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arXiv:2604.20149 · Physics Letters A

Average metric adjusted skew information of coherence under conical 2-designs generalized equiangular measurements

Baolong Cheng, Linlin Ye, Zhaoqi Wu

quant-phSubmitted Apr 22, 2026• Announced Apr 23, 2026• 0 citations• Revised Oct 2, 2026 (v2)
v1 · Apr 22, 2026v2 · Oct 2, 2026
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Abstract

Quantum coherence is an important quantum resource which plays a pivotal role in the field of quantum information. Based on metric adjusted skew information, we define a measure of quantum uncertainty to study average coherence under conical 2-designs generalized equiangular measurements, and prove the equivalence of this measure to the scaled average coherence based on metric adjusted skew information under a set of unitary groups, operator orthonormal bases, and mutually unbiased bases. We also derive two trade-off relations by this measure and solve a conjecture. Furthermore, we give two entanglement criteria by this measure and conical 2-designs generalized equiangular measurement, respectively, and illustrate the effectiveness of them by explicit examples.

Journal reference
Phys. Lett. A 2026, 595: 132087
DOI
10.1016/j.physleta.2026.132087
Comments
21 pages,1 figure

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Abstract Quantum coherence is one of the characteristic features of quantum mechanics and underpins many quantum mysteries. In this work, we investigate the average coherence of a quantum state with respect to symmetric positive operator-valued measures using metric-adjusted skew information. Specifically, we derive explicit expressions for the average coherence relative to mutually unbiased measurements and to general symmetric informationally complete measurements, and establish a complementary relation between average coherence and maximal coherence. Furthermore, we introduce a measure of average coherence based on metric-adjusted skew information for states with respect to a generalized symmetric measurements (GSMs). When these GSMs are required to be equinumerous, the corresponding average coherence reduces to that for symmetric measurements. Finally, we evaluate and compare various average coherence measures with different operator monotone functions for qubit states, Werner states, and isotropic states.
Abstract Quantum measurements are important tools in quantum information, represented by positive, operator-valued measures. A wide class of symmetric measurements is given via generalized equiangular measurements (GEAMs) that form conical 2-designs. We show that only two positive constants are needed to fully characterize a variety of important quantum measures constructed from such operators. Examples are given for entropic uncertainty relations, the Brukner–Zeilinger invariants, quantum coherence, quantum concurrence, and the Schmidt-number criterion for entanglement detection. Our results indicate that similar relations may also hold for conical 2-designs from beyond the class of GEAMs.
We investigate quantum average correlations and complementarity relations based on metric-adjusted skew information. Several natural averaging procedures are considered, including complete families of mutually unbiased bases, all orthonormal bases, operator orthonormal bases, and twirling channels induced by the unitary group. All these approaches lead to the same closed expression, which identifies the resulting average correlation as an intrinsic quantity independent of the averaging scheme. By defining measures of wave and particle features via metric-adjusted skew information, we establish complementarity relations among wave and particle features, quantum entropy, and average correlation. These results provide a unified framework for investigating quantum average correlations and complementarity relations in terms of metric-adjusted skew information.
Abstract The quantum uncertainty relation characterizes the restriction of the quantum coherence on different measurement bases. The skew information of coherence is a coherence measure both operationally and informatically. We study the quantum uncertainty relation for the skew information of coherence under any two orthonormal bases. In qubit and qutrit systems, we derive the quantum uncertainty relations with the lower bounds in the factorized forms by the purity of quantum states and the incompatibility between two orthonormal bases. Especially the lower bound in qubit systems is strictly positive for non-maximally mixed states and incompatible orthonormal bases. These quantum uncertainty relations reveal the intrinsic relation among the coherence, the purity and the incompatibility between two orthonormal bases quantitatively. The advantages of these quantum uncertainty relations are illustrated by some specific examples. This method we developed here is beneficial to some other quantum uncertainty relations.