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We experimentally demonstrate a two-particle collective measurement proposed as the optimal solution to a quantum state estimation game. Our results suggest that, in practice, the collective measurement strategy is at least as good as the…

Quantum Physics · Physics 2026-02-05 Arman Mansouri , Kyle M. Jordan , Raphael A. Abrahao , Jeff S. Lundeen

By viewing entanglement as a state function, a new kind of phase transition takes place: the geometric phase transition. This phenomenon occurs due to singularities in the shape of the entangled states set. It is shown how this result can…

Quantum Physics · Physics 2007-05-23 Daniel Cavalcanti , Fernando G. S. L. Brandao , Marcelo O. Terra Cunha

It is proposed a possible new approach of quantum measurements (QMS), disconnected of the traditional interpretation of uncertainty relations and independent of any appeal to the strange idea of collapse (reduction) of wave functions. The…

Quantum Physics · Physics 2007-05-23 S. Dumitru

In the absence of a reference frame for transformations associated with a group G, any quantum state that is non-invariant under the action of G may serve as a token of the missing reference frame. We here introduce a novel measure of the…

Quantum Physics · Physics 2009-07-14 Gilad Gour , Iman Marvian , Robert W. Spekkens

It is proposed to give up the description of physical states in terms of ensembles of state vectors with various probabilities, relying instead solely on the density matrix as the description of reality. With this definition of a physical…

Quantum Physics · Physics 2015-06-19 Steven Weinberg

The theory of continuous quantum measurement allows to reconstruct the state $\rho_t$ of a system from a continuous stochastic measurement record $I_t$. However, this truly continuous-time signal $I_t$ is never available in practice. In…

Quantum Physics · Physics 2025-05-28 Pierre Guilmin , Pierre Rouchon , Antoine Tilloy

Mixed-state phase transitions have recently attracted growing attention as a new frontier in nonequilibrium quantum matter and quantum information. In this work, we introduce the measurement-dressed imaginary-time evolution (MDITE) as a…

Quantum Physics · Physics 2026-03-06 Yi-Ming Ding , Zenan Liu , Xu Tian , Zhe Wang , Yanzhang Zhu , Zheng Yan

Recently several more efficient versions of quantum state tomography have been proposed, with the purpose of making tomography feasible even for many-qubit states. The number of state parameters to be estimated is reduced by tentatively…

Quantum Physics · Physics 2015-05-27 J. O. S. Yin , S. J. van Enk

How can we quantify the entanglement in a quantum state, if only the expectation value of a single observable is given? This question is of great interest for the analysis of entanglement in experiments, since in many multiparticle…

Quantum Physics · Physics 2008-05-16 O. Gühne , M. Reimpell , R. F. Werner

Starting from a new understanding of the vacuum energy problem based on the combination of the phase space regularization and the holographic bound, we argue that quantum gravity should be understood as gravitized quantum theory, that is,…

High Energy Physics - Theory · Physics 2024-07-10 Tristan Hübsch , Djordje Minic

Introduced recently approach based on tomographic probability distribution of quantum states is shown to be closely related with the known notion of the quantum probability measures discussed in quantum information theory and positive…

Quantum Physics · Physics 2007-05-23 G. G. Amosov , V. I. Man'ko

In this paper, the distinguishability of multipartite geometrically uniform quantum states obtained from a single reference state is studied in the symmetric subspace. We specially focus our attention on the unitary transformation in a way…

Quantum Physics · Physics 2015-03-24 M. A. Jafarizadeh , P. Sadeghi , d. Akhgar , P. Mahmoudi

A fully geometric procedure of quantization that utilizes a natural and necessary metric on phase space is reviewed and briefly related to the goals of the program of geometric quantization.

Quantum Physics · Physics 2007-05-23 John R. Klauder

Based on the adiabatic geometric phase concerning with density matrix[1] , we extend it to the sub-geometric phase in the non-adiabatic case. It is found that whatever the real part or imaginary part of the sub-geometric phase can play an…

Quantum Physics · Physics 2024-05-20 Zheng-Chuan Wang

Quantum physics, despite its observables being intrinsically of a probabilistic nature, does not have a quantum entropy assigned to them. We propose a quantum entropy that quantify the randomness of a pure quantum state via a conjugate pair…

Quantum Physics · Physics 2022-10-05 Davi Geiger , Zvi M. Kedem

We introduce a new kind of quantum measurement that is defined to be symmetric in the sense of uniform Fisher information across a set of parameters that injectively represent pure quantum states in the neighborhood of a fiducial pure…

Quantum Physics · Physics 2016-05-11 Nan Li , Christopher Ferrie , Jonathan A. Gross , Amir Kalev , Carlton M. Caves

We analyze the geometry of a joint distribution over a set of discrete random variables. We briefly review Shannon's entropy, conditional entropy, mutual information and conditional mutual information. We review the entropic information…

Quantum state tomography (QST) is the process of reconstructing the state of a quantum system (mathematically described as a density matrix) through a series of different measurements, which can be solved by learning a parameterized…

Quantum Physics · Physics 2025-03-31 Hailan Ma , Zhenhong Sun , Daoyi Dong , Chunlin Chen , Herschel Rabitz

We consider symmetry as a foundational concept in quantum mechanics and rewrite quantum mechanics and measurement axioms in this description. We argue that issues related to measurements and physical reality of states can be better…

Quantum Physics · Physics 2018-04-11 Houri Ziaeepour

One of the key tasks in physics is to perform measurements in order to determine the state of a system. Often, measurements are aimed at determining the values of physical parameters, but one can also ask simpler questions, such as "is the…

Quantum Physics · Physics 2021-07-01 Jan de Boer , Victor Godet , Jani Kastikainen , Esko Keski-Vakkuri