Pretty good state transfer of entangled states through quantum spin chains

Sousa, Rúben; Omar, Yasser

doi:10.1088/1367-2630/16/12/123003

Cited by 35 publications

(47 citation statements)

References 44 publications

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“…(6), we can reduce the two-particle transfer amplitude to single-particle ones by means of the relation given in Ref. [37,46,47],…”

Section: A Rabi-like 2-qstmentioning

confidence: 99%

“…In many cases, the adopted strategies consist of extensions of 1-QST protocols and, as a consequence, the drawbacks and inconveniences they already presented for the 1-QST are, to some extent, even more amplified when it comes to the n-QST case. For example, the multirail scheme [33,34] requires the use of several quantum spin- 1 2 chains and a complex encoding and decoding scheme of the quantum states; employing linear chains made of spins of higher dimensionality reduces the number of chains to 1 but still requires a repeated measurement process with consecutive single site operations [35]; the fully engineered chain (eventually combined with the ballistic or Rabi-like mechanism), as well as the uniformly coupled chain with specific conditions on its length, needs conditional quantum gates to be performed on the recipients of the quantum state [36][37][38]. Therefore, simpler many qubits QST schemes would be quite appealing.…”

Section: Introductionmentioning

confidence: 99%

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Transfer of arbitrary two-qubit states via a spin chain

et al. 2015

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We investigate the fidelity of the quantum state transfer (QST) of two qubits by means of an arbitrary spin-1 2 network, on a lattice of any dimensionality. Under the assumptions that the network Hamiltonian preserves the magnetization and that a fully polarized initial state is taken for the lattice, we obtain a general formula for the average fidelity of the two qubits QST, linking it to the one-and two-particle transfer amplitudes of the spin excitations among the sites of the lattice. We then apply this formalism to a 1D spin chain with XX-Heisenberg type nearest-neighbour interactions adopting a protocol that is a generalization of the single qubit one proposed in Paganelli et al. [Phys. Rev. A 87, 062309 (2013)]. We find that a high-quality two qubit QST can be achieved provided one can control the local fields at sites near the sender and receiver. Under such conditions, we obtain an almost perfect transfer in a time that scales either linearly or, depending on the spin number, quadratically with the length of the chain.

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“…(6), we can reduce the two-particle transfer amplitude to single-particle ones by means of the relation given in Ref. [37,46,47],…”

Section: A Rabi-like 2-qstmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transfer of arbitrary two-qubit states via a spin chain

et al. 2015

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“…Hence, to realize perfect state transfer, spin chains with engineered couplings were proposed [14], and some modifications may also allow them to operate independently of their initialization [15] (see [16] for a detailed review on perfect state transfer). One may also get arbitrary perfect state transfer in uniform chains using dual-rail systems [17], d-level chains [18] or arrays of prime number of qubits [19,20]. In free fermionic systems, one gets arbitrarily high fidelities by engineering the two boundary couplings [21].…”

Section: Introductionmentioning

confidence: 99%

Measurement-assisted quantum communication in spin channels with dephasing

Bayat

Omar

2015

New J. Phys.

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We propose a protocol for countering the effects of dephasing in quantum state transfer over a noisy spin channel weakly coupled to the sender and receiver qubits. Our protocol, based on performing regular global measurements on the channel, significantly suppresses the nocuous environmental effects and offers much higher fidelities than the traditional no-measurement approach. Our proposal can also operate as a robust two-qubit entangling gate over distant spins. Our scheme counters any source of dephasing, including those for which the well established dynamical decoupling approach fails. Our protocol is probabilistic, given the intrinsic randomness in quantum measurements, but its success probability can be maximized by adequately tuning the rate of the measurements. A Bayat and Y Omar J J. ¢  In this limit, α diverges as J J ¢ and, by using a simple algebra, one can show that p J J Jt lim 1 4 sin 2 . 2 3 0 1 2 2 2 J J

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“…By using a full-engineering of the interactions one can obtain a perfect transmission to arbitrary distant sites [24,[56][57][58][59]. However, the full-engineering could be too demanding [60] in comparison with the level of fidelity required for the implementation of most quantum information processing tasks. In fact, for many practical purposes, an almost perfect transfer, achieved with a minimal engineering [61,62], provides a high enough fidelity without requiring a fine tuning of many parameters.…”

Section: A Efficiency Improvement Via Engineered Coupling Schemesmentioning

confidence: 99%

Toolbox for linear optics in a one-dimensional lattice via minimal control

2015

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Tight binding lattices offer a unique platform in which particles may be either static or mobile depending on the potential barrier between the sites. How to harness this mobility in a many-site lattice for useful operations is still an open question. We show how effective linear optics-like operations between arbitrary lattice sites can be implemented by a minimal local control which introduces a local impurity in the middle of the lattice. In particular we show how striking is the difference of the two possible correlations with and without the impurity. Our scheme enables the observation of the Hong-Ou-Mandel effect between distant wells without moving them next to each other with, e.g., tweezers. Moreover, we show that a tunable Mach-Zehnder interferometer is implemented adding a step-like potential, and we prove the robustness of our linear optics scheme to interparticle interactions.Linear optical networks are indispensable tools for both fundamental investigations of quantum interference phenomena and for practical applications. Beam splitters acting on two modes enable one to design simple two output interferometers such as the Mach-Zehnder and to observe bosonic behavior of two incident particles in the most striking way through the Hong-Ou-Mandel effect where the probability of one photon in each output is completely suppressed. The same types of effects form the bedrock of linear optical quantum computation [1,2], and of the boson sampling device [3][4][5][6][7]. The recent atomic realization of a controlled beam splitter in a double well potential [8] highlights the importance of atomic linear optics. This, and the recent unprecedented abilities to initialize and measure the positions of individual atoms [9][10][11][12], raise the intriguing question: can we use a many-site lattice for performing arbitrary linear-optics operations? Large lattices are indeed required for many applications, such as boson sampling where the complexity increases dramatically when the number sites is much larger than the number of particles.At a first glance, the realization of arbitrary operations seems improbable, as atoms on a multi-site lattice typically perform a "quantum walk" which is dispersive. This severely limits the observability even of basic linear-optics effects, such as bosonic bunching and/or fermionic anti-bunching, as the particles quickly spread out between multiple modes [9,10,[13][14][15][16][17][18][19]. In fact, such phenomena cannot be observed unless the particles are nearest neighbors or in the same site [18], even in the interacting case [9,10]. Obviously a new methodology is required in an atomic multi-site lattice for neat two mode demonstrations of such effects (as with two photons on a beam splitter [20] or matter waves [21]).Motivated as above we show (i) how to implement remote linear optics via the dynamics of trapped neutral atoms interacting via the Bose-Hubbard Hamiltonian; (ii) how to improve the efficiency of our scheme by introducing a minimal engineering of the couplings. Unlike ...

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Pretty good state transfer of entangled states through quantum spin chains

Cited by 35 publications

References 44 publications

Transfer of arbitrary two-qubit states via a spin chain

Transfer of arbitrary two-qubit states via a spin chain

Measurement-assisted quantum communication in spin channels with dephasing

Toolbox for linear optics in a one-dimensional lattice via minimal control

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