estimation of the control parameter is achievable in the low-temperature limit.

DOI
10.1103/physreva.101.043609

Related papers

Criticality-enhanced quantum sensing in ferromagnetic Bose-Einstein condensates: Role of readout measurement and detection noise

Safoura Sadat Mirkhalaf, Daniel Benedicto Orenes, Morgan W. Mitchell +1 more

We theoretically investigate estimation of the control parameter in a ferromagnetic Bose-Einstein condensate near second-order quantum phase transitions. We quantify sensitivity by quantum and classical Fisher information and use the error-propagation formula. For these different metrics, we find the same beyond standard quantum limit (SQL) scaling with atom number near critical points and SQL scaling away from critical points. We find that both depletion of the ${m}_{f}=0$ Zeeman sublevel and transverse magnetization provide signals of sufficient quality to saturate the sensitivity scaling. To explore the effect of experimental imperfections, we study the scaling around criticality at nonzero temperature and with nonzero detection noise. Our results suggest the feasibility of sub-SQL sensing in ferromagnetic condensates with current experimental capabilities.

arXiv:2010.13133•Physical Review A•Feb 16, 2021•33 citations

Interferometric sensitivity and entanglement by scanning through quantum phase transitions in spinor Bose-Einstein condensates

Polina Feldmann, Manuel Gessner, Marco Gabbrielli +4 more

Recent experiments demonstrated the generation of entanglement by quasiadiabatically driving through quantum phase transitions of a ferromagnetic spin-1 Bose-Einstein condensate in the presence of a tunable quadratic Zeeman shift. We analyze, in terms of the Fisher information, the interferometric value of the entanglement accessible by this approach. In addition to the Twin-Fock phase studied experimentally, we unveil a second regime, in the broken axisymmetry phase, which provides Heisenberg scaling of the quantum Fisher information and can be reached on shorter time scales. We identify optimal unitary transformations and an experimentally feasible optimal measurement prescription that maximize the interferometric sensitivity. We further ascertain that the Fisher information is robust with respect to nonadiabaticity and measurement noise. Finally, we show that the quasiadiabatic entanglement preparation schemes admit higher sensitivities than dynamical methods based on fast quenches.

arXiv:1712.03896•Physical Review A•Mar 27, 2018•29 citations

Quantum sensing of supersensitivity for the Ohmic quantum reservoir

Qing-Shou Tan, Wei Wu, Lan Xu +2 more

We propose an approach to implement a supersensitive estimation of the key parameters of the Ohmic-family spectral density with coherent spin states as the quantum sensor. This method can dramatically improve the estimation precision of the reservoir coupling strength as well as the cutoff frequency of the spectral density, by using both the number of spins $N$ and encoding time $t$ as effective resources. The quantum Fisher information indicates that the estimation sensitivity of the spectral density can surpass the shot-noise limit for all the sub-Ohmic, Ohmic, and super-Ohmic reservoirs. In particular, for super-Ohmic reservoirs, the precision can achieve a scaling $\ensuremath{\propto}1/(Nt)$. We also present the measurement scheme which can saturate the quantum Cram\'er-Rao bound.

Physical Review A•Sep 2, 2022•18 citations

Critical quantum thermometry and its feasibility in spin systems

Enes Aybar, Artur Niezgoda, Safoura Sadat Mirkhalaf +3 more

In this work, we study temperature sensing with finite-sized strongly correlated systems exhibiting quantum phase transitions. We use the quantum Fisher information (QFI) approach to quantify the sensitivity in the temperature estimation, and apply a finite-size scaling framework to link this sensitivity to critical exponents of the system around critical points. We numerically calculate the QFI around the critical points for two experimentally-realizable systems: the spin-1 Bose-Einstein condensate and the spin-chain Heisenberg XX model in the presence of an external magnetic field. Our results confirm finite-size scaling properties of the QFI. Furthermore, we discuss experimentally-accessible observables that (nearly) saturate the QFI at the critical points for these two systems.

arXiv:2204.02734•Quantum•Sep 19, 2022•21 citations

Using the ground state of an antiferromagnetic spin-1 atomic condensate for Heisenberg-limited metrology

