Quantum cavities with alternating boundary conditions

Facchi, Paolo; Garnero, Giancarlo; Ligabò, Marilena

doi:10.1088/1751-8121/aaa9f9

Cited by 7 publications

(7 citation statements)

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“…[51, 52], a more general process, the quantum Zeno dynamics was raised, where the system can evolve away from its initial state under a multidimensional projection [53][54][55][56]. The quantum Zeno dynamics provides us with the possibility to significantly restrain the cavity decay in QIP tasks [57][58][59][60][61][62][63][64][65].…”

Section: Fig 1: (A) Diagrammatic Illustration Of the Cavity-atom-fibmentioning

confidence: 99%

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Noise-induced distributed entanglement in atom-cavity-fiber system

Li¹,

Shao²,

Wu³

2017

Opt. Express

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The distributed quantum computation plays an important role in large-scale quantum information processing. In the atom-cavity-fiber system, we put forward two efficient proposals to prepare the steady entanglement of two distant atoms with dissipation. The atomic spontaneous emission and the loss of fiber are exploited actively as powerful resources, while the effect of cavity decay is inhibited by quantum Zeno dynamics and quantumjump-based feedback control. These proposals do not require precisely tailored Rabi frequencies or coupling strength between cavity and fiber. Furthermore, we discuss the feasibility of extending the present schemes into the systems consisting of two atoms at the opposite ends of the n cavities connected by (n − 1) fibers, and the corresponding numerical simulation reveals that a high fidelity remains achievable with current experimental parameters. FIG. 1: (a) Diagrammatic illustration of the cavity-atom-fiber system and the atomic level for preparation of the Bell stateThe effective transitions of the reduced system.[51, 52], a more general process, the quantum Zeno dynamics was raised, where the system can evolve away from its initial state under a multidimensional projection [53][54][55][56]. The quantum Zeno dynamics provides us with the possibility to significantly restrain the cavity decay in QIP tasks [57][58][59][60][61][62][63][64][65]. On the other hand, the quantum feedback is usually applied in decoherence suppression, entanglement production, and entanglement protection [66][67][68][69][70][71][72][73][74]. This technology is based on immediately feeding back the measurement results to the quantum system of interest and then alter its subsequent dynamics. For instance, Mancini et al. controlled steady state Einstein-Podolsky-Rosen correlations for two bosonic modes interacting via parametric Hamiltonian by the quantum feedback [69]. Carvalho et al.proposed a direct feedback based on quantum-jump detection to achieve the maximal entangled states between two atoms in a cavity [70], and then they found that the quantum-jump-based feedback can protect highly entangled states against decoherence by comparing the effects of different control Hamiltonians and detection processes [71].In this paper, we propose two dissipative schemes to generate distant entangled Bell state and Knill-Laflamme-Milburn (KLM) state of two atoms with high fidelity, respectively, where two Λ atoms are trapped in two separated cavities connected by a fiber. We eliminate the unconcerned states by dispersive microwave fields, and inhibit the cavity decay by the quantum Zeno dynamics and the quantum-jump-based feedback control. The schemes have four distinctive features: (i) The target state is independent of the concrete initial states. (ii) The schemes are robust against the loss of photon, and the spontaneous emission of atoms and the decay of fibers are powerful resources to create target states. (iii) The atoms in different cavities are more convenient to be manipulated, and needn't precisely tailored...

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Section: Fig 1: (A) Diagrammatic Illustration Of the Cavity-atom-fibmentioning

confidence: 99%

“…For simplicity, we assume Ω 1 = Ω 2 = Ω in what follows. Referring to the quantum Zeno dynamics [55,56], we can write the H I Q as…”

Section: Introductionmentioning

confidence: 99%

Noise-induced distributed entanglement in atom-cavity-fiber system

Li¹,

Shao²,

Wu³

2017

Opt. Express

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“…In summary, we started with two commuting Hamiltonians H 0 and H 1 in (32), which are projected to P(H 0 ) and P(H 1 ) in (39), respectively, by the strong collective decoherence (33). As a consequence, the Ising chain (32) is changed into the Heisenberg chain (39), and our projected Hamiltonians P(H 0 ) and P(H 1 ) are not commutative anymore with each other. They generate the full algebra of J su(d J,N ) on the DFS's.…”

Section: Ising Chain Of N Qubits Under Collective Decoherencementioning

confidence: 99%

“…One is allowed to switch them on and off at will, but can induce only trivial dynamics on the system due to the commutativity. If one additionally performs frequent projective measurements described by a Hermitian projection P during the control, the system is confined to the subspace specified by the projection P due to the quantum Zeno effect (quantum Zeno subspace [30,31]), where the system evolves unitarily (quantum Zeno dynamics [30,32]) according to the projected counterparts of the control Hamiltonians, P H 1 P and P H 2 P . These projected Hamiltonians do not necessarily commute any more,…”

Section: Introductionmentioning

confidence: 99%

Universal control induced by noise

et al. 2016

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On the basis of the quantum Zeno effect, it has been recently shown [D. K. Burgarth, Nat. Commun. 5, 5173 (2014)2041-172310.1038/ncomms6173] that a strong-amplitude-damping process applied locally on a part of a quantum system can have a beneficial effect on the dynamics of the remaining part of the system. Quantum operations that cannot be implemented without the dissipation become achievable by the action of the strong dissipative process. Here we generalize this idea by identifying decoherence-free subspaces (DFSs) as the subspaces in which the dynamics becomes more complex. Applying methods from quantum control theory, we characterize the set of reachable operations within the DFSs. We provide three examples that become fully controllable within the DFSs while the control over the original Hilbert space in the absence of dissipation is trivial. In particular, we show that the (classical) Ising Hamiltonian is turned into a Heisenberg Hamiltonian by strong collective decoherence, which provides universal quantum computation within the DFSs. Moreover, we perform numerical gate optimization to study how the process fidelity scales with the noise strength. As a by-product, a subsystem fidelity that can be applied in other optimization problems for open quantum systems is developed

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“…The QCB paradigm has been used to show how to generate entangled states in composite systems by suitable modifications of the boundary conditions [30]. The relation of QCB and topology change has been explored in [39] and recently used to describe the physical properties of systems with moving walls ( [18], [19], [16], [17], [21]), but in spite of its intrinsic interest some basic issues such as the QCB controllability of simple systems has never been addressed.…”

Section: Introductionmentioning

confidence: 99%

Quantum Control at the Boundary

Balmaseda

Pérez-Pardo

2019

Springer Proceedings in Physics

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We introduce a scheme for controlling the state of a quantum system by manipulating its boundary conditions. This contrasts with the usual approach based on direct interactions with the system, that is, by adding interaction terms to the Hamiltonian of the system. We address this infinite-dimensional control problem, providing conditions to the existence of dynamics and approximate controllability for a family of quantum one-dimensional systems.

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Quantum cavities with alternating boundary conditions

Cited by 7 publications

References 32 publications

Noise-induced distributed entanglement in atom-cavity-fiber system

Noise-induced distributed entanglement in atom-cavity-fiber system

Universal control induced by noise

Quantum Control at the Boundary

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