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The determination of ground state properties of quantum systems is a fundamental problem in physics and chemistry, and is considered a key application of quantum computers. A common approach is to prepare a trial ground state on the quantum…

Quantum Physics · Physics 2023-12-13 Harish J. Vallury , Lloyd C. L. Hollenberg

Mutually unbiased bases determine an optimal set of measurements to extract complete information about the quantum state of a system. However, quite often a priori information about the state exist, making some of the measurement bases…

Quantum Physics · Physics 2015-06-12 A. B. Klimov , G. Bjork , L. L. Sanchez-Soto

Classical and quantum Markov networks -- including Gibbs states of commuting local Hamiltonians -- are characterized by the vanishing of conditional mutual information (CMI) between spatially separated subsystems. Adding local dissipation…

Quantum Physics · Physics 2025-02-20 Yifan Zhang , Sarang Gopalakrishnan

The quantum Fisher information (QFI) of certain multipartite entangled quantum states is larger than what is reachable by separable states, providing a metrological advantage. Are these nonclassical correlations strong enough to potentially…

Quantum Physics · Physics 2019-05-03 Florian Fröwis , Matteo Fadel , Philipp Treutlein , Nicolas Gisin , Nicolas Brunner

The quantum Fisher information (QFI) represents a fundamental concept in quantum physics. On the one hand, it quantifies the metrological potential of quantum states in quantum-parameter-estimation measurements. On the other hand, it is…

The origin of non-classical correlations is difficult to identify since the uncertainty principle requires that information obtained about one observable invariably results in the disturbance of any other non-commuting observable. Here,…

Quantum Physics · Physics 2014-07-01 Holger F. Hofmann

Competing scenarios for quantum critical points (QCPs) of strongly interacting Fermi systems signaled by a divergent density of states at zero temperature are contrasted. The conventional scenario, which enlists critical fluctuations of a…

Strongly Correlated Electrons · Physics 2009-04-11 V. A. Khodel , J. W. Clark , M. V. Zverev

The mutual information is a measure of classical and quantum correlations of great interest in quantum information. It is also relevant in quantum many-body physics, by virtue of satisfying an area law for thermal states and bounding all…

Quantum Physics · Physics 2021-09-15 Samuel O. Scalet , Álvaro M. Alhambra , Georgios Styliaris , J. Ignacio Cirac

The effect of quantum steering describes a possible action at a distance via local measurements. Whereas many attempts on characterizing steerability have been pursued, answering the question as to whether a given state is steerable or not…

Quantum Physics · Physics 2018-11-13 Ana C. S. Costa , Roope Uola , Otfried Gühne

Quantum fidelity is a central tool in quantum information, quantifying how much two quantum states are similar. Here we propose a limit formula for the quantum fidelity between a mixed state and a pure state. As an example of an…

Quantum Physics · Physics 2014-10-13 Gaetana Spedalieri , Christian Weedbrook , Stefano Pirandola

Quantum state discrimination is a fundamental concept in quantum information theory, which refers to a class of techniques to identify a specific quantum state through a positive operator-valued measure. In this work, we investigate how…

Quantum Physics · Physics 2025-07-09 Hyunho Cha , Jungwoo Lee

Recent developments in quantum computing suggest that it could be possible to make conditional changes to the state of a quantum mechanical system without resorting to classical observation. It is accomplished through collective response of…

Quantum Physics · Physics 2007-05-23 Sarnath Ramnath , Kevin Haglin

Quantum Fisher Information (QFI) is a fundamental quantity in quantum parameter estimation theory, characterizing the ultimate precision bound of parameter estimation. In this work, we investigate QFI for quantum states in non-Hermitian…

Quantum Physics · Physics 2025-05-27 L. H. Wei , H. J. Xing , L. B. Fu , H. D. Liu

We obtain a maximizer for the quantum mutual information for classical information sent over the quantum qubit amplitude damping channel. This is achieved by limiting the ensemble of input states to antipodal states, in the calculation of…

Quantum Physics · Physics 2011-07-20 Tony Dorlas , Ciara Morgan

We theoretically investigate and experimentally demonstrate a procedure for conditional control and enhancement of an interferometric coupling between two qubits encoded into states of bosonic particles. Our procedure combines local…

Quantum Physics · Physics 2017-01-20 R. Stárek , M. Mičuda , I. Straka , M. Miková , M. Ježek , R. Filip , J. Fiurášek

We develop a theory of indirect measurements where a probe is able to read, in short interaction times, the quantum state of a remote system through an incoherent wall. The probe and the system can interact with an ancilla in an incoherent…

Quantum Physics · Physics 2015-05-14 J. Casanova , G. Romero , I. Lizuain , J. C. Retamal , C. F. Roos , J. G. Muga , E. Solano

We derive a classification and a measure of classical- and quantum-correlation of multipartite qubit, qutrit, and in general, $n$-level systems, in terms of SU$(n)$ representations of density matrices. We compare the measure for the case of…

Quantum Physics · Physics 2010-10-26 Y. B. Band , I. Osherov

Given a quantum state with an unknown parameter, the Quantum Fisher Information (QFI) is a measure of the amount of information that an observable can extract about the parameter. QFI also quantifies the maximum achievable precision in…

Quantum Physics · Physics 2019-08-19 C. S. Sudheer Kumar , T. S. Mahesh

This paper compares and evaluates a set of non-parametric mutual information estimators with the goal of providing a novel toolset to progress in the analysis of the capacity of the nonlinear optical channel, which is currently an open…

Information Theory · Computer Science 2018-01-25 Tommaso Catuogno , Menelaos Ralli Camara , Marco Secondini

The quantum Fisher information (QFI), as a function of quantum states, measures the amount of information that a quantum state carries about an unknown parameter. The (entanglement-assisted) QFI of a quantum channel is defined to be the…

Quantum Physics · Physics 2021-04-06 Sisi Zhou , Liang Jiang