Bipartite Bell Inequalities for Hyperentangled States

Cabello, Adán

doi:10.1103/physrevlett.97.140406

Cited by 22 publications

(13 citation statements)

References 30 publications

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“…Mermin showed that quantum mechanics violates Bell's equality by an amount that increases exponentially with the complexity of the system [71]. This violation was demonstrated using hyperentangled photon states [72,73].…”

Section: Orbital Angular Momentum Entanglementmentioning

confidence: 96%

Advances in optical angular momentum

Franke‐Arnold¹,

Allen

Padgett

2008

Laser & Photonics Reviews

857

574

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Some 16 years ago, Allen et al. [Phys. Rev. A 45, 8185 (1992)] recognised that laser beams which carried an angular momentum additional to photon spin, could be realized in the laboratory. Such beams have helical phase fronts and so have an azimuthal component to the Poynting vector, which results in angular momentum along the beam axis. This orbital angular momentum, very often combined with spin to make optical angular momentum, has given rise to many developments. These range from optical spanners for driving micro-machines to high dimensional quantum entanglement and new opportunities in quantum information processing. The concept of orbital angular momentum is now leading to new understanding of a wide range of phenomena, including fundamental processes in Bose-Einstein condensates, while the associated technologies have led to new applications in optical tweezing and microscopy.Orbital angular momentum phasefronts and interferogram

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Section: Orbital Angular Momentum Entanglementmentioning

confidence: 96%

Advances in optical angular momentum

Franke‐Arnold¹,

Allen

Padgett

2008

Laser & Photonics Reviews

857

574

View full text Add to dashboard Cite

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“…The cat states demonstrated here, together with other graph states technically feasible within our experimental method (see Supplementary Fig. S1), create a versatile testing ground for the study of non-locality 28 , multipartite entanglement and many quantum information protocols. Indeed, by taking advantage of the hyper-entanglement, it is now possible to reach some experimental regimes that were hardly accessible before, for instance, demonstrations of the robustness of anyonic braiding 29 and topological cluster-state encoding 30 that require manipulation of 7-10 qubits.…”

Section: H H H H H H H H Hmentioning

confidence: 98%

Experimental demonstration of a hyper-entangled ten-qubit Schrödinger cat state

et al. 2010

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Coherent manipulation of a large number of qubits and the generation of entangled states between them has been an important goal and benchmark in quantum information science, leading to various applications such as measurement-based quantum computing 1 and high-precision quantum metrology 2 . However, the experimental preparation of multiparticle entanglement remains challenging. Using atoms 3,4 , entangled states of up to eight qubits have been created, and up to six photons 5 have been entangled. Here, by exploiting both the photons' polarization and momentum degrees of freedom, we experimentally generate hyper-entangled six-, eight-and ten-qubit Schrödinger cat states with verified genuine multi-qubit entanglement. We also demonstrate super-resolving phase measurements enhanced by entanglement, with a precision to beat the standard quantum limit. Modifications of the experimental set-up would enable the generation of other graph states up to ten qubits. Our method offers a way of expanding the effective Hilbert space and should provide a versatile test-bed for various quantum applications.Control of single photonic qubits using linear optics has been an appealing approach to implementing quantum computing 6 . Experiments in recent years have demonstrated the photons' extremely long decoherence time 7 , fast clock speed 8 , a series of controlled quantum logic gates 9,10 and algorithms 8,11,12 and the generation of multiqubit entangled states 5 . A significant challenge, however, lies in making experimentally accessible sources of photonic multi-qubit states. This is because, on the one hand, the probabilistic nature of spontaneous parametric down-conversion 13 represents a bottleneck with regard to the attainable brightness and fidelity of multiphoton states based on it: manipulating seven photons or more seems an insurmountable challenge with present technology. On the other hand, triggered single-photon sources from independent quantum dots or other emitters still suffer from spectral and temporal distinguishability, which prevents up-scaling.There is, however, a way to experimentally control more effectively qubits, by exploiting hyper-entanglement 14 -the simultaneous entanglement in the multiple degrees of freedom that naturally exist for various physical systems. For instance, one can encode quantum information not only in the polarization of a single photon, but also in its spatial modes 15 Although the largest hyper-entangled state 15 realized so far has expanded the Hilbert space up to 144 dimensions, it is a product state of two-party entangled states and does not involve multipartite entanglement. Other schemes 20,21 for creating hyperentanglement have been limited by the technical problem of photonic subwavelength phase stability and seem infeasible to generate larger states than the two-photon four-qubit ones. Here, we will describe a method that overcomes these limitations, and the experimental generation of hyper-entangled six-, eight-and ten-qubit photonic Schrödinger cat states.The Schröding...

