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We study the problem of optimal preparation of a bipartite entangled state, which remains entangled the longest time under action of local qubit noises. We show that for unital noises such a state is always maximally entangled, whereas for…

Quantum Physics · Physics 2018-01-23 Sergey N. Filippov , Vladimir V. Frizen , Daria V. Kolobova

The entanglement of two qubits, each defined as an effective two-level, spin 1/2 system, is investigated for the case that the qubits interact via a Heisenberg XY interaction and are subject to decoherence due to population relaxation and…

Quantum Physics · Physics 2007-05-23 Jin Wang , Herman Batelaan , Jeremy Podany , Anthony F. Starace

We study the dynamics of multipartite entanglement under the influence of decoherence. A suitable generalization of concurrence reveals distinct scaling of the entanglement decay rate of GHZ and W states, for various environments.

Quantum Physics · Physics 2009-11-10 André R. R. Carvalho , Florian Mintert , Andreas Buchleitner

Complexity in strongly correlated electron systems is analyzed by considering decoherence process between the localized state, |L> and the itinerant state, |I>. The coherent superposition state of a|I> + b|L> decoheres to the pointer states…

Strongly Correlated Electrons · Physics 2011-01-04 Byung Gyu Chae

For carrying out many quantum information protocols entanglement must be established in advance between two distant parties. Practically, inevitable interaction of entangled subsystems with their environments during distribution and storage…

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

We study a model of dephasing (decoherence) in a two-state quantum system (qubit) coupled to a bath of harmonic oscillators. An exact analytic solution for the reduced dynamics of a two-state system in this model has been obtained…

Quantum Physics · Physics 2015-05-28 V. G. Morozov , S. Mathey , G. Röpke

Creation of entangled states of quantum systems with low decoherence rates is a cornerstone in practical implementation of quantum computations. Processes of separate dephasing in each qubit in experimentally feasible systems is commonly…

Quantum Physics · Physics 2021-04-07 I. V. Vovcenko , V. Yu. Shishkov , E. S. Andrianov

Protecting entanglement from decoherence is a critical aspect of quantum information processsing. For many-body quantum systems evolving under decoherence, estimating multipartite entanglement is challenging. This challenge can be met up by…

Quantum Physics · Physics 2024-05-22 Chandrashekar Radhakrishnan , Sovik Roy , Ravikumar Chinnarasu , Md. Manirul Ali

Certain quantum states are well-known to be particularly fragile in the presence of decoherence, as illustrated by Schrodinger's famous gedanken cat experiment. It has been better appreciated more recently that quantum states can be…

We investigate the dynamics of coherence and entanglement of vibrating qubits. Firstly, we consider a single trapped ion qubit inside a perfect cavity and successively we use it to construct a bipartite system made of two of such…

Quantum Physics · Physics 2018-05-14 Ali Mortezapour , Ghasem Naeimi , Rosario Lo Franco

We consider spatially separated qubits coupled to a thermal bosonic field that causes pure dephasing. Our focus is on the entanglement of two Bell states which for vanishing separation are known as robust and fragile entangled states. The…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Roland Doll , Martijn Wubs , Peter Hanggi , Sigmund Kohler

By considering the decomposition of a generic two qubit density matrix presented by Wootters [W. K. Wootters, Phys. Rev. Lett. {\bf 80} 2245 (1998)], the robustness of entanglement for any mixed state of two qubit systems is obtained…

Quantum Physics · Physics 2007-05-23 S. J. Akhtarshenas , M. A. Jafarizadeh

We embarked upon the task of experimental protection of different classes of tripartite entangled states, namely the maximally entangled GHZ and W states and the ${\rm W \bar{W}}$ state, using dynamical decoupling. The states were created…

Quantum Physics · Physics 2018-02-07 Harpreet Singh , Arvind , Kavita Dorai

Quantum coherence, quantum entanglement and quantum nonlocality are important resources in quantum information precessing. However, decoherence happens when a quantum system interacts with the external environments. We study the dynamical…

Quantum Physics · Physics 2023-09-06 Tinggui Zhang , Hong Yang , Shao-Ming Fei

Quantum states inevitably decay with time into a probabilistic mixture of classical states, due to their interaction with the environment and measurement instrumentation. We present the first measurement of the decoherence dynamics of…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 H. Wang , M. Hofheinz , M. Ansmann , R. C. Bialczak , Erik Lucero , M. Neeley , A. D. O'Connell , D. Sank , M. Weides , J. Wenner , A. N. Cleland , John M. Martinis

In previous work, we have proposed an entanglement indicator for a general multiqubit state, which can be "learned" by a quantum system, acting as a neural network. The indicator can be used for a pure or a mixed state, and it need not be…

Quantum Physics · Physics 2017-02-07 E. C. Behrman , N. H. Nguyen , J. E. Steck , M. McCann

Quantum entanglement and decoherence are the two counterforces of many quantum technologies and protocols. For example, while quantum teleportation is fueled by a pair of maximally entangled resource qubits, it is vulnerable to decoherence.…

We analyze the robustness of decoherence-free (DF) subspace and subsystem in charge qubits, when difference from the collective decoherence measurement condition is large in the long time period, which is applicable for solid-state qubits…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Tetsufumi Tanamoto , Shinobu Fujita

We investigate the entanglement properties of pure quantum states describing $n$ qubits. We characterize all multipartite states which can be maximally entangled to local auxiliary systems using controlled operations. A state has this…

Quantum Physics · Physics 2013-05-29 C. Kruszynska , B. Kraus

Decoherence represents a major obstacle towards realizing reliable quantum technologies. Identifying states that can be uphold against decoherence by purely coherent means, i.e., {\it stabilizable states}, for which the dissipation-induced…

Quantum Physics · Physics 2023-04-26 Tomasz Linowski , Łukasz Rudnicki , Clemens Gneiting