Multiuser quantum communication networks

Wójcik, Antoni; Łuczak, Tomasz; Kurzyński, Paweł; Grudka, Andrzej; Gdala, Tomasz; Bednarska, Małgorzata

doi:10.1103/physreva.75.022330

Cited by 85 publications

(102 citation statements)

References 23 publications

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“…Engineering the coupling between spins can improve the transport fidelity 4 , even allowing for perfect quantum state transport (QST), but it is difficult to achieve in experimental systems. Remarkable work 5,6 found relaxed coupling engineering requirements -however, even these proposals still required linear chains with nearest-neighbor couplings 7,8 or networks will all equal couplings 9 . These requirements remain too restrictive to allow an experimental implementation, since manufacturing highly regular networks is challenging with current technology [10][11][12][13] .…”

Section: Introductionmentioning

confidence: 99%

“…in crystals) with almost no fabrication requirements. In large networks, the end-spins are intrinsincally weakly coupled to the bulk network, allowing the use of a perturbative approach to describe the transport dynamics in this weak-coupling regime [5][6][7][8][9]14 . We identify two different scenarios for engineering perfect transport: the endspins could be set far off-resonance from the rest of the network -transport is then driven by a second-order process and hence is slow, but it requires no active control.…”

Section: Introductionmentioning

confidence: 99%

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Perfect quantum transport in arbitrary spin networks

Ajoy

Cappellaro

2013

Phys. Rev. B

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Spin chains have been proposed as wires to transport information between distributed registers in a quantum information processor. Unfortunately, the challenges in manufacturing linear chains with engineered couplings has hindered experimental implementations. Here we present strategies to achieve perfect quantum information transport in arbitrary spin networks. Our proposal is based on the weak coupling limit for pure state transport, where information is transferred between two end-spins that are only weakly coupled to the rest of the network. This regime allows disregarding the complex, internal dynamics of the bulk network and relying on virtual transitions or on the coupling to a single bulk eigenmode. We further introduce control methods capable of tuning the transport process and achieve perfect fidelity with limited resources, involving only manipulation of the end-qubits. These strategies could be thus applied not only to engineered systems with relaxed fabrication precision, but also to naturally occurring networks; specifically, we discuss the practical implementation of quantum state transfer between two separated nitrogen vacancy (NV) centers through a network of nitrogen substitutional impurities.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Perfect quantum transport in arbitrary spin networks

Ajoy

Cappellaro

2013

Phys. Rev. B

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“…Roughly * pascualox@gmail.com speaking, the resulting QST takes place in two distinct regimes: For very weak coupling, the bulk chain behaves merely like an information bus without being appreciably populated, and the probability amplitude of finding the excitation undergoes an effective Rabi oscillation between the sender and the receiver [16][17][18][19][20]; whereas, for nonperturbative end-point couplings, the relevant modes taking part in the quantum state dynamics reside mainly in the linear zone of the spectrum, thus, minimizing the effect of dispersion so that QST occurs in the so-called ballistic regime [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Routing quantum information in spin chains

et al. 2013

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Type of publicationArticle (peer-reviewed) Two different models are presented that allow for efficiently performing routing of a quantum state. Both cases involve an XX spin chain working as a data bus and additional spins that play the role of sender and receivers, one of which is selected to be the target of the quantum state transmission protocol via a coherent quantum coupling mechanism making use of local and/or global magnetic fields. Quantum routing is achieved in the first of the models considered by weakly coupling the sender and the receiver to the data bus. On the other hand, in the second model, local magnetic fields acting on additional spins located between the sender and receiver and the data bus allow us to perform high-fidelity routing.

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“…The second depends on the weak interaction of boundary spins to the remainders (bulk spins), making the bulk spins almost un-excited during the time evolution. The dynamics in the second method can be viewed as an effective Rabi oscillation between the boundary spins [15,[17][18][19]. In the other sort of schemes, such as modulating the Larmor frequencies on sites [20] or adding external potentials [21] to the spin chain, perfect state transfer can be obtained only for a fixed time.…”

Section: Introductionmentioning

confidence: 99%

Robust state transfer with high fidelity in spin-1/2 chains by Lyapunov control

Shi¹,

Zhao²

2015

Phys. Rev. A

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Based on the Lyapunov control, we present a scheme to realize state transfer with high fidelity by only modulating the boundary spins in a quantum spin-1/2 chain. Recall that the conventional transmission protocols aim at non-stationary state (or information) transfer from the first spin to the end spin at a fixed time. The present scheme possesses the following advantages. First, the scheme does not require precise manipulations of the control time. Second, it is robust against uncertainties in the initial states and fluctuations in the control fields. Third, the controls are exerted only on the boundary sites of the chain. It works for variable spin-1/2 chains with different periodic structures and has well scalability. The feasibility to replace the control fields by square pules is explored, which simplifies the realization in experiments.

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Multiuser quantum communication networks

Cited by 85 publications

References 23 publications

Perfect quantum transport in arbitrary spin networks

Perfect quantum transport in arbitrary spin networks

Routing quantum information in spin chains

Robust state transfer with high fidelity in spin-1/2 chains by Lyapunov control

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