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“…The hyper-entangled states have been used to test "All-Versus-Nothing" (AVN) quantum nonlocality [11,12,15], and are shown to lead to an enhancing violation of local realism [16,17]. The states also enable to perform complete deterministic Bell state analysis [18] as demonstrated in [14,19].…”

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confidence: 99%

Experimental Realization of One-Way Quantum Computing with Two-Photon Four-Qubit Cluster States

et al. 2007

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We report an experimental realization of one-way quantum computing on a two-photon four-qubit cluster state. This is accomplished by developing a two-photon cluster state source entangled both in polarization and spatial modes. With this special source, we implemented a highly efficient Grover's search algorithm and high-fidelity two qubits quantum gates. Our experiment demonstrates that such cluster states could serve as an ideal source and a building block for rapid and precise optical quantum computation.PACS numbers: 03.67. Lx, 03.67.Mn, 42.50.Dv Highly entangled multipartite states, so-called cluster states, have recently raised enormous interest in quantum information processing (QIP). These sorts of states are crucial as a fundamental resource and a building block aimed at one-way universal quantum computing [1]. They are also essential elements for various quantum error correction codes and quantum communication protocols [2]. Moreover, the entanglements are shown to be robust against decoherence [3], and persistent against loss of qubits [1], and thus are exceptionally well suited for quantum computing and many tasks [1,2]. Considerable efforts have been made toward generating and characterizing cluster state in linear optics [4,5,6,7,8,9]. Recently the principal feasibility of a one-way quantum computing model has been experimentally demonstrated through 4-photon cluster states successfully [7,8,10].So far, preparing photonic cluster state still suffers from several serious limitations. Due to the probabilistic nature and Poissonian distribution of the parametric down-conversion process, the generation rate of 4-photon cluster states is quite low [5,6,7,8], and largely restricts speed of computing. Besides, the quality and fidelity of prepared cluster states are relatively low [6,7,8], which are difficult to be improved substantially. These disadvantages consequently impose great challenges of advancement even for few-qubit quantum computing.Fortunately, motivated by the progress that an important type of states termed hyper-entangled states have been experimentally generated [11,12,13,14], we have the possibility to produce a new type of cluster state (2-photon 4-qubit cluster state) with nearly perfect fidelity and high generation rate. The hyper-entangled states have been used to test "All-Versus-Nothing" (AVN) quantum nonlocality [11,12,15], and are shown to lead to an enhancing violation of local realism [16,17]. The states also enable to perform complete deterministic Bell state analysis [18] as demonstrated in [14,19].In this Letter we report an experimental realization of one-way quantum computing with such a 2-photon 4-qubit cluster state. The key idea is to develop and employ a bright source which produces a 2-photon state entangled both in polarization and spatial modes. We are thus able to implement the Grover's algorithm and quantum gates with excellent performances. The genuine four-partite entanglement and high fidelity of better than 88% are characterized by an optimal entanglement w...

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Bipartite Bell Inequalities for Hyperentangled States

Cited by 22 publications

References 30 publications

Advances in optical angular momentum

Advances in optical angular momentum

Experimental demonstration of a hyper-entangled ten-qubit Schrödinger cat state

Experimental Realization of One-Way Quantum Computing with Two-Photon Four-Qubit Cluster States

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