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We provide new operational significance of nonclassicality in nonequilibrium temperature estimation of bosonic baths with Gaussian probe states and Gaussian dynamics. We find a bound on the thermometry performance using classical probe…

Quantum non-Gaussianity, a more potent and highly useful form of nonclassicality, excludes all convex mixtures of Gaussian states and Gaussian parametric processes generating them. Here, for the first time, we conclusively test quantum…

Entangled states, like the two-mode squeezed vacuum state, are known to give quantum advantage in the illumination protocol, a method to detect a weakly reflecting target submerged in a thermal background. We use non-Gaussian photon-added…

Quantum Physics · Physics 2024-04-03 Rivu Gupta , Saptarshi Roy , Tamoghna Das , Aditi Sen De

Quantum non-Gaussian states are crucial for the fundamental understanding of non-linear bosonic systems and simultaneously advanced applications in quantum technologies. In many bosonic experiments the important quantum non-Gaussian feature…

Quantum Physics · Physics 2025-10-07 Jan Provazník , Petr Marek , Julien Laurat , Radim Filip

A general state of an $m\otimes n$ system is a classical-quantum state if and only if its associated $A$-correlation matrix (a matrix constructed from the coherence vector of the party $A$, the correlation matrix of the state, and a…

Quantum Physics · Physics 2016-04-19 S. Javad Akhtarshenas , Hamidreza Mohammadi , Saman Karimi , Zahra Azmi

Photon addition and subtraction render Gaussian states non-Gaussian. We provide a quantitative analysis of the change in nonclassicality produced by these processes by analyzing the Wigner negativity and quadrature coherence scale (QCS) of…

Quantum Physics · Physics 2023-05-10 Anaelle Hertz , Stephan De Bièvre

The state of the spatially correlated down-converted photons is usually treated as a two-mode Gaussian entangled state. While intuitively this seems to be reasonable, it is known that new structures in the spatial distributions of these…

Quantum Physics · Physics 2015-03-19 E. S. Gómez , W. A. T. Nogueira , C. H. Monken , G. Lima

Coarse graining is a common imperfection of realistic quantum measurement, obstructing the direct observation of quantum features. Under highly coarse-grained measurement, we experimentally detect the continuous-variable nonclassicality of…

Quantum Physics · Physics 2023-10-19 Chan Roh , Young-Do Yoon , Jiyong Park , Young-Sik Ra

Gaussian quantum discord is a measure of quantum correlations in Gaussian systems. Using Gaussian discord we quantify the quantum correlations of a bipartite entangled state and a separable two-mode mixture of coherent states. We…

Quantum Physics · Physics 2012-08-13 Lars S. Madsen , Adriano Berni , Mikael Lassen , Ulrik L. Andersen

The quantumness of a generic state is the resource of many applications in quantum information theory and it is interesting to survey the measures which are able to detect its trace in the properties of the state. In this work we study the…

Quantum Physics · Physics 2016-04-26 Javad Behdani , Seyed Javad Akhtarshenas , Mohsen Sarbishaei

Entangled two-mode Gaussian states are a key resource for quantum information technologies such as teleportation, quantum cryptography and quantum computation, so quantification of Gaussian entanglement is an important problem. Entanglement…

Quantum Physics · Physics 2018-01-03 Spyros Tserkis , Timothy C. Ralph

We present a class of non-Gaussian two-mode continuous variable states for which the separability criterion for Gaussian states can be employed to detect whether they are separable or not. These states reduce to the two-mode Gaussian states…

Quantum Physics · Physics 2016-08-16 Derek McHugh , Vladimír Bužek , Mário Ziman

Continuous-variable quantum systems are foundational to quantum computation, communication, and sensing. While traditional representations using wave functions or density matrices are often impractical, the tomographic picture of quantum…

Quantum Physics · Physics 2026-03-17 Liubov A. Markovich , Xiaoyu Liu , Jordi Tura

Graph states are the backbone of measurement-based continuous-variable quantum computation. However, experimental realisations of these states induce Gaussian measurement statistics for the field quadratures, which poses a barrier to obtain…

Quantum Physics · Physics 2018-11-30 Mattia Walschaers , Supratik Sarkar , Valentina Parigi , Nicolas Treps

Geometric discord, a measure of quantumness of bipartite system, captures minimal nonlocal effects of a quantum state due to locally invariant von Neumann projective measurements. Original version of this measure is suffered by the local…

Quantum Physics · Physics 2019-06-10 R. Muthuganesan , V. K. Chandrasekar

Cavity quantum optomechanics has emerged as a new platform for quantum science and technology with applications ranging from quantum-information processing to tests of the foundations of physics. Of crucial importance for optomechanics is…

Quantum Physics · Physics 2022-06-02 Lydia A. Kanari-Naish , Jack Clarke , Sofia Qvarfort , Michael R. Vanner

In this didactic article we explore the concept of quantum correlations beyond entanglement. We begin by introducing and motivating the classically correlated states and then showing how to quantify the quantum correlations using an…

Quantum Physics · Physics 2016-11-08 Gerardo Adesso , Marco Cianciaruso , Thomas R. Bromley

Measures of quantum properties are essential to understanding the fundamental differences between quantum and classical systems as well as quantifying resources for quantum technologies. Here two broad classes of bosonic phase-space…

Quantum Physics · Physics 2021-05-11 Benjamin Kühn , Werner Vogel , Valérian Thiel , Sofiane Merkouche , Brian J. Smith

We present a reliable algorithm to evaluate quantum discord for general two--qubit states, amending and extending an approach recently put forward for the subclass of X--states. A closed expression for the discord of arbitrary states of two…

Quantum Physics · Physics 2011-05-23 Davide Girolami , Gerardo Adesso

We present a general analysis of the state obtained by subjecting the output from a continuous-wave (cw) Gaussian field to non-Gaussian measurements. The generic multimode state of cw Gaussian fields is characterized by an infinite…

Quantum Physics · Physics 2009-11-13 Klaus Molmer