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We propose a novel family of entanglement measures for time-separated subsystems. Our definitions are applicable to any quantum system, continuous or discrete. To illustrate their utility, we derive upper and lower bounds on time-separated…

Quantum Physics · Physics 2025-12-16 Alexey Milekhin , Zofia Adamska , John Preskill

Studying entanglement growth in quantum dynamics provides both insight into the underlying microscopic processes and information about the complexity of the quantum states, which is related to the efficiency of simulations on classical…

Quantum Gases · Physics 2013-09-23 J. Schachenmayer , B. P. Lanyon , C. F. Roos , A. J. Daley

We investigate theoretically the use of non-ideal ferromagnetic contacts as a mean to detect quantum entanglement of electron spins in transport experiments. We use a designated entanglement witness and find a minimal spin polarization of…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 Waldemar Kłobus , Andrzej Grudka , Andreas Baumgartner , Damian Tomaszewski , Christian Schönenberger , Jan Martinek

Rapidly growing capabilities of quantum simulators to probe quantum many-body phenomena require new methods to characterize increasingly complex states. We present a protocol that constrains quantum states by experimentally measured…

Quantum Physics · Physics 2025-09-22 Henry Froland , Torsten V. Zache , Robert Ott , Niklas Mueller

Quantum entanglement is the key to many applications like quantum key distribution, quantum teleportation, and quantum sensing. However, reliably generating quantum entanglement in macroscopic systems has proved to be a challenge. Here, we…

Entanglement does not correspond to any observable and its evaluation always corresponds to an estimation procedure where the amount of entanglement is inferred from the measurements of one or more proper observables. Here we address…

Quantum Physics · Physics 2009-11-13 Marco G. Genoni , Paolo Giorda , Matteo G. A. Paris

At present, there are many methods of quantum entanglement of particles with an electromagnetic field. Most methods have a low probability of quantum entanglement and not an exact theoretical apparatus based on an approximate solution of…

Quantum Physics · Physics 2017-09-15 Dmitry Makarov

Entanglement witnesses provide tools to detect entanglement in experimental situations without the need of having full tomographic knowledge about the state. If one estimates in an experiment an expectation value smaller than zero, one can…

Quantum Physics · Physics 2013-08-28 Jens Eisert , Fernando G. S. L. Brandao , Koenraad M. R. Audenaert

A critical requirement for diverse applications in Quantum Information Science is the capability to disseminate quantum resources over complex quantum networks. For example, the coherent distribution of entangled quantum states together…

Quantum Physics · Physics 2009-11-11 C. W. Chou , H. de Riedmatten , D. Felinto , S. V. Polyakov , S. J. van Enk , H. J. Kimble

The relation between entanglement entropy and the computational difficulty of classically simulating Quantum Mechanics is briefly reviewed. Matrix product states are proven to provide an efficient representation of one-dimensional quantum…

Quantum Physics · Physics 2008-11-26 Jose I. Latorre

In the last years several estimation strategies have been formulated to determine the value of an unknown parameter in the most precise way, taking into account the presence of noise. These strategies typically rely on the use of quantum…

Quantum Physics · Physics 2021-08-31 Andrea Smirne , Andreas Lemmer , Martin B. Plenio , Susana F. Huelga

Quantum entanglement is considered, by and large, to be a very delicate and non-robust phenomenon that is very hard to maintain in the presence of noise, or non-zero temperatures. In recent years however, and motivated, in part, by a quest…

Quantum Physics · Physics 2017-02-27 Lior Eldar

Detecting entanglement in multipartite quantum states is an inherently probabilistic process, typically with a few measured samples. The level of confidence in entanglement detection quantifies the scheme's validity via the probability that…

We study entanglement between quantum states of multi level spin system of a single particle considering a nucleus with spin 3/2 in both the internal electric field gradient and the external magnetic field. It was shown that entanglement is…

Quantum Physics · Physics 2010-06-21 G. B. Furman , V. M. Meerovich , V. L. Sokolovsky

We develop a framework and give an example for situations where two distinct Hamiltonians living in the same Hilbert space can be used to simulate the same physics. As an example of an analog simulation, we first discuss how one can…

Quantum Physics · Physics 2021-04-28 Karol Gietka , Ayaka Usui , Jianqiao Deng , Thomas Busch

Quantum state tomography serves as a key tool for identifying quantum states generated in quantum computers and simulators, typically involving local operations on individual particles or qubits to enable independent measurements. However,…

Quantum Gases · Physics 2026-03-26 Giacomo Marmorini , Takeshi Fukuhara , Daisuke Yamamoto

Simulating computationally intractable many-body problems on a quantum simulator holds great potential to deliver insights into physical, chemical, and biological systems. While the implementation of Hamiltonian dynamics within a quantum…

Quantum Physics · Physics 2020-03-27 Meghana Raghunandan , Fabian Wolf , Christian Ospelkaus , Piet O. Schmidt , Hendrik Weimer

Spin squeezing is a form of entanglement that reshapes the quantum projection noise to improve measurement precision. Here, we provide numerical and analytic evidence for the following conjecture: any Hamiltonian exhibiting finite…

Entanglement witnesses are invaluable for efficient quantum entanglement certification without the need for expensive quantum state tomography. Yet, standard entanglement witnessing requires multiple measurements and its bounds can be…

Quantum Physics · Physics 2017-03-22 Farid Shahandeh , Martin Ringbauer , Juan C. Loredo , Timothy C. Ralph

We perform a quantum simulation of the Ising model with a transverse field using a collection of three trapped atomic ion spins. By adiabatically manipulating the Hamiltonian, we directly probe the ground state for a wide range of fields…

Quantum Physics · Physics 2011-12-15 E. E. Edwards , S. Korenblit , K. Kim , R. Islam , M. -S. Chang , J. K. Freericks , G. -D. Lin , L. -M. Duan , C. Monroe