Entanglement dynamics in three-qubit<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>X</mml:mi></mml:mrow></mml:math>states

Weinstein, Yaakov S.

doi:10.1103/physreva.82.032326

Cited by 40 publications

(50 citation statements)

References 31 publications

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“…quantum correlations eventually decohere, as expected for three subsystems subject to local dissipation such as dephasing or depolarizing channels [34]. This is in marked contrast to two-qubit baths where the antidiagonal components ofρ E that appear in Eqs.…”

Section: General Case: Master Equations For N-qubit Environmentsmentioning

confidence: 80%

“…5(b), are the key ingredient for entangling the systems. This highlights the significance of the two-qubit X-state environments (described by a state matrix in which only diagonal and antidiagonal entries are nonzero) [34,35]. Daǧ et al [23] encountered a similar result-they found that antidiagonal coherences in n = 3 qubit baths do not contribute to squeezing or displacement of a single cavity mode.…”

Section: General Case: Master Equations For N-qubit Environmentsmentioning

confidence: 80%

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Quantum master equations for entangled qubit environments

et al. 2018

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We study the Markovian dynamics of a collection of n quantum systems coupled to an irreversible environmental channel consisting of a stream of n entangled qubits. Within the framework of repeated quantum interactions, we derive the master equation that describes the dynamics of the composite quantum system. We investigate the evolution of the joint system for two-qubit environments and find that (1) the presence of antidiagonal coherences (in the local basis) in the environment is a necessary condition for entangling two remote systems, and (2) that maximally entangled two-qubit baths are an exceptional point without a unique steady state. For the general case of n-qubit environments we show that coherences in maximally entangled baths (when expressed in the local energy basis), do not affect the system evolution in the weak coupling regime.

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Section: General Case: Master Equations For N-qubit Environmentsmentioning

confidence: 80%

Section: General Case: Master Equations For N-qubit Environmentsmentioning

confidence: 80%

Quantum master equations for entangled qubit environments

et al. 2018

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“…Those states arise naturally in quantum information theory in various aspects. See [1,26,29,30,31,32] for example. Notable examples include Greenberger-Horne-Zeilinger diagonal states, which are mixtures of GHZ states with noises.…”

Section: Introductionmentioning

confidence: 99%

The role of phases in detecting three-qubit entanglement

Han

Kye

2017

Journal of Mathematical Physics

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Abstract. We propose separability criteria for three-qubit states in terms of diagonal and anti-diagonal entries to detect entanglement with positive partial transposes. We report that the phases, that is, the angular parts of anti-diagonal entries, play a crucial role in determining whether a given three-qubit state is separable or entangled, and they must obey even an identity for separability in some cases. These criteria are strong enough to detect PPT (positive partial transpose) entanglement with nonzero volume. In several cases when all the entries are zero except for diagonal and anti-diagonal entries, we characterize separability using phases. These include the cases when anti-diagonal entries of such states share a common magnitude, and when ranks are less than or equal to six. We also compute the lengths of rank six cases, and find three-qubit separable states with lengths 8 whose maximum ranks of partial transposes are 7.

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“…Alluding to the pattern of nonzero matrix elements, states of this structure are known as X states (here, there are some additional zeros). X states have been widely studied [70][71][72][73][74][75][76] with respect to entanglement and other quantum properties, in particular a subset of these states, which is called GHZ-diagonal [77]. Despite their simple structure, states of this form yield a rich pattern in the map of entanglement classes as we will see in the following.…”

Section: Map Of Entanglement Classesmentioning

confidence: 99%

Generating entangled quantum microwaves in a Josephson-photonics device

2017

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When connecting a voltage-biased Josephson junction in series to several microwave cavities, a Cooper-pair current across the junction gives rise to a continuous emission of strongly correlated photons into the cavity modes. Tuning the bias voltage to the resonance where a single Cooper pair provides the energy to create an additional photon in each of the cavities, we demonstrate the entangling nature of these creation processes by simple witnesses in terms of experimentally accessible observables. To characterize the entanglement properties of the such created quantum states of light to the fullest possible extent, we then proceed to more elaborate entanglement criteria based on the knowledge of the full density matrix and provide a detailed study of bi-and multipartite entanglement. In particular, we illustrate how due to the relatively simple design of these circuits changes of experimental parameters allow one to access a wide variety of entangled states differing, e.g., in the number of entangled parties or the dimension of state space. Such devices, besides their promising potential to act as a highly versatile source of entangled quantum microwaves, may thus represent an excellent natural testbed for classification and quantification schemes developed in quantum information theory.properly choosing an elaborate pulse scheme, in principle, any entangled state could be created, it is typically a maximally entangled or another simple pure entangled state which such experiments aim for.The creation of multipartite or other more complex entangled states requires increasingly complex pulse schemes. These are reachable in such systems since one can build on the immense research effort (and the resulting amazing progress in performance and control) which has been spent on these standard circuitquantum-electrodynamics (QED) setups as part of the larger quest for universal quantum computing. Here we argue, however, that combining two key elements of circuit-QED setups, namely, Josephson junctions and microwave cavities, in a much simpler, less demanding device can offer an alternative, fully tunable and versatile entanglement-generating source.Recently developed Josephson-photonics devices [21][22][23][24], which already demonstrated their potential as a source of nonclassical microwave light [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39], seem to be logical candidates for this task. In fact, the next generation of setups currently being under fabrication is designed to explore bipartite photon creation processes. The goals of the present work are thus twofold: to make detailed and quantitative predictions about entanglement properties of this new class of superconducting devices and to give instructions how to vary and design experimental parameters accordingly. In this respect, the simple bipartite case is only the first step. As we will show, Josephson-photonics architectures allow one by comparatively simple changes of experimental parameters to also access multipartite situations, the characteriz...

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Entanglement dynamics in three-qubitXstates

Cited by 40 publications

References 31 publications

Quantum master equations for entangled qubit environments

Quantum master equations for entangled qubit environments

The role of phases in detecting three-qubit entanglement

Generating entangled quantum microwaves in a Josephson-photonics device

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