Phase-Controlled Collapse and Revival of Entanglement of Two Interacting Qubits

Malinovsky, Vladimir S.; Solá, Ignacio R.

doi:10.1103/physrevlett.96.050502

Cited by 37 publications

(28 citation statements)

References 29 publications

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“…To the extent that joint system information is a resource of substantial value in one or another practical application of qubit networks, this aspect of time-dependent entanglement will be important. At the same time it illuminates further the difficult fundamental challenge to understand the nature of coherence in multi-partite mixed states, particularly in its time-dependent behavior, which has recently come under examination in both continuous spaces [13,14,15] and discrete spaces (qubit pairs [16,17,18,19,20], finite spin chains and elementary lattices [21,22,23,24]), and decoherence dynamics in adiabatic entanglement [25], as well as in situations without relaxation [26] and in connection with direct entanglement observation [27]. These have all contributed to increased awareness of this domain.…”

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confidence: 99%

Quantum Open System Theory: Bipartite Aspects

2006

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We demonstrate in straightforward calculations that even under ideally weak noise the relaxation of bipartite open quantum systems contains elements not previously encountered in quantum noise physics. While additivity of decay rates is known to be generic for decoherence of a single system, we demonstrate that it breaks down for bipartite coherence of even the simplest composite systems.PACS numbers: 03.65. Yz, 03.65.Ud, 42.50.Lc In this note we will establish results that contradict the long-standing belief that additivity of coherence decay rates is a natural consequence of weak noises. This belief means that the relaxation rate of any system exposed to a collection of weak noises is the sum of the relaxation rates associated with the noises separately. Although implied in many textbook discussions, an actual proof of additivity may be difficult to locate. We supply here a proof of additivity for a single qubit coupled to two independent weak noises (here amplitude noise and phase noise), but our main message is the demonstration of violations of additivity in the case of entanglement decay when two or more qubits are involved. That is, we will show that a quantum system with the most elementary composite structure (e.g., simply made of two distinct parts) need not and generally does not exhibit relaxation-rate additivity even though the separate parts do. This result is purely quantum mechanical and extends our understanding of the power of quantum coherence in an unexpected direction.We now present an additivity proof that is quantum mechanical in order to eliminate from concern the possibility that quantum systems are intrinsically different from classical ones in their response to weak noise. We will consider ideal noise sources where "ideal" means that the noise is sufficiently weak and random that the noisesystem interaction is both reliably linear and without significant back action on the noise source. Each noise source can then be treated as a reservoir made of an infinite collection of random and very broadband harmonic oscillators at zero temperature.Of course the relaxing system need not be linear, so we choose the simplest nonlinear system, a qubit (two-level atom, spin one-half, etc.), for our example. The total Hamiltonian for a qubit coupled to two noise sources (two "environments") can be written as follows:(1) * Electronic address: ting@pas.rochester.edu † Electronic address: eberly@pas.rochester.edu where (with = 1)are the Hamiltonians of the qubit system and two local environments. As an example of the types of relaxation that will be relevant, we suppose the two environments couple in the one case longitudinally and in the other case transversely to the qubit. Thus we have for the interaction of the qubit with its two different noise sources:We naturally assume that the two noise sources are not cross-correlated, and in the ideal case under consideration they can be treated in the familiar Born-Markov limit. Thus we write the longitudinal and transverse selfcorrelation functions in the...

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confidence: 99%

Quantum Open System Theory: Bipartite Aspects

2006

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“…As shown in Ref. [27][28][29][30] although decoherence destroys the quantumness of the field, information of the initial field may be obtained via the reconstruction of quasiprobability distribution functions.…”

Section: The Wigner Functionmentioning

confidence: 99%

Anabiosis of phase distribution of a three-level atom

Abdel‐Aty

Azzeer

Abdalla

2010

Physica A: Statistical Mechanics and its Applications

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“…Rapid developments in quantum information and quantum computing have attracted considerable interest in the study of dynamical properties of entanglement and, consequently, some important ideas have been introduced, which include entanglement sudden death in the qubits coupling with a reservoir [1], collapse and revival of entanglement in two interacting qubits [2], and entanglement transfer from continuous variables to multiple qubits [3]. As an alternative with potential connections to actual experiments, other than the systems more usually employed in the field of entanglement and decoherence, the dynamical entanglement of two vibrational modes of a polyatomic molecule coupled by Coriolis interaction to overall molecular rotation is in the present work studied in terms of two negativities for various initial states and quantum numbers.…”

Section: Introductionmentioning

confidence: 99%