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The quasiprobability representation of quantum states addresses two main concerns, the identification of nonclassical features and the decomposition of the density operator. While the former aspect is a main focus of current research, the…

Quantum Physics · Physics 2018-10-26 J. Sperling , I. A. Walmsley

The impact of a noisy Gaussian channel on a wide range of non-Gaussian input states is studied in this work. The nonclassical nature of the states, both input and output, is developed by studying the corresponding photon statistics and…

Quantum Physics · Physics 2023-08-04 Ramniwas Meena , Subhashish Banerjee

We study continuous variable systems, in which quantum and classical degrees of freedom are combined and treated on the same footing. Thus all systems, including the inputs or outputs to a channel, may be quantum-classical hybrids. This…

Quantum Physics · Physics 2023-07-26 Lars Dammeier , Reinhard F. Werner

Distillation of entanglement using only Gaussian operations is an important primitive in quantum communication, quantum repeater architectures, and distributed quantum computing. Existing distillation protocols for continuous degrees of…

Quantum Physics · Physics 2013-05-30 Earl T. Campbell , Jens Eisert

We provide a unified graphical calculus for all Gaussian pure states, including graph transformation rules for all local and semi-local Gaussian unitary operations, as well as local quadrature measurements. We then use this graphical…

Quantum Physics · Physics 2011-04-29 Nicolas C. Menicucci , Steven T. Flammia , Peter van Loock

Quantum non-Gaussian gate is a missing piece to the realization of continuous-variable universal quantum operations in the optical system. In a measurement-based implementation of the cubic phase gate, a lowest-order non-Gaussian gate,…

A standard method to obtain information on a quantum state is to measure marginal distributions along many different axes in phase space, which forms a basis of quantum state tomography. We theoretically propose and experimentally…

We generalise the Gaussian formalism of Continuous Variable (CV) systems to describe their interactions with qubits/qudits that result in quantum superpositions of Gaussian processes. To this end, we derive a new set of equations in closed…

Quantum Physics · Physics 2025-10-02 Lorenzo Braccini , Sougato Bose , Alessio Serafini

We develop connections between generalised notions of entanglement and quantum computational devices where the measurements available are restricted, either because they are noisy and/or because by design they are only along Pauli…

Quantum Physics · Physics 2012-01-18 N. Ratanje , S. Virmani

In this work we first collect and generalize several existing non-perturbative models for the interaction between a single two-level qubit detector and a relativistic quantum scalar field in arbitrary curved spacetimes, where the time…

Quantum Physics · Physics 2023-08-16 Erickson Tjoa

Graphs are topological spaces that include broader objects than discretized manifolds, making them interesting playgrounds for the study of quantum phases not realized by symmetry breaking. In particular they are known to support anyons of…

Strongly Correlated Electrons · Physics 2021-10-18 Pramod Padmanabhan , Fumihiko Sugino

The development of emerging technologies in quantum optics demands accurate models that faithfully capture genuine quantum effects. Mature semiclassical approaches reach their limits when confronted with quantized electromagnetic fields,…

A novel theory of hybrid quantum-classical systems is developed, utilizing the mathematical framework of constrained dynamical systems on the quantum-classical phase space. Both, the quantum and the classical descriptions of the respective…

Quantum Physics · Physics 2015-06-16 N. Buric , D. B. Popovic , S. Prvanovic , M. Radonjic

In this paper, we investigate the nonclassicality and non-Gaussianity of a coherent superposed quantum state (CSQS) which is obtained by applying a coherent superposition of field annihilation ($a$) and creation ($a^\dagger$) operators,…

Quantum Physics · Physics 2023-04-14 Deepak , Arpita Chatterjee

We show a general relationship between a superposition of macroscopically distinct states and sensitivity in quantum metrology. Generalized cat states are defined by using an index which extracts the coherence between macroscopically…

Quantum Physics · Physics 2019-09-18 Mamiko Tatsuta , Yuichiro Matsuzaki , Akira Shimizu

Nonclassical states of light and their correlations lie at the heart of quantum optics, serving as fundamental resources that underpin both the exploration of quantum phenomena and the realisation of quantum information protocols. These…

Quantum Physics · Physics 2026-01-29 Jhoan Eusse , Esteban Vasquez , Tom Rivlin , Elizabeth Agudelo

A unified formalism was developed in [S. Adhikary et. al., arXiv:1710.04371 [quant-ph]], for describing non-classicality of states by introducing pseudo projection operators in which both quantum logic and quantum probability are naturally…

Quantum Physics · Physics 2019-07-03 Soumik Adhikary , Sooryansh Asthana , V. Ravishankar

We investigate the construction of coherent states for quantum theories of connections based on graphs embedded in a spatial manifold, as in loop quantum gravity. We discuss the many subtleties of the construction, mainly related to the…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Daniele Oriti , Roberto Pereira , Lorenzo Sindoni

A new operator based condition for distinguishing classical from non-classical states of quantised radiation is developed. It exploits the fact that the normal ordering rule of correspondence to go from classical to quantum dynamical…

Quantum Physics · Physics 2008-11-26 Arvind , N. Mukunda , R. Simon

The name graph state is used to describe a certain class of pure quantum state which models a physical structure on which one can perform measurement-based quantum computing, and which has a natural graphical description. We present the…

Quantum Physics · Physics 2008-01-31 Constanza Riera , Stephane Jacob , Matthew G. Parker