Metrologically useful states of spin-1 Bose condensates with macroscopic magnetization

Kajtoch, Dariusz; Pawłowski, Krzysztof; Witkowska, Emilia

doi:10.1103/physreva.97.023616

Cited by 9 publications

(26 citation statements)

References 45 publications

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“…Furthermore, in the large-T limit, takingρ T ∝ 1, we obtain that the QFI saturates a finite constant value, F Q [ρ T ,Ô] ∝ n∈H ψ n |Ô 2 |ψ n . In other words, we may have, in this case, that multipartite entanglement increases with temperature and remains large even at high temperature, as recently noticed in a spin-1 system [76].…”

Section: Thermalization In a Subspace Of The Full Hamiltoniansupporting

confidence: 64%

Multipartite Entanglement at Finite Temperature

Gabbrielli¹,

Smerzi²,

Pezzé³

2018

Sci Rep

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The interplay of quantum and thermal fluctuations in the vicinity of a quantum critical point characterizes the physics of strongly correlated systems. Here we investigate this interplay from a quantum information perspective presenting the universal phase diagram of the quantum Fisher information at a quantum phase transition. Different regions in the diagram are identified by characteristic scaling laws of the quantum Fisher information with respect to temperature. This feature has immediate consequences on the thermal robustness of quantum coherence and multipartite entanglement. We support the theoretical predictions with the analysis of paradigmatic spin systems showing symmetry-breaking quantum phase transitions and free-fermion models characterized by topological phases. In particular we show that topological systems are characterized by the survival of large multipartite entanglement, reaching the Heisenberg limit at finite temperature.

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Section: Thermalization In a Subspace Of The Full Hamiltoniansupporting

confidence: 64%

Multipartite Entanglement at Finite Temperature

Gabbrielli¹,

Smerzi²,

Pezzé³

2018

Sci Rep

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“…Matrices Γ ± share the same eigenvalues, but they have different eigenvectors 4 . Due to the rotational symmetry we have Γ 33 =Γ 11 , Γ 44 =Γ 22 , Γ 66 =Γ 55 and Γ 34 =−Γ 12 [9].…”

Section: Identification Of the Best Interferometeric Configurationsmentioning

confidence: 99%

“…We believe that such analysis would help in understanding very foundations of quantum interferometry using spin-1 atomic condensates and further planning of experiments. In what follows, we consider the most general form of linear quantum interferometry [9]. We identify optimal configurations of interferometric rotations by studying the quantum Fisher information (QFI) for the initial polar state.…”

Section: Introductionmentioning

confidence: 99%

Optimal quantum interferometry robust to detection noise using spin-1 atomic condensates

et al. 2019

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Implementation of the quantum interferometry concept to spin-1 atomic Bose-Einstein condensates is analyzed by employing a polar state evolved in time. In order to identify the best interferometric configurations, the quantum Fisher information (QFI) is maximized. Three optimal configurations are identified, among which one was not reported in the literature yet, although it gives the highest value of the QFI in experimentally achievable short time dynamics. Details of the most optimal configurations are investigated based on the error-propagation formula which includes the interaction-based readout protocol to reduce the destructive effect of detection noise. In order to obtain Heisenberg scaling accessible by present day experimental techniques, an efficient measurement and a method for the inversion of dynamics were developed, as necessary for the protocol's implementation. A Niezgoda et al ( ) where D N J J N J J J N J , , 0 2 1 1 2 , 5 N J J 0 2 ( ) H J J J N J J J J H J 8 New J. Phys. 21 (2019) 093037 A Niezgoda et al J J J J 4 2 , 4 2 I z z z z L =ˆ, was already realized experimentally [15] and the measurement of J z 2 was performed. Here, we just demonstrate the origin and rightness of such a choice pointing out its sensitivity to the detection noise. Indeed, one can show numerically that J J J J 4 2 44 II z † † J g g a a , 4 9 z l l l , 0 0 = -ˆˆˆˆ( ) † † which are symmetric when l=S and anti-symmetric for l=A. The above spin operators have cyclic commutation relations, e.g. J J J , 2 i x l y l z l , , , = [ˆˆ]ˆ. The Hamiltonian that we used in the previous subsections expressed in terms of the symmetric and anti-symmetric operators reads: c J J J . 5 0 in which the coefficient D 0 (N, J, 0) has a closed form expression D N J J N J J J N J J N J , , 0 2 1 1 2 e 2 1 . B . 9 N J J 0 2 1 J J N 1 4 † † † a a J J J a J J A a 0 1 2 1 1 2 0 1 2 0 . C.11 J J J

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“…Collisions between the different internal states of the atoms allow spin-changing collisions that have been studied in detail in [7][8][9][10]. These collisions can notably be employed to generate spin squeezing [11][12][13], that can be used to overcome the quantum shot noise limit [14][15][16][17][18]. Spinor dynamics was also studied in two dimensional systems [15], and in the presence of periodic potentials and across the superfluid to Mott insulator transition [19].…”

Section: Introductionmentioning

confidence: 99%

Exploring the thermodynamics of spin-1 Bose gases with synthetic magnetization

et al. 2019

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We study the thermodynamic properties of a spin-1 Bose gas across the Bose-Einstein condensation transition. We present the theoretical description of the thermodynamics of a trapped ideal spin-1 Bose gas and we describe the phases that can be obtained in this system as a function of the temperature and of the populations in the different spin components. We propose a simple way to realize a 'synthetic magnetization' that can be used to probe the entire phase diagram while keeping the real magnetization of the system fixed. We experimentally demonstrate the use of such method to explore different phases in a sample with zero total magnetization. Our work opens up new perspectives to study isothermal quenching dynamics through different magnetic phases in spinor condensates.

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Metrologically useful states of spin-1 Bose condensates with macroscopic magnetization

Cited by 9 publications

References 45 publications

Multipartite Entanglement at Finite Temperature

Multipartite Entanglement at Finite Temperature

Optimal quantum interferometry robust to detection noise using spin-1 atomic condensates

Exploring the thermodynamics of spin-1 Bose gases with synthetic magnetization

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