Generation of Werner states and preservation of entanglement in a noisy environment

Jakóbczyk, Lech; Jamróz, Anna

doi:10.1016/j.physleta.2005.08.033

Cited by 10 publications

(11 citation statements)

References 21 publications

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“…As a measure of entanglement between two parties such as the transmon qubits, concurrence is a convenient choice and can be computed directly from the density matrix of the system [54]. The concurrence formula for the half-parity setup is greatly simplified because of the suppression of most matrix elements, resulting in an X-shape density matrix, of which the concurrence is calculated from [54,55] CðtÞ ¼ 2 max f0; x 5 ðtÞ − ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi…”

Section: Concurrence Trajectories and Their Distributionmentioning

confidence: 99%

Quantum Trajectories and Their Statistics for Remotely Entangled Quantum Bits

et al. 2016

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We experimentally and theoretically investigate the quantum trajectories of jointly monitored transmon qubits embedded in spatially separated microwave cavities. Using nearly quantum-noise-limited superconducting amplifiers and an optimized setup to reduce signal loss between cavities, we can efficiently track measurement-induced entanglement generation as a continuous process for single realizations of the experiment. The quantum trajectories of transmon qubits naturally split into low and high entanglement classes. The distribution of concurrence is found at any given time, and we explore the dynamics of entanglement creation in the state space. The distribution exhibits a sharp cutoff in the high concurrence limit, defining a maximal concurrence boundary. The most-likely paths of the qubits' trajectories are also investigated, resulting in three probable paths, gradually projecting the system to two even subspaces and an odd subspace, conforming to a "half-parity" measurement. We also investigate the most-likely time for the individual trajectories to reach their most entangled state, and we find that there are two solutions for the local maximum, corresponding to the low and high entanglement routes. The theoretical predictions show excellent agreement with the experimental entangled-qubit trajectory data.

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Section: Concurrence Trajectories and Their Distributionmentioning

confidence: 99%

Quantum Trajectories and Their Statistics for Remotely Entangled Quantum Bits

et al. 2016

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“…Observe also that when T → ∞, C as (z) → z, so in the reservoir at infinite temperature the initial entanglement is exactly preserved [20].…”

Section: B Entangled Initial Statesmentioning

confidence: 93%

“…where the mixing probability p depends on the fidelity of the initial state and temperature of the reservoir : Notice that in the limit β → 0 (or T → ∞) we obtain the standard Werner state [17], hence the dynamical generation of such states occurs due to the interaction with the environment with maximal noise [20]. The entanglement properties of the asymptotic state will be discussed in the next section.…”

Section: Strongly Correlated Qubits and Nontrivial Asymptotic Stmentioning

confidence: 98%

Generation of Werner-like stationary states of two qubits in a thermal reservoir

Jakóbczyk

2009

J. Phys. B: At. Mol. Opt. Phys.

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“…The time evolution of entanglement for a system of two qubits, or two two-level atoms, has been widely studied in recent years. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] For more information and extensive literature on the subject see the review article, Ref. 20.…”

Section: Introductionmentioning

confidence: 99%

Sudden death and sudden birth of entanglement

Tanaś

2010

Quantum Dynamics and Information

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We compare the evolution of entanglement for a system of two two-level atoms interacting with (i) a common reservoir being in the vacuum state and (ii) a common thermal reservoir at non-zero temperature. The Markovian master equation is used to describe the evolution of entanglement which is quantified by concurrence. Phenomena of sudden death, revival, and sudden birth of entanglement are discussed. It is shown that when the atoms behave collectively and the reservoir is the vacuum, the entanglement evolution exhibits quite a rich structure. For thermal reservoir with non-zero mean number of photons this structure is gradually degraded as the temperature of the reservoir increases. For thermal reservoir the phenomenon of sudden death of entanglement becomes a standard behavior, and no asymptotic evolution can be observed. As the temperature of the reservoir increases the sudden birth of entanglement, which is a signature of collective behavior of the atoms in the vacuum, gradually disappears. The results are illustrated graphically for a number of initial states of the two-atom system.

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Generation of Werner states and preservation of entanglement in a noisy environment

Cited by 10 publications

References 21 publications

Quantum Trajectories and Their Statistics for Remotely Entangled Quantum Bits

Quantum Trajectories and Their Statistics for Remotely Entangled Quantum Bits

Generation of Werner-like stationary states of two qubits in a thermal reservoir

Sudden death and sudden birth of entanglement

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