Optimal entanglement generation for efficient hybrid quantum repeaters

Azuma, Koji; Sota, Naoya; Namiki, Ryo; Özdemir, Şahin Kaya; Yamamoto, Takashi; Koashi, Masato; Imoto, Nobuyuki

doi:10.1103/physreva.80.060303

Cited by 28 publications

(64 citation statements)

References 23 publications

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“…(47) is possible, completely eliminating bit-flip errors [162]. The remaining phase-flip errors caused by photon losses may be minimized and thus fidelities for given success probabilities maximized through optimal USD [162], attainable, for instance, by means of photon number resolving detectors and using two probe pulses [225]. Other non-Gaussian POVMs such as CSSstate projections can be considered [226] as well as homodyne detections on squeezed-state instead of coherent-state qumode ancillae [227].…”

Section: Figure 31mentioning

confidence: 99%

Optical hybrid approaches to quantum information

Loock

2011

Laser & Photonics Reviews

116

115

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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: Figure 31mentioning

confidence: 99%

Optical hybrid approaches to quantum information

Loock

2011

Laser & Photonics Reviews

116

115

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“…Our question is immediately relevant to the field of quantum information, since assessing the deviation from the identity channel, i.e., the ideal information transmitter, is the principal requirement to implementing large-scale quantum communication. The need for an efficient characterization of dissipation in continuous variable systems is becoming a requisite for a number of quantum-information tasks, such as quantum repeaters [1,2] or quantum memories [3][4][5], among others. The burden of dissipation is also hindering advances in cavity QED [6,7] and superconducting quantum circuits [8].…”

Section: Introductionmentioning

confidence: 99%

Measurement of damping and temperature: Precision bounds in Gaussian dissipative channels

Monràs

Illuminati

2011

Phys. Rev. A

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We present a comprehensive analysis of the performance of different classes of Gaussian states in the estimation of Gaussian phase-insensitive dissipative channels. In particular, we investigate the optimal estimation of the damping constant and reservoir temperature. We show that, for two-mode squeezed vacuum probe states, the quantum-limited accuracy of both parameters can be achieved simultaneously. Moreover, we show that for both parameters two-mode squeezed vacuum states are more efficient than coherent, thermal, or single-mode squeezed states. This suggests that at high-energy regimes, two-mode squeezed vacuum states are optimal within the Gaussian setup. This optimality result indicates a stronger form of compatibility for the estimation of the two parameters. Indeed, not only the minimum variance can be achieved at fixed probe states, but also the optimal state is common to both parameters. Additionally, we explore numerically the performance of non-Gaussian states for particular parameter values to find that maximally entangled states within d-dimensional cutoff subspaces (d⩽6) perform better than any randomly sampled states with similar energy. However, we also find that states with very similar performance and energy exist with much less entanglement than the maximally entangled ones

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“…Nonetheless, as long as Alice and Bob are not too far away from each other, say over a couple of hundred kilometres, the intermediate nodes would not be necessary, because the current point-to-point quantum communication has already been very efficient as well as ready for practical use6. Besides, in terms of the communication efficiency for the distance, known optical schemes278910111213 for the point-to-point links are shown to have no scaling gap with an upper bound on the quantum capacity and the private capacity of the lossy optical channel, called Takeoka–Guha–Wilde (TGW) bound1415.…”

mentioning

confidence: 99%

“…Despite the differences in advantage and disadvantage between the TGW bound and the PLOB bound, perhaps most importantly in practice, both of them show that there remains not much room to improve known optical quantum communication schemes278910111213 for point-to-point links further. Unfortunately, the point-to-point communication is not efficient enough to achieve the quantum internet.…”

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confidence: 99%

Fundamental rate-loss trade-off for the quantum internet

2016

Self Cite

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The quantum internet holds promise for achieving quantum communication—such as quantum teleportation and quantum key distribution (QKD)—freely between any clients all over the globe, as well as for the simulation of the evolution of quantum many-body systems. The most primitive function of the quantum internet is to provide quantum entanglement or a secret key to two points efficiently, by using intermediate nodes connected by optical channels with each other. Here we derive a fundamental rate-loss trade-off for a quantum internet protocol, by generalizing the Takeoka–Guha–Wilde bound to be applicable to any network topology. This trade-off has essentially no scaling gap with the quantum communication efficiencies of protocols known to be indispensable to long-distance quantum communication, such as intercity QKD and quantum repeaters. Our result—putting a practical but general limitation on the quantum internet—enables us to grasp the potential of the future quantum internet.

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Optimal entanglement generation for efficient hybrid quantum repeaters

Cited by 28 publications

References 23 publications

Optical hybrid approaches to quantum information

Optical hybrid approaches to quantum information

Measurement of damping and temperature: Precision bounds in Gaussian dissipative channels

Fundamental rate-loss trade-off for the quantum internet

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