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Continuous-variable Gaussian entanglement is an attractive notion, both as a fundamental concept in quantum information theory, based on the well-established Gaussian formalism for phase-space variables, and as a practical resource in…

Quantum Physics · Physics 2026-05-07 E. Shchukin , P. van Loock

Addition of single photons to two-mode-squeezed-vacuum states has the effect of distilling quantum entanglement, and, when deployed in quantum key distribution, should lead also to an increase in the secret key rate. However, the extraction…

Quantum Physics · Physics 2025-07-25 Hao Jeng , Ping Koy Lam , Syed M. Assad

Nonclassical properties of photon added and subtracted displaced Fock states have been studied using various witnesses of lower- and higher-order nonclassicality. Compact analytic expressions are obtained for the nonclassicality witnesses.…

A Macro-state consisting of N= 3.5 x 10^4 photons in a quantum superposition and entangled with a far apart single-photon state (Micro-state) is generated. Precisely, an entangled photon pair is created by a nonlinear optical process, then…

Quantum Physics · Physics 2009-11-13 Francesco De Martini , Fabio Sciarrino , Chiara Vitelli

Multipartite entanglement is an essential resource for quantum information tasks, but characterizing entanglement structures in continuous variable systems remains challenging, especially in multimode non-Gaussian scenarios. In this work,…

Quantum Physics · Physics 2025-11-03 Mingsheng Tian , Xiaoting Gao , Boxuan Jing , Feng-Xiao Sun , Matteo Fadel , Manuel Gessner , Qiongyi He

Bosonic Gaussian states are ubiquitous in quantum optics and condensed matter physics. While they are efficiently handled within the Gaussian formalism, sampling requires calculating amplitudes in the boson occupation basis. This step,…

Quantum Physics · Physics 2026-05-12 Tong Liu , Hui-Ke Jin , Tao Xiang , Hong-Hao Tu

We propose a resource-efficient error-rejecting entangled-state analyzer for polarization-encoded multiphoton systems. Our analyzer is based on two single-photon quantum-nondemolition detectors, where each of them is implemented with a…

Quantum Physics · Physics 2019-11-13 Tao Li , Adam Miranowicz , Keyu Xia , Franco Nori

We present a novel, non-parametric form for compactly representing entangled many-body quantum states, which we call a `Gaussian Process State'. In contrast to other approaches, we define this state explicitly in terms of a configurational…

Strongly Correlated Electrons · Physics 2020-11-11 Aldo Glielmo , Yannic Rath , Gabor Csanyi , Alessandro De Vita , George H. Booth

Using a spontaneous-downconversion photon source, we produce true non-maximally entangled states, i.e., without the need for post-selection. The degree and phase of entanglement are readily tunable, and are characterized both by a standard…

Quantum Physics · Physics 2009-10-31 Andrew G. White , Daniel F. V. James , Philippe H. Eberhard , Paul G. Kwiat

Non-Gaussian bosonic states are ubiquitous in interacting light--matter systems, many-body platforms, and relativistic quantum field settings, but their quantitative characterization is hindered by the infinite-dimensional Hilbert space and…

Quantum Physics · Physics 2026-03-17 Federico Centrone , Juan Pablo Paz , Augusto Roncaglia

As an aid to understanding the {\it displacement operator} definition of squeezed states for arbitrary systems, we investigate the properties of systems where there is a Holstein-Primakoff or Bogoliubov transformation. In these cases the…

Quantum Physics · Physics 2015-06-26 Michael Martin Nieto , D. Rodney Truax

In continuous-variable quantum information, non-Gaussian entangled states that are obtained from Gaussian entangled states via photon subtraction are known to contain more entanglement. This makes them better resources for quantum…

Quantum Physics · Physics 2015-08-25 Kaushik P. Seshadreesan , Jonathan P. Dowling , Girish S. Agarwal

We study the tomography of multispin quantum states in the context of finite-dimensional Wigner representations. An arbitrary operator can be completely characterized and visualized using multiple shapes assembled from linear combinations…

Quantum Physics · Physics 2018-01-16 David Leiner , Robert Zeier , Steffen J. Glaser

We study a simple, effective and robust method for entangling two separate stationary quantum dot spin qubits with high fidelity using multiphoton Gaussian state. The fluorescence signals from the two dots interfere at a beam splitter. The…

Quantum Physics · Physics 2013-12-16 Guy Z. Cohen , L. J. Sham

We investigate the systematic use of the Schwinger representation, by virtue of which two boson fields are equivalent to an effective spin, for casting multimode squeezed states into multipartite spin entangled states. The motivation for…

Quantum Physics · Physics 2015-06-17 Niranjan Sridhar , Olivier Pfister

Entanglement is a powerful concept with an enormous potential for scientific and technological advances. A central focus in modern research is to extend the generation and control of entangled states from few to many qubits, and protect…

Quantum Physics · Physics 2024-06-04 Philip Thomas , Leonardo Ruscio , Olivier Morin , Gerhard Rempe

We introduce a protocol for generating a broad class of non-Gaussian (nG) quantum states via postselected weak measurement techniques. The scheme involves injecting an arbitrary quantum state and a single photon into the signal and idler…

Quantum Physics · Physics 2025-12-29 Xiao-Xi Yao , Yusuf Turek

We present a physical setup with which it is possible to produce arbitrary symmetric long-lived multiqubit entangled states in the internal ground levels of photon emitters, including the paradigmatic GHZ and W states. In the case of three…

Quantum Physics · Physics 2015-05-13 T. Bastin , C. Thiel , J. von Zanthier , L. Lamata , E. Solano , G. S. Agarwal

We construct nonlinear coherent states for the Susskind-Glogower operators by the application of the displacement operator on the vacuum state. We also construct nonlinear coherent states as eigenfunctions of a Hamiltonian constructed with…

Magnons can serve as a bridge between spin, phonon, and photon systems, which renders them suitable for constructing hybrid systems. An important application of such hybrid systems is generating entanglement between different platforms. As…

Quantum Physics · Physics 2025-09-04 Zeyu Zhang , Clemens Gneiting , Zheng-Yang Zhou , Ai-Xi Chen