Ling-Na Wu, Li You

We show that the ground state of a spin-1 atomic condensate with antiferromagnetic interactions constitutes a useful resource for quantum metrology upon approaching the Heisenberg limit. Unlike a ferromagnetic condensate state where individual atomic spins are aligned in the same direction, the antiferromagnetic ground-state condensate is a condensate of spin-singlet atom pairs. The inherent correlation between paired atoms allows for parameter estimation at precisions beyond the standard quantum limit (SQL) for uncorrelated atoms. The degree of improvement over the SQL is measured by the scaled quantum Fisher information (QFI), whose dependence on the ratio of linear Zeeman shift $p$ to spin-dependent atomic interaction $c$ is studied. At a typical value of $p=0.4c$, which corresponds to a magnetic field of $28.6\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{G}$ for $c=50\mathrm{h}$ Hz (for $^{23}\mathrm{Na}$ atom condensate in the $F=1$ state at a typical density of $\ensuremath{\sim}{10}^{14}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$), the scaled QFI can reach $\ensuremath{\sim}0.48N$, which approaches the limit of $0.5N$ for the twin-Fock state ${|N/2\ensuremath{\rangle}}_{+}{|N/2\ensuremath{\rangle}}_{\ensuremath{-}}$. Our work encourages experimental efforts to reach the ground state of an antiferromagnetic condensate at a extremely low magnetic field.

Physical Review A•Mar 3, 2016•11 citations

Fisher-information manifestation of dynamical stability and transition to self-trapping for Bose-Einstein condensates

Yixiao Huang, Wei Zhong, Zhe Sun +1 more

Quantum Fisher information, which plays a central role in parameter estimation theory, is a useful quantity for metrological applications. We use quantum Fisher information to distinguish and characterize behaviors of the evolved state for Bose-Einstein condensates in a symmetric double well, which display a classical bifurcation and a transition from Josephson oscillation to self-trapping. We find that the precision of the parameter estimation on the evolved state in the unstable regime is much higher than that in the stable regime, which lies at the shot-noise level. We also show that the parameter sensitivity of the evolved state approaches the Heisenberg limit in the Josephson oscillation regime, while it is just scaled as the shot-noise limit in the self-trapping regime. Finally, we discuss the relation between the parameter sensitivity of the evolved state and the entanglement entropy.

