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Multipartite entanglement is the key resource allowing quantum devices to outperform their classical counterparts, and entanglement certification is fundamental to assess any quantum advantage. The only scalable certification scheme relies…

Quantum Physics · Physics 2021-07-28 Irénée Frérot , Tommaso Roscilde

A quantum state's entanglement across a bipartite cut can be quantified with entanglement entropy or, more generally, Schmidt norms. Using only Schmidt decompositions, we present a simple iterative algorithm to maximize Schmidt norms.…

Quantum Physics · Physics 2018-06-14 Robin Reuvers

Entanglement is the central resource of quantum information processing and the precise characterization of entangled states is a crucial issue for the development of quantum technologies. This leads to the necessity of a precise,…

We investigate quantum features and non-classical nature of two-spin-$1/2$ NMR systems at thermal equilibrium under external magnetic fields. More specifically, using suitable quantifiers, we analyze quantum coherence, mixedness, and…

Quantum Physics · Physics 2025-12-02 Fatemeh Khashami

We study the experimental signatures of several states of a Bose-Einstein condensate of spin-1 atoms by quantum trajectory simulations of Stern-Gerlach experiments. The measurement process itself creates an apparent random alignment for the…

Soft Condensed Matter · Physics 2009-10-31 Juha Javanainen

In this paper, firstly considering that in separable states, the measurement of one particle has no effect on the measurement of the second particle, we show that Alice and Bob can find directions in which the results of their measurements…

Quantum Physics · Physics 2024-12-04 Mahmood Zeheiry

Unpredictability, or randomness, of the outcomes of measurements made on an entangled state can be certified provided that the statistics violate a Bell inequality. In the standard Bell scenario where each party performs a single…

Quantum Physics · Physics 2017-03-01 F. J. Curchod , M. Johansson , R. Augusiak , M. J. Hoban , P. Wittek , A. Acín

We study the projection on classical spins starting from quantum equilibria. We show Gibbsianness or quasi-locality of the resulting classical spin system for a class of gapped quantum systems at low temperatures including quantum ground…

Mathematical Physics · Physics 2015-05-12 Wojciech De Roeck , Christian Maes , Karel Netočný , Marius Schütz

Quantum entanglement is affected by unitary evolution, which spreads the entanglement through the whole system, and also by measurements, which usually tends to disentangle subsystems from the rest. Their competition has been known to…

Quantum Physics · Physics 2025-06-24 Haifeng Tang , Hong-Yi Wang , Zhong Wang , Xiao-Liang Qi

In classical physics, entropy quantifies the randomness of large systems, where the complete specification of the state, though possible in theory, is not possible in practice. In quantum physics, despite its inherently probabilistic…

Quantum Physics · Physics 2022-09-28 Davi Geiger , Zvi Kedem

W generalize the scheme for detection of qubit-environment entanglement to qudit-environment systems. This is of relevance for many-qubit systems and the quantification of the operation of quantum algorithms under the influence of external…

Quantum Physics · Physics 2025-04-01 Małgorzata Strzałka , Katarzyna Roszak

Reliable and well-characterized quantum resources are indispensable ingredients in quantum information processing. Typically, in a realistic characterization of these resources, apparatuses come with intrinsic uncertainties that can…

Many experiments in quantum information aim at creating multi-partite entangled states. Quantifying the amount of entanglement that was actually generated can, in principle, be accomplished using full-state tomography. This method requires…

Quantum Physics · Physics 2015-05-13 Harald Wunderlich , Martin B. Plenio

We present an approach to characterize genuine multiparticle entanglement using appropriate approximations in the space of quantum states. This leads to a criterion for entanglement which can easily be calculated using semidefinite…

Quantum Physics · Physics 2011-05-13 Bastian Jungnitsch , Tobias Moroder , Otfried Gühne

Entanglement is an important resource that allows quantum technologies to go beyond the classically possible. There are many ways quantum systems can be entangled, ranging from the archetypal two-qubit case to more exotic scenarios of…

Quantum Physics · Physics 2019-06-27 Nicolai Friis , Giuseppe Vitagliano , Mehul Malik , Marcus Huber

Non-classical correlations arising in complex quantum networks are attracting growing interest, both from a fundamental perspective and for potential applications in information processing. In particular, in an entanglement swapping…

Precision measurements are important across all fields of science. In particular, optical phase measurements can be used to measure distance, position, displacement, acceleration and optical path length. Quantum entanglement enables higher…

Quantum Physics · Physics 2009-11-13 Tomohisa Nagata , Ryo Okamoto , Jeremy L. O'Brien , Keiji Sasaki , Shigeki Takeuchi

Quantum metrology studies quantum strategies which enable us to outperform their classical counterparts. In this framework, the existence of perfect classical reference frames is usually assumed. However, such ideal reference frames might…

Quantum Physics · Physics 2015-03-17 Dominik Šafránek , Mehdi Ahmadi , Ivette Fuentes

There have been numerous studies of entanglement in spin systems. These have usually focussed on examining the entanglement between individual spins or determining whether the state of the system is completely separable. Here we present…

Quantum Physics · Physics 2015-05-19 Hongjun Zheng , Ho Trung Dung , Mark Hillery

The state overlap, quantified via $\tr[\rho \sigma]$, is a metric widely used to assess the closeness between two quantum states $\rho$ and $\sigma$. Although global state overlap alone does not directly capture entanglement properties, we…