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The geometrical arrangement of a set of quantum states can be completely characterized using relational information only. This information is encoded in the pairwise state overlaps, as well as in Bargmann invariants of higher degree written…

Quantum Physics · Physics 2021-09-22 Michał Oszmaniec , Daniel J. Brod , Ernesto F. Galvão

Research on quantum states often focuses on the correlation between nonlocal effects and local unitary invariants, among which local unitary equivalence plays a significant role in quantum state classification and resource theories. This…

Quantum Physics · Physics 2025-11-17 Lin Zhang , Bing Xie , Yuanhong Tao

Bargmann invariants, also known as multivariate traces of quantum states $\operatorname{Tr}(\rho_1 \rho_2 \cdots \rho_n)$, are unitary invariant quantities used to characterize weak values, Kirkwood-Dirac quasiprobabilities,…

Quantum Physics · Physics 2025-10-16 Sagar Silva Pratapsi , João Gouveia , Leonardo Novo , Ernesto F. Galvão

Considerable effort has been devoted to developing techniques for witnessing and characterizing quantum resources that emerge from collective properties of a set of states. In this context, Bargmann invariants play a central role: they…

Quantum Physics · Physics 2026-05-19 Rafael Wagner

Certain unitary-invariants, known as Bargmann invariants or multivariate traces of quantum states, have recently gained attention due to their applications in quantum information theory. However, determining the boundaries of sets of…

Quantum Physics · Physics 2025-04-14 Lin Zhang , Bing Xie , Bo Li

Bargmann invariants, a class of gauge-invariant quantities arising from the overlaps of quantum state vectors, provide a profound and unifying framework for understanding the geometric structure of quantum mechanics. This survey offers a…

Quantum Physics · Physics 2026-01-06 Lin Zhang , Bing Xie

Bargmann invariants of order $n$, defined as multivariate traces of quantum states $\text{Tr}[\rho_1\rho_2 \ldots \rho_n]$, are useful in applications ranging from quantum metrology to certification of nonclassicality. A standard quantum…

Quantum Physics · Physics 2025-12-19 Kyrylo Simonov , Rafael Wagner , Ernesto Galvão

Bargmann invariants have recently emerged as powerful tools in quantum information theory, with applications ranging from geometric phase characterization to quantum state distinguishability. Despite their widespread use, a complete…

Quantum Physics · Physics 2025-11-13 Jianwei Xu

Weak values and Kirkwood--Dirac (KD) quasiprobability distributions have been independently associated with both foundational issues in quantum theory and advantages in quantum metrology. We propose simple quantum circuits to measure weak…

The imaginary in quantum theory plays a crucial role in describing quantum coherence and is widely applied in quantum information tasks such as state discrimination, pseudorandomness generation, and quantum metrology. A recent paper by…

Quantum Physics · Physics 2024-12-12 Mao-Sheng Li , Yi-Xi Tan

Quantum theory is traditionally formulated using complex numbers. This imaginarity of quantum theory has been quantified as a resource with applications in discrimination tasks, pseudorandomness generation, and quantum metrology. Here we…

Quantum Physics · Physics 2024-11-15 Carlos Fernandes , Rafael Wagner , Leonardo Novo , Ernesto F. Galvão

Traditionally, the characterization of quantum resources has focused on individual quantum states. Recent literature, however, has increasingly explored the characterization of resources in multi-states (ordered collections of states…

Quantum Physics · Physics 2026-01-21 Mao-Sheng Li , Rafael Wagner , Lin Zhang

Set coherence is a basis-independent relational form of quantum coherence: a finite family of quantum states is set incoherent exactly when all its members are diagonal in one common basis. We determine how much low-order Bargmann data are…

Quantum Physics · Physics 2026-05-12 Yan-Ling Wang

We study the invariants of arbitrary dimensional multipartite quantum states under local unitary transformations. For multipartite pure states, we give a set of invariants in terms of singular values of coefficient matrices. For…

Quantum Physics · Physics 2015-09-04 Ting-Gui Zhang , Ming-Jing Zhao , Xianqing Li-Jost , Shao-Ming Fei

This paper addresses the problem of checking invariant properties for a large class of symbolic transition systems, defined by a combination of SMT theories and quantifiers. State variables can be functions from an uninterpreted sort…

Logic in Computer Science · Computer Science 2024-03-01 Gianluca Redondi , Alessandro Cimatti , Alberto Griggio , Kenneth McMillan

The quantification of the quantumness of a quantum ensemble has theoretical and practical significance in quantum information theory. We propose herein a class of measures of the quantumness of quantum ensembles using the unitary similarity…

Quantum Physics · Physics 2018-03-28 Xianfei Qi , Ting Gao , Fengli Yan

Commutators are essential in quantum information theory, influencing quantum state symmetries and information storage robustness. This paper systematically investigates the characteristics of bipartite and multipartite quantum states…

Quantum Physics · Physics 2025-04-15 Shu Li , Jie Wang , Binfeng Wang , Lin Chen

Quantum causality extends the conventional notion of fixed causal structure by allowing channels and operations to act in an indefinite causal order. The importance of such an indefinite causal order ranges from the foundational---e.g.…

Quantum Physics · Physics 2020-09-29 K. Goswami , J. Romero

We derive the invariant measure on the manifold of multimode quantum Gaussian states, induced by the Haar measure on the group of Gaussian unitary transformations. To this end, by introducing a bipartition of the system in two disjoint…

Quantum Physics · Physics 2013-01-07 C. Lupo , S. Mancini , A. De Pasquale , P. Facchi , G. Florio , S. Pascazio

The quantum switch, the canonical example of a process with indefinite causal order, has been claimed to provide various advantages over processes with definite causal orders for some particular tasks in the field of quantum metrology. In…

Quantum Physics · Physics 2024-06-27 Raphaël Mothe , Cyril Branciard , Alastair A. Abbott
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