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Here we show that the concepts behind such terms as entanglement, qubits, quantum gates, quantum error corrections, unitary time evolution etc., which are usually ascribed to quantum systems, can be adequately realized on a set of coupled…

Quantum Physics · Physics 2023-12-04 Alexey V. Nenashev , Florian Gebhard , Klaus Meerholz , Sergei D. Baranovskii

We review some recent results on entanglement in the Quantum Spherical Model (QSM). The focus lays on the physical results rather than the mathematical details. Specifically, we study several entanglement-related quantities, such…

Statistical Mechanics · Physics 2023-06-28 Sascha Wald , Raul Arias , Vincenzo Alba

Entanglement is one of the fundamental properties of a quantum state and is a crucial differentiator between classical and quantum computation. There are many ways to define entanglement and its measure, depending on the problem or…

Quantum Physics · Physics 2025-01-07 Andrii Semenov , Niall Murphy , Simone Patscheider , Alessandra Bernardi , Elena Blokhina

The dynamics of the nuclear-spin quantum computer with large number (L=1000) of qubits is considered using a perturbation approach, based on approximate diagonalization of exponentially large sparse matrices. Small parameters are introduced…

Quantum Physics · Physics 2007-05-23 G. P. Berman , D. I. Kamenev , V. I. Tsifrinovich

Molecular spin clusters are mesoscopic systems whose structural and physical features can be tailored at the synthetic level. Besides, their quantum behavior is directly accessible in laboratory and their magnetic properties can be…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 F. Troiani , V. Bellini , A. Candini , G. Lorusso , M. Affronte

Quantum entanglement is a key ingredient for quantum information processing with capabilities beyond that of classical computation. We study the generation and role of entanglement in the dynamics of spin-1/2 models, both for the design of…

Quantum Physics · Physics 2024-06-11 Anupam Mitra

Previously, all known variants of the Quantum Satisfiability (QSAT) problem, i.e. deciding whether a $k$-local ($k$-body) Hamiltonian is frustration-free, could be classified as being either in $\mathsf{P}$; or complete for $\mathsf{NP}$,…

Quantum Physics · Physics 2025-06-10 Ricardo Rivera Cardoso , Alex Meiburg , Daniel Nagaj

Quantum computers are promising for simulations of chemical and physical systems, but the limited capabilities of today's quantum processors permit only small, and often approximate, simulations. Here we present a method, classical…

We use concurrence as an entanglement measure and experimentally demonstrate the entanglement classification of arbitrary three-qubit pure states on a nuclear magnetic resonance (NMR) quantum information processor. Computing the concurrence…

Quantum Physics · Physics 2018-10-29 Amandeep Singh , Kavita Dorai , Arvind

Quantum entanglement occurs not just in discrete systems such as spins, but also in the spatial wave functions of systems with more than one degree of freedom. It is easy to introduce students to entangled wave functions at an early stage,…

Physics Education · Physics 2017-11-22 Daniel V. Schroeder

Classically, for many computational problems one can conclude time lower bounds conditioned on the hardness of one or more of key problems: k-SAT, 3SUM and APSP. More recently, similar results have been derived in the quantum setting…

Computational Complexity · Computer Science 2022-07-25 Andris Ambainis , Harry Buhrman , Koen Leijnse , Subhasree Patro , Florian Speelman

The constrained synchronization problem (CSP) asks for a synchronizing word of a given input automaton contained in a regular set of constraints. It could be viewed as a special case of synchronization of a discrete event system under…

Formal Languages and Automata Theory · Computer Science 2021-08-03 Stefan Hoffmann

A scheme for generating an entangled state in a two spin-1/2 system by means of a spin-dependent potential scattering of another qubit is presented and analyzed in three dimensions. The entanglement is evaluated in terms of the concurrence…

Quantum Physics · Physics 2010-04-07 Yuichiro Hida , Hiromichi Nakazato , Kazuya Yuasa , Yasser Omar

We briefly review the physics of gate operations between quantum dot spin-qubits and analyze the dynamics of quantum entanglement in such processes. The indistinguishable character of the electrons whose spins realize the qubits gives rise…

Condensed Matter · Physics 2007-05-23 John Schliemann , Daniel Loss

The theory of Total Function NP (TFNP) and its subclasses says that, even if one is promised an efficiently verifiable proof exists for a problem, finding this proof can be intractable. Despite the success of the theory at showing…

Quantum Physics · Physics 2025-06-23 Marco Aldi , Sevag Gharibian , Dorian Rudolph

Quantum mechanics allows entanglement enhanced measurements to be performed, but loss remains an obstacle in constructing realistic quantum metrology schemes. However, recent work has revealed that entangled coherent states (ECSs) have the…

Quantum Physics · Physics 2015-06-18 P. A. Knott , W. J. Munro , J. A. Dunningham

This thesis focuses on the experimental creation and detection of a variety of quantum correlations using nuclear magnetic resonance hardware. Quantum entanglement, being most common and counter-intuitive, is one of the main type considered…

Quantum Physics · Physics 2019-05-16 Amandeep Singh

We define the algorithmic complexity of a quantum state relative to a given precision parameter, and give upper bounds for various examples of states. We also establish a connection between the entanglement of a quantum state and its…

Quantum Physics · Physics 2009-11-11 Caterina Mora , Hans Briegel

Classifying states as entangled or separable is a highly challenging task, while it is also one of the foundations of quantum information processing theory. This task is higly nontrivial even for relatively simple cases, such as two-qutrit…

Quantum Physics · Physics 2022-11-08 Marcin Wieśniak

Control over electron-spin states, such as coherent manipulation, filtering and measurement promises access to new technologies in conventional as well as in quantum computation and quantum communication. In this paper, we review recent…

Quantum Physics · Physics 2009-11-10 Shiro Kawabata