Pith. sign in

REVIEW 5 cited by

Quantum Fisher Information and the Curvature of Entanglement

Not yet reviewed by Pith; the record is open.

This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.

SPECIMEN: schema-true, not a live event

T0 review · schema-true

One-sentence machine reading of the paper's core claim.

pith:XXXXXXXX · record.json · timestamp

arxiv 2504.13729 v4 pith:DDSEJ5EV submitted 2025-04-18 quant-ph

classification quant-ph
keywords couplingquantumconcurrenceeigenstatesentanglementcasecurvaturederivative
verification ladder T0 review T1 audit T2 compute T3 formal
0 comments
read the original abstract

We explore the relationship between quantum Fisher information (QFI) and the negative of the second derivative of concurrence with respect to the coupling between two qubits, referred to as the curvature of entanglement (CoE). The two-qubit system serves as a minimal model to study the connection between QFI and dynamically generated entanglement in scenarios where the measured quantity is a two- or many-body coupling strength. We analyze in detail the pure-state lossless case for which general results can be inferred and we also consider a simple interaction Hamiltonian in the case of one form of loss applied to the qubits. For a two-qubit quantum probe used to estimate the coupling constant appearing in the interaction Hamiltonian we show, for certain initial conditions, that there are times such that CoE = QFI. These times can be associated with the concurrence, viewed as a function of the coupling parameter, being a maximum. We examine the time evolution of the concurrence of the eigenstates of the symmetric logarithmic derivative (SLD). Measurements using the SLD eigenstates as basis are optimal for saturating the quantum Cramer bound. We show that, for several families of initially separable and initially entangled states, the SLD eigenstates are simple product states when CoE = QFI.

Discussion (0). Continue with ORCID to comment.

Forward citations

Cited by 5 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Entanglement response to Temperature in Interacting Two-Qubit Thermal States

    quant-ph 2026-06 unverdicted novelty 6.0 of 10

    Exact expressions for thermal concurrence, its first and second derivatives, and bounds are derived establishing that thermal quantum Fisher information constrains the response and robustness of entanglement to temper...

  2. Information-Geometric Bound on the Robustness of Entanglement Generation

    quant-ph 2026-06 unverdicted novelty 6.0 of 10

    For two interacting qubits the reduction in concurrence from fluctuations in interaction strength is bounded by the quantum Fisher information with respect to that strength.

  3. Quantum Crossovers Revealed by Local Measurements

    quant-ph 2026-05 unverdicted novelty 6.0 of 10

    Local quantum Fisher information and Bloch vector behavior characterize quantum crossovers where global indicators like steering ellipsoid volume remain insensitive.

  4. Geometric Aspects of Entanglement Generating Hamiltonian Evolutions

    quant-ph 2026-01 conditional novelty 6.0 of 10

    Explicit optimal and suboptimal stationary Hamiltonians connecting separable two-qubit states to maximally entangled states differ systematically in efficiency, curvature, average path entanglement, and short-time non...

  5. Dynamical quantum phase transition with divergent multipartite entanglement

    quant-ph 2025-06 reject novelty 6.0 of 10

    In the quench dynamics of the transverse-field Ising chain, the quantum Fisher information density at a critical time grows logarithmically with system size, signaling a multipartite-entanglement-driven dynamical phas...

Pith tools