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Generalizing the well-known spin-squeezing inequalities, we study the relation between squeezing of collective $N$-particle $su(d)$ operators and many-body entanglement geometry in multi-particle systems. For that aim, we define the set of…

Quantum Physics · Physics 2025-09-03 Giuseppe Vitagliano , Otfried Gühne , Géza Tóth

Multi-mode squeezing and entanglement are important resources in quantum metrology and sensing. For spin-1/2 Bose-Einstein condensates subject to spin-orbit coupling (SOC), previous studies on spin squeezing have been limited to two-mode…

Quantum Gases · Physics 2025-08-07 Fei Zhu , Zheng Tang , Liang Zeng , Shu Wang , Li Chen

This dissertation studies spin squeezing, entanglement and decoherence in large ensembles of cold, trapped alkali atoms with hyperfine spin f interacting with optical fields. Restricting the state of each atom to a qutrit embedded in the…

Quantum Physics · Physics 2014-10-02 Leigh M. Norris

The spin-statistics theorem is generalized to include quantum entanglement. Specifically, within the context of spin entanglement, we prove that isotropic spin-correlated (ISC) states must occur in pairs. This pairing process can be…

General Physics · Physics 2024-06-17 Paul O'Hara

The concept of entanglement entropy appears in multiple contexts, from black hole physics to quantum information theory, where it measures the entanglement of quantum states. We investigate the entanglement entropy in a simple model, the…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Karyn Le Hur

We propose an experimentally accessible scheme to determine lower bounds on the quantum Fisher information (QFI), which ascertains multipartite entanglement or usefulness for quantum metrology. The scheme is based on comparing the…

Quantum Physics · Physics 2016-03-14 Florian Fröwis , Pavel Sekatski , Wolfgang Dür

Entanglement between individual spins can be detected by using thermodynamics quantities as entanglement witnesses. This applies to collective spins also, provided that their internal degrees of freedom are frozen, as in the limit of…

Mesoscale and Nanoscale Physics · Physics 2013-11-21 F. Troiani , S. Carretta , P. Santini

We study squeezing of the spin uncertainties by quantum non-demolition (QND) measurement in non-polarized spin ensembles. Unlike the case of polarized ensembles, the QND measurements can be performed with negligible back-action, which…

Quantum Physics · Physics 2010-05-20 Geza Toth , Morgan W. Mitchell

We show that spin squeezing implies entanglement for quantum tripartite-state, where the subsystem of the bipartite-state is identical. We study the relation between spin squeezing parameters and entanglement through the quantum entropy of…

Quantum Physics · Physics 2015-03-13 M. S. Ateto

We study experimentally accessible lower bounds on entanglement measures based on entropic uncertainty relations. Experimentally quantifying entanglement is highly desired for applications of quantum simulation experiments to fundamental…

Quantum Physics · Physics 2021-05-25 Bjarne Bergh , Martin Gärttner

Entanglement is a fundamental feature of quantum mechanics and holds great promise for enhancing metrology and communications. Much of the focus of quantum metrology so far has been on generating highly entangled quantum states that offer…

We discuss on general grounds some local indicators of entanglement, that have been proposed recently for the study and classification of quantum phase transitions. In particular, we focus on the capability of entanglement in detecting…

Quantum Physics · Physics 2007-05-23 L. Campos Venuti , C. Degli Esposti Boschi , G. Morandi , M. Roncaglia , A. Scaramucci

Entanglement generation and detection are two of the most sought-after goals in the field of quantum control. Besides offering a means to probe some of the most peculiar and fundamental aspects of quantum mechanics, entanglement in…

Mesoscale and Nanoscale Physics · Physics 2011-11-29 M. S. Rudner , L. M. K. Vandersypen , V. Vuletic , L. S. Levitov

The concept of randomized measurements on individual particles has proven to be useful for analyzing quantum systems and is central for methods like shadow tomography of quantum states. We introduce $\textit{collective}$ randomized…

Quantum Physics · Physics 2024-08-12 Satoya Imai , Géza Tóth , Otfried Gühne

Spin squeezing of collective atomic spins can be achieved conditionally via probing with light and subsequent homodyne detection, as is done in a Quantum Nondemolition measurement. Recently it has been shown that squeezing can also be…

Quantum Physics · Physics 2013-05-29 Denis V. Vasilyev , Christine A. Muschik , Klemens Hammerer

Intra-particle entanglement of individual particles such as neutrons could enable another class of scattering probes that are sensitive to entanglement in quantum systems and materials. In this work, we present experimental results…

We study the combined effects of measurements and unitary evolution on the preparation of spin squeezing in an ensemble of atoms interacting with a single electromagnetic field mode inside a cavity. We derive simple criteria that determine…

Quantum Physics · Physics 2024-08-13 Diego Barberena , Anjun Chu , James K. Thompson , Ana Maria Rey

The work is organized in two main topics. At first we will outline the relation between spin squeezing, quantum metrology and entanglement detection, with a particular focus on the last. We will derive spin squeezing criteria for the…

Quantum Physics · Physics 2015-11-26 Giuseppe Vitagliano

The lack of methods to experimentally detect and quantify entanglement in quantum matter impedes our ability to identify materials hosting highly entangled phases, such as quantum spin liquids. We thus investigate the feasibility of using…

Dynamical evolution of quantum mechanical squeezing and entanglement in a two-mode Bose-Einstein condensate (TBEC) with an adiabatic, time-varying Raman coupling is studied by finding analytical expressions for these quantities. In…

Other Condensed Matter · Physics 2009-11-11 S. Choi , N. P. Bigelow