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We investigate the robustness of genuine multiparticle entanglement under decoherence. We consider different kinds of entangled three- and four-qubit states as well as random pure states. For amplitude damping noise, we find that the W-type…

Quantum Physics · Physics 2014-03-04 Mazhar Ali , Otfried Gühne

Detection of entanglement is an indispensable step to practical quantum computation and communication. Compared with the conventional entanglement witness method based on fidelity, we propose a flexible, machine learning assisted…

Quantum Physics · Physics 2022-11-11 Jue Xu , Qi Zhao

How entangled is a randomly chosen bipartite stabilizer state? We show that if the number of qubits each party holds is large the state will be close to maximally entangled with probability exponentially close to one. We provide a similar…

Quantum Physics · Physics 2007-05-23 Graeme Smith , Debbie Leung

We consider two measures of entanglement, the logarithmic negativity and the entanglement entropy, between regions of space in excited states of many-body systems formed by a finite number of particle excitations. In parts I and II of the…

Mathematical Physics · Physics 2019-08-20 Olalla A. Castro-Alvaredo , Cecilia De Fazio , Benjamin Doyon , István M. Szécsényi

Sharing genuine multipartite entanglement by considering collective use of copies of biseparable states, which are entangled across all bipartitions but lack genuine multipartite entanglement at the single-copy level, plays a central role…

Quantum Physics · Physics 2026-01-26 Swati Choudhary , Ujjwal Sen , Saronath Halder

This paper is to investigate the effects of quantum noises on entanglement localization by taking an example of reducing a three-qubit Greenberger-Horne-Zeilinger (GHZ) state to a two-qubit entangled state. We consider, respectively, two…

Quantum Physics · Physics 2015-01-19 Xin-Wen Wang , Shi-Qing Tang , Ji-Bing Yuan , Le-Man Kuang

We present multiparty entanglement purification protocols that are capable of purifying arbitrary graph states directly. We develop recurrence and breeding protocols and compare our methods with strategies based on bipartite entanglement…

Quantum Physics · Physics 2007-05-23 Caroline Kruszynska , Akimasa Miyake , Hans J. Briegel , Wolfgang Dür

We construct a simplex for multipartite qubit states of even number n of qubits, which has the same geometry concerning separability, mixedness, kind of entanglement, amount of entanglement and nonlocality as the bipartite qubit states. We…

Quantum Physics · Physics 2009-11-13 B. C. Hiesmayr , F. Hipp , M. Huber , Ph. Krammer , Ch. Spengler

We introduce magic measures to quantify the nonstabilizerness of multiqubit quantum gates and establish lower bounds on the $T$ count for fault-tolerant quantum computation. First, we introduce the stabilizer nullity of multi-qubit unitary,…

Quantum Physics · Physics 2023-03-21 Jiaqing Jiang , Xin Wang

It is known that if the quantum gates in a proposed quantum computer are so noisy that they are incapable of generating entanglement, then the device can be efficiently simulated classically. If the measurements and single particle…

Quantum Physics · Physics 2012-01-04 N. Ratanje , S. Virmani

We introduce a potential of multipartite entanglement for a system of n qubits, as the average over all balanced bipartitions of a bipartite entanglement measure, the purity. We study in detail its expression and look for its minimizers,…

Mathematical Physics · Physics 2010-01-30 Paolo Facchi

As quantum technology advances and the size of quantum computers grow, it becomes increasingly important to understand the extent of quality in the devices. As large-scale entanglement is a quantum resource crucial for achieving quantum…

Quantum Physics · Physics 2024-10-07 John F Kam , Haiyue Kang , Charles D Hill , Gary J Mooney , Lloyd C L Hollenberg

Whether noisy quantum devices without error correction can provide quantum advantage over classical computers is a critical issue of current quantum computation. In this work, the random quantum circuits, which are used as the paradigm…

Quantum Physics · Physics 2022-12-07 Meng Zhang , Chao Wang , Shaojun Dong , Hao Zhang , Yongjian Han , Lixin He

Highly entangled multipartite states such as k-uniform (k-UNI) and absolutely maximally entangled (AME) states serve as critical resources in quantum networking and other quantum information applications. However, there does not yet exist a…

Quantum Physics · Physics 2022-12-28 Zahra Raissi , Adam Burchardt , Edwin Barnes

Vast developments in quantum technology have enabled the preparation of quantum states with more than a dozen entangled qubits. The full characterization of such systems demands distinct constructions depending on their specific type and…

Verifying prepared quantum states is crucial for hybrid systems whose subsystems may have different local dimensions. We present a generalized stabilizer framework and associated test that apply to general multi-qudit states, including…

Quantum Physics · Physics 2025-11-25 Xiao-Dong Zhang , Bin-Bin Cai , Song Lin

We present a theoretical method to determine the multipartite entanglement between different partitions of multimode, fully or partially symmetric Gaussian states of continuous variable systems. For such states, we determine the exact…

Quantum Physics · Physics 2007-05-23 Gerardo Adesso , Alessio Serafini , Fabrizio Illuminati

The dependence of quantum algorithms on state fidelity is difficult to characterize analytically and is best explored experimentally as hardware scales and noisy simulations become intractable. While low fidelity states are often…

Quantum Physics · Physics 2025-05-09 Erika Lloyd , Alexandre Fleury , Marc P. Coons , James Brown , Maritza Hernandez

In quantum networks, eliminating connections between nodes is crucial to mitigate the effects of decoherence, often achieved by performing measurements on nodes that are idle, or vulnerable to noise. To characterize the entanglement content…

Quantum Physics · Physics 2025-08-08 Jithin G. Krishnan , Aditi Sen De , Amit Kumar Pal

Hypergraph states are multi-qubit states that form a subset of the locally maximally entangleable states and a generalization of the well--established notion of graph states. Mathematically, they can conveniently be described by a…

Quantum Physics · Physics 2014-08-11 O. Gühne , M. Cuquet , F. E. S. Steinhoff , T. Moroder , M. Rossi , D. Bruß , B. Kraus , C. Macchiavello