Demonstration of Unconditional One-Way Quantum Computations

Ukai, Ryuji; Iwata, Noriaki; Shimokawa, Yoshihiko; Armstrong, Seiji; Politi, Alberto; Yoshikawa, Jun–ichi; Loock, Peter van; Furusawa, Akira

doi:10.1364/qels.2010.jthe24

Cited by 7 publications

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“…Provided enough squeezing is available to create the cluster states [138,196,206,207], this approach may also be used to realize the necessary squeezing corrections for nonlinear gate implementations, as discussed in the preceding section. The single-mode LUBO scheme was recently implemented experimentally [208,209]. More experiments on the creation of various CV cluster-type states and the offline implementation of CV C Z -type gates are presented in [210,211] and [26], respectively.…”

Section: Review Articlementioning

confidence: 99%

Optical hybrid approaches to quantum information

Loock

2011

Laser & Photonics Reviews

126

119

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This article reviews recent hybrid approaches to optical quantum information processing, in which both discrete and continuous degrees of freedom are exploited. There are well-known limitations to optical single-photon-based qubit and multi-photon-based qumode implementations of quantum communication and quantum computation, when the toolbox is restricted to the most practical set of linear operations and resources such as linear optics and Gaussian operations and states. The recent hybrid approaches aim at pushing the feasibility, the efficiencies, and the fidelities of the linear schemes to the limits, potentially adding weak or measurement-induced nonlinearities to the toolbox

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Section: Review Articlementioning

confidence: 99%

Optical hybrid approaches to quantum information

Loock

2011

Laser & Photonics Reviews

126

119

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“…In addition, balanced homodyne detection is available as a deterministic measurement. CV cluster states with four optical modes are generated and applied to unconditional one-way quantum computation in the frequency domain [16]. An ultra-large-scale CV cluster state containing > 10,000 modes is also generated by using a time-domain multiplexing method [17].…”

Section: Introductionmentioning

confidence: 99%

On-chip continuous-variable quantum entanglement

Masada

Furusawa

2016

Nanophotonics

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Entanglement is an essential feature of quantum theory and the core of the majority of quantum information science and technologies. Quantum computing is one of the most important fruits of quantum entanglement and requires not only a bipartite entangled state but also more complicated multipartite entanglement. In previous experimental works to demonstrate various entanglement-based quantum information processing, light has been extensively used. Experiments utilizing such a complicated state need highly complex optical circuits to propagate optical beams and a high level of spatial interference between different light beams to generate quantum entanglement or to efficiently perform balanced homodyne measurement. Current experiments have been performed in conventional free-space optics with large numbers of optical components and a relatively largesized optical setup. Therefore, they are limited in stability and scalability. Integrated photonics offer new tools and additional capabilities for manipulating light in quantum information technology. Owing to integrated waveguide circuits, it is possible to stabilize and miniaturize complex optical circuits and achieve high interference of light beams. The integrated circuits have been firstly developed for discrete-variable systems and then applied to continuous-variable systems. In this article, we review the currently developed scheme for generation and verification of continuous-variable quantum entanglement such as Einstein-Podolsky-Rosen beams using a photonic chip where waveguide circuits are integrated. This includes balanced homodyne measurement of a squeezed state of light. As a simple example, we also review an experiment for generating discrete-variable quantum entanglement using integrated waveguide circuits.

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“…105, 100503 (2010)], providing a rigorous validation of the conclusions of that work. The problem of identifying continuous-variable states with maximum resilience to entanglement damping in more general bosonic open-system dynamical evolutions, possibly including correlated noise and non-Markovian effects, remains open.Continuous-variable (CV) systems such as light modes and ultracold atomic ensembles [1] provide advantageous resources to achieve unconditional implementations of quantum information processing [2], ranging from teleportation protocols [3] to quantum key distribution [4] and one-way quantum computation [5]. Gaussian states and Gaussian operations, which represent respectively the most natural and easily controllable light states as well as the set of manipulations efficiently realizable by linear optics, have traditionally occupied a privileged role in all such implementations.…”

