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We study nonclassical correlations beyond entanglement in a family of two-mode non-Gaussian states which represent the continuous-variable counterpart of two-qubit Werner states. We evaluate quantum discord and other quantumness measures…

Quantum Physics · Physics 2015-06-03 Richard Tatham , Ladislav Mišta , Gerardo Adesso , Natalia Korolkova

Continuous-variable (CV) quantum key distribution (QKD) employs the quadratures of a bosonic mode to establish a secret key between two remote parties, and this is usually achieved via a Gaussian modulation of coherent states. The resulting…

Injecting a non-Gaussian (Fock or Shr\"odinger cat) quantum state into the dark port of a two-arm interferometer and a strong classical light into the bright one, it is possible, in principle, to detect a given phase shift unambiguously…

Quantum Physics · Physics 2024-05-14 V. L. Gorshenin , F. Ya. Khalili

We consider a weakly interacting coherently coupled Bose-Einstein condensate in a double-well potential. We show by means of stochastic simulations that the system could possibly be driven to an entangled macroscopic superposition state or…

Statistical Mechanics · Physics 2022-09-21 J. Ruostekoski

Schr\"odinger's cat originates from the famous thought experiment querying the counterintuitive quantum superposition of macroscopic objects. As a natural extension, several "cats" (quasi-classical objects) can be prepared into coherent…

Non-Gaussian quantum states of light are critical resources for optical quantum information processing, but methods to generate them efficiently remain challenging to implement. Here we introduce a generic approach for non-Gaussian state…

We propose a deterministic, measurement-free implementation of a cubic phase gate for continuous-variable quantum information processing. In our scheme, the applications of displacement and squeezing operations allow us to engineer the…

We study the dissipative preparation of pure non-Gaussian states of a target mode which is coupled both linearly and quadratically to an auxiliary damped mode. We show that any pure state achieved independently of the initial condition is…

Quantum Physics · Physics 2019-07-19 Matteo Brunelli , Oussama Houhou

Continuous-variable bosonic systems stand as prominent candidates for implementing quantum computational tasks. While various necessary criteria have been established to assess their resourcefulness, sufficient conditions have remained…

Quantum Physics · Physics 2024-10-08 Cameron Calcluth , Nicolas Reichel , Alessandro Ferraro , Giulia Ferrini

We introduce a novel measure to quantify the non-Gaussian character of a quantum state: the quantum relative entropy between the state under examination and a reference Gaussian state. We analyze in details the properties of our measure and…

Quantum Physics · Physics 2009-01-07 Marco G. Genoni , Matteo G. A. Paris , Konrad Banaszek

We propose a method to deterministically entangle qubits or ensembles of qubits interacting with a shared bosonic mode in the ultrastrong coupling regime. We show that the resulting gate is a product of two unitaries: one unitary acts only…

Quantum Physics · Physics 2025-09-03 Ebubechukwu O. Ilo-Okeke , Tongzhou Wang , Valentin Ivannikov , Tim Byrnes

Quantum metrology with nonclassical states offers a promising route to improved precision in physical measurements. The quantum effects of Schr{\"o}dinger-cat superpositions or entanglements allow measurement uncertainties to reach below…

Quantum Physics · Physics 2025-07-11 Y. A. Yang , W. -T. Luo , J. -L. Zhang , S. -Z. Wang , Chang-Ling Zou , T. Xia , Z. -T. Lu

We propose a measure for the "size" of a Schroedinger cat state, i.e. a quantum superposition of two many-body states with (supposedly) macroscopically distinct properties, by counting how many single-particle operations are needed to map…

Quantum Physics · Physics 2008-07-22 Florian Marquardt , Benjamin Abel , Jan von Delft

This review covers recent theoretical and experimental efforts to extend the application of the continuous-variable quantum technology of light beyond "Gaussian" quantum states, such as coherent and squeezed states, into the domain of…

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

We explore the relative advantages in continuous-variable quantum teleportation when non-Gaussian operations, namely, photon subtraction, addition, and catalysis, are performed before and after interaction with a noisy channel. We generate…

Quantum Physics · Physics 2024-06-28 Chandan Kumar , Mohak Sharma , Shikhar Arora

We discuss the generation of a Schr\"odinger cat in a nanocavity created by the coupling of an electromagnetic mode with an exciton in a quantum dot considering the dispersive limit of the Jaynes-Cummings model. More than the generation…

Quantum Physics · Physics 2024-06-26 J. Lira , L. Sanz

We propose a scheme to create a macroscopic ``Sch\"odinger cat'' state formed by two interacting Bose condensates. In analogy with quantum optics, where the control and engineering of quantum states can be maintained to a large extend, we…

Quantum Physics · Physics 2009-10-30 J. I. Cirac , M. Lewenstein , K. Moelmer , P. Zoller

Continuous-variable cluster states (CVCSs) can be supplemented with Gottesman-Kitaev-Preskill (GKP) states to form a hybrid cluster state with the power to execute universal, fault-tolerant quantum computing in a measurement-based fashion.…

Quantum Physics · Physics 2021-08-09 Giacomo Pantaleoni , Ben Q. Baragiola , Nicolas C. Menicucci

We present a nonlinear stochastic Schroedinger equation for pure states describing non-Markovian diffusion of quantum trajectories. It provides an unravelling of the evolution of a quantum system coupled to a finite or infinite number of…

Quantum Physics · Physics 2009-10-31 L. Diosi , N. Gisin , W. T. Strunz