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We study quantum statistical inference tasks of hypothesis testing and their canonical variations, in order to review relations between their corresponding figures of merit---measures of statistical distance---and demonstrate the crucial…

Quantum Physics · Physics 2020-09-25 Marcin Jarzyna , Jan Kolodynski

We derive an exact expression for the quantumness of a Hilbert space (defined in quant-ph/0302092), and show that in composite Hilbert spaces the signal states must contain at least some entangled states in order to achieve such a…

Quantum Physics · Physics 2007-05-23 Christopher A. Fuchs

In this work we study the properties of an purification-based entropic metric for measuring the distance between both quantum states and quantum processes. This metric is defined as the square root of the entropy of the average of two…

Quantum Physics · Physics 2015-06-15 Tristan M. Osan , Pedro W. Lamberti

Quantification of coherence lies at the heart of quantum information processing and fundamental physics. Exact evaluation of coherence measures generally needs a full reconstruction of the density matrix, which becomes intractable for…

Quantum Physics · Physics 2021-06-28 Qi-Ming Ding , Xiao-Xu Fang , Xiao Yuan , Ting Zhang , He Lu

We study the connection between the Hilbert-Schmidt measure of entanglement (that is the minimal distance of an entangled state to the set of separable states) and entanglement witness in terms of a generalized Bell inequality which…

In the past decades, quantum entanglement has been recognized to be the basic resource in quantum information theory. A fundamental need is then the understanding its qualification and its quantification: Is the quantum state entangled, and…

Quantum Physics · Physics 2013-02-20 Szilárd Szalay

Quantum metrology exploits quantum mechanical laws to improve the precision in estimating technologically relevant parameters such as phase, frequency, or magnetic fields. Probe states are usually tailored on the particular dynamics whose…

The entanglement measure for multiqudits is proposed. This measure calculates the partial entanglement distributed by subsystems and the complete entanglement of the total system. This shows that we need to measure the subsystem…

Quantum Physics · Physics 2007-05-23 Hyuk-jae Lee , Sung Dahm Oh , Doyeol Ahn

We show that distances of objects at cosmological distances can be measured directly using interferometry. Our approach to interferometric parallax comes from analysis of 4-point amplitude and intensity correlations that can be generated…

Astrophysics · Physics 2008-11-26 Pankaj Jain , John P. Ralston

The geometry of quantum states provides a unifying framework for estimation processes based on quantum probes, and it allows to derive the ultimate bounds of the achievable precision. We show a relation between the statistical distance…

Quantum Physics · Physics 2016-11-28 Paolo Giorda , Michele Allegra

Entanglement is not only fundamental for understanding multipartite quantum systems but also generally useful for quantum information applications. Despite much effort devoted so far, little is known about minimal resources for detecting…

Quantum Physics · Physics 2016-06-02 Chang Jian Kwong , Simone Felicetti , Leong Chuan Kwek , Joonwoo Bae

We address the issue of quantifying the non-Gaussian character of a bosonic quantum state and introduce a non-Gaussianity measure based on the Hilbert-Schmidt distance between the state under examination and a reference Gaussian state. We…

Quantum Physics · Physics 2009-11-13 Marco G. Genoni , Matteo G. A. Paris , Konrad Banaszek

The effects of any quantum measurement can be described by a collection of measurement operators {M_m} acting on the quantum state of the measured system. However, the Hilbert space formalism tends to obscure the relationship between the…

Quantum Physics · Physics 2009-11-07 Holger F. Hofmann

In general, classical measurement statistics of a quantum measurement is disturbed by performing an additional incompatible quantum measurement beforehand. Using this observation, we introduce a state-independent definition of disturbance…

Quantum Physics · Physics 2016-05-04 S. S. Zhou , Shengjun Wu , H. F. Chau

We describe and realize an experimental procedure for assessing the incompatibility of two qubit measurements. The experiment consists in a state discrimination task where either measurement is used according to some partial intermediate…

The presence of quantum correlations in a quantum state is related to the state response to local unitary perturbations. Such response is quantified by the distance between the unperturbed and perturbed states, minimized with respect to…

Quantum Physics · Physics 2014-08-25 W. Roga , S. M. Giampaolo , F. Illuminati

We report a new metric of quantum states. This metric is build up from super-fidelity, which has deep connection with the Uhlmann-Jozsa fidelity and plays an important role in quantifying entanglement. We find that the new metric possess…

Quantum Physics · Physics 2009-08-24 Zhi-Hao Ma , Fu-Lin Zhang , Zhi-Hua Chen , Jing-Ling Chen

Quantum Wasserstein divergences are modified versions of quantum Wasserstein distances defined by channels, and they are conjectured to be genuine metrics on quantum state spaces by De Palma and Trevisan. We prove triangle inequality for…

Mathematical Physics · Physics 2025-04-03 Gergely Bunth , József Pitrik , Tamás Titkos , Dániel Virosztek

We report the creation of a wide range of quantum states with controllable degrees of entanglement and entropy using an optical two-qubit source based on spontaneous parametric downconversion. The states are characterised using measures of…

Quantum Physics · Physics 2009-11-07 A. G. White , D. F. V. James , W. J. Munro , P. G. Kwiat

We derive upper bounds for Hilbert-Schmidt's quantum coherence of general states of a $d$-level quantum system, a qudit, in terms of its incoherent uncertainty, with the latter quantified using the linear and von Neumann's entropies of the…

Quantum Physics · Physics 2020-07-22 Marcos L. W. Basso , Diego S. S. Chrysosthemos , Jonas Maziero