arXiv:1204.2064•Physical Review A•Jul 18, 2012•18 citations
We consider an antiferromagnetic Bose-Einstein condensate in a transverse magnetic field with a fixed macroscopic magnetization. The system exhibits two different critical behaviors corresponding to transitions from polar to broken-axisymmetry and from antiferromagnetic to broken-axisymmetry phases, depending on the value of the magnetization. We exploit both types of system criticality as a resource in the precise estimation of the control parameter value. We quantify the achievable precision by the quantum Fisher information. We demonstrate supersensitivity and show that the precision scales with the number of atoms up to N4{N}^{4}N4 around criticality. In addition, we study the precision based on the error-propagation formula, which provides a simple-to-measure signal whose scaling coincides with the quantum Fisher information. Finally, we take into account the effect of nonzero temperature and show that sub-shot-noise sensitivity in the estimation of the control parameter is achievable in the low-temperature limit.
We theoretically investigate estimation of the control parameter in a ferromagnetic Bose-Einstein condensate near second-order quantum phase transitions. We quantify sensitivity by quantum and classical Fisher information and use the error-propagation formula. For these different metrics, we find the same beyond standard quantum limit (SQL) scaling with atom number near critical points and SQL scaling away from critical points. We find that both depletion of the mf=0{m}_{f}=0mf​=0 Zeeman sublevel and transverse magnetization provide signals of sufficient quality to saturate the sensitivity scaling. To explore the effect of experimental imperfections, we study the scaling around criticality at nonzero temperature and with nonzero detection noise. Our results suggest the feasibility of sub-SQL sensing in ferromagnetic condensates with current experimental capabilities.
Recent experiments demonstrated the generation of entanglement by quasiadiabatically driving through quantum phase transitions of a ferromagnetic spin-1 Bose-Einstein condensate in the presence of a tunable quadratic Zeeman shift. We analyze, in terms of the Fisher information, the interferometric value of the entanglement accessible by this approach. In addition to the Twin-Fock phase studied experimentally, we unveil a second regime, in the broken axisymmetry phase, which provides Heisenberg scaling of the quantum Fisher information and can be reached on shorter time scales. We identify optimal unitary transformations and an experimentally feasible optimal measurement prescription that maximize the interferometric sensitivity. We further ascertain that the Fisher information is robust with respect to nonadiabaticity and measurement noise. Finally, we show that the quasiadiabatic entanglement preparation schemes admit higher sensitivities than dynamical methods based on fast quenches.
We propose an approach to implement a supersensitive estimation of the key parameters of the Ohmic-family spectral density with coherent spin states as the quantum sensor. This method can dramatically improve the estimation precision of the reservoir coupling strength as well as the cutoff frequency of the spectral density, by using both the number of spins NNN and encoding time ttt as effective resources. The quantum Fisher information indicates that the estimation sensitivity of the spectral density can surpass the shot-noise limit for all the sub-Ohmic, Ohmic, and super-Ohmic reservoirs. In particular, for super-Ohmic reservoirs, the precision can achieve a scaling $\ensuremath{\propto}1/(Nt)$. We also present the measurement scheme which can saturate the quantum Cram\'er-Rao bound.
In this work, we study temperature sensing with finite-sized strongly correlated systems exhibiting quantum phase transitions. We use the quantum Fisher information (QFI) approach to quantify the sensitivity in the temperature estimation, and apply a finite-size scaling framework to link this sensitivity to critical exponents of the system around critical points. We numerically calculate the QFI around the critical points for two experimentally-realizable systems: the spin-1 Bose-Einstein condensate and the spin-chain Heisenberg XX model in the presence of an external magnetic field. Our results confirm finite-size scaling properties of the QFI. Furthermore, we discuss experimentally-accessible observables that (nearly) saturate the QFI at the critical points for these two systems.
We show that the ground state of a spin-1 atomic condensate with antiferromagnetic interactions constitutes a useful resource for quantum metrology upon approaching the Heisenberg limit. Unlike a ferromagnetic condensate state where individual atomic spins are aligned in the same direction, the antiferromagnetic ground-state condensate is a condensate of spin-singlet atom pairs. The inherent correlation between paired atoms allows for parameter estimation at precisions beyond the standard quantum limit (SQL) for uncorrelated atoms. The degree of improvement over the SQL is measured by the scaled quantum Fisher information (QFI), whose dependence on the ratio of linear Zeeman shift ppp to spin-dependent atomic interaction ccc is studied. At a typical value of p=0.4cp=0.4cp=0.4c, which corresponds to a magnetic field of $28.6\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{G}$ for c=50hc=50\mathrm{h}c=50h Hz (for 23Na^{23}\mathrm{Na}23Na atom condensate in the F=1F=1F=1 state at a typical density of $\ensuremath{\sim}{10}^{14}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$), the scaled QFI can reach $\ensuremath{\sim}0.48N$, which approaches the limit of 0.5N0.5N0.5N for the twin-Fock state ${|N/2\ensuremath{\rangle}}_{+}{|N/2\ensuremath{\rangle}}_{\ensuremath{-}}$. Our work encourages experimental efforts to reach the ground state of an antiferromagnetic condensate at a extremely low magnetic field.
Quantum Fisher information, which plays a central role in parameter estimation theory, is a useful quantity for metrological applications. We use quantum Fisher information to distinguish and characterize behaviors of the evolved state for Bose-Einstein condensates in a symmetric double well, which display a classical bifurcation and a transition from Josephson oscillation to self-trapping. We find that the precision of the parameter estimation on the evolved state in the unstable regime is much higher than that in the stable regime, which lies at the shot-noise level. We also show that the parameter sensitivity of the evolved state approaches the Heisenberg limit in the Josephson oscillation regime, while it is just scaled as the shot-noise limit in the self-trapping regime. Finally, we discuss the relation between the parameter sensitivity of the evolved state and the entanglement entropy.