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confidence: 99%

“…Gaussian states and Gaussian operations, which represent respectively the most natural and easily controllable light states as well as the set of manipulations efficiently realizable by linear optics, have traditionally occupied a privileged role in all such implementations. Furthermore, by virtue of their mathematical simplicity compared to general states living in infinite-dimensional Hilbert spaces, bosonic Gaussian states have been and are the preferred testing grounds for a broad variety of investigations into the structure, nature, and dynamics of CV entanglement and quantum correlations [6].However, some prominent limitations of a Gaussian-only toolbox have been recently exposed in several contexts [7], stimulating vigorous theoretical and experimental research into the realm of non-Gaussian-state engineering and characterization [8], to assess and harness the potentially enhanced performance of de-Gaussified CV resources for quantum teleportation [9], entanglement distillation [10], parameter estimation [11], universal quantum computation [5,12], nonlocality tests [13], and so forth. Still, one of the most powerful features of Gaussian quantum states is their extremality [14] in the space of all CV states, which allows us to formulate valuable bounds on suitable entanglement measures and entropic degrees for a general non-Gaussian state , based on the corresponding (easier to compute) properties of the Gaussian state σ with the same first and second statistical moments as .…”

mentioning

confidence: 99%

“…Continuous-variable (CV) systems such as light modes and ultracold atomic ensembles [1] provide advantageous resources to achieve unconditional implementations of quantum information processing [2], ranging from teleportation protocols [3] to quantum key distribution [4] and one-way quantum computation [5]. Gaussian states and Gaussian operations, which represent respectively the most natural and easily controllable light states as well as the set of manipulations efficiently realizable by linear optics, have traditionally occupied a privileged role in all such implementations.…”

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Simple proof of the robustness of Gaussian entanglement in bosonic noisy channels

Adesso

2011

Phys. Rev. A

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The extremality of Gaussian states is exploited to show that Gaussian states are the most robust, among all possible bipartite continuous-variable states at fixed energy, against disentanglement due to noisy evolutions in Markovian Gaussian channels involving dissipation and thermal hopping. This proves a conjecture raised recently [M. Allegra, P. Giorda, and M. G. A. Paris, Phys. Rev. Lett. 105, 100503 (2010)], providing a rigorous validation of the conclusions of that work. The problem of identifying continuous-variable states with maximum resilience to entanglement damping in more general bosonic open-system dynamical evolutions, possibly including correlated noise and non-Markovian effects, remains open.Continuous-variable (CV) systems such as light modes and ultracold atomic ensembles [1] provide advantageous resources to achieve unconditional implementations of quantum information processing [2], ranging from teleportation protocols [3] to quantum key distribution [4] and one-way quantum computation [5]. Gaussian states and Gaussian operations, which represent respectively the most natural and easily controllable light states as well as the set of manipulations efficiently realizable by linear optics, have traditionally occupied a privileged role in all such implementations. Furthermore, by virtue of their mathematical simplicity compared to general states living in infinite-dimensional Hilbert spaces, bosonic Gaussian states have been and are the preferred testing grounds for a broad variety of investigations into the structure, nature, and dynamics of CV entanglement and quantum correlations [6].However, some prominent limitations of a Gaussian-only toolbox have been recently exposed in several contexts [7], stimulating vigorous theoretical and experimental research into the realm of non-Gaussian-state engineering and characterization [8], to assess and harness the potentially enhanced performance of de-Gaussified CV resources for quantum teleportation [9], entanglement distillation [10], parameter estimation [11], universal quantum computation [5,12], nonlocality tests [13], and so forth. Still, one of the most powerful features of Gaussian quantum states is their extremality [14] in the space of all CV states, which allows us to formulate valuable bounds on suitable entanglement measures and entropic degrees for a general non-Gaussian state , based on the corresponding (easier to compute) properties of the Gaussian state σ with the same first and second statistical moments as . This has important consequences for the security of CV quantum key distribution [15].The transmission of one-mode and multimode, possibly entangled, beams between distant locations, a basic necessity for the realization of a distributed quantum communication network [16], is unavoidably affected by various types of noise. While phase diffusion (dephasing) dampens the coherences in the Fock basis, transforming Gaussian states into non-Gaussian ones, the exposition to dissipative losses and thermal hopping yields an instance of a G...

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Demonstration of Unconditional One-Way Quantum Computations

Cited by 7 publications

References 0 publications

Optical hybrid approaches to quantum information

Optical hybrid approaches to quantum information

On-chip continuous-variable quantum entanglement

Simple proof of the robustness of Gaussian entanglement in bosonic noisy channels

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