Experimental generation of an eight-photon Greenberger–Horne–Zeilinger state

Huang, Yun‐Feng; Liu, Bi-Heng; Liang, Peng; Li, Yuhu; Li, Li; Li, Chuan‐Feng; Guo, Guang‐Can

doi:10.1038/ncomms1556

Cited by 178 publications

(112 citation statements)

References 33 publications

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“…The creation and manipulation of entanglement, however, is a very demanding task, as it requires extremely precise quantum control and isolation from the environment. Thus, current experimental achievements are limited to rather small scale entangled systems [17][18][19] . On the other hand there is no proof that quantum entanglement is necessary for quantum information processing (QIP) that can outperform its classical counterpart.…”

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confidence: 99%

Quantum discord as resource for remote state preparation

et al. 2012

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Quantum entanglement is widely recognized as one of the key resources for the advantages of quantum information processing, including universal quantum computation 1 , reduction of communication complexity 2,3 or secret key distribution 4 . However, computational models have been discovered, which consume very little or no entanglement and still can efficiently solve certain problems thought to be classically intractable 5,6 . The existence of these models suggests that separable or weakly entangled states could be extremely useful tools for quantum information processing as they are much easier to prepare and control even in dissipative environments. It has been proposed that a requirement for useful quantum states is the generation of so-called quantum discord 7,8 , a measure of non-classical correlations that includes entanglement as a subset. Although a link between quantum discord and few quantum information tasks has been studied, its role in computation speed-up is still open and its operational interpretation remains restricted to only few somewhat contrived situations 9-12 . Here we show that quantum discord is the optimal resource for the remote quantum state preparation 13 , a variant of the quantum teleportation protocol 14 . Using photonic quantum systems, we explicitly show that the geometric measure of quantum discord 15 is related to the fidelity of this task, which provides an operational meaning. Moreover, we demonstrate that separable states with non-zero quantum discord can outperform entangled states. Therefore, the role of quantum discord might provide fundamental insights for resource-efficient quantum information processing.Introduction.-Quantum computation and quantum communication is believed to allow for information processing with an efficiency that cannot be achieved by any classical device. It is usually assumed that a key resource for this enhanced performance is quantum entanglement 16 . The creation and manipulation of entanglement, however, is a very demanding task, as it requires extremely precise quantum control and isolation from the environment. Thus, current experimental achievements are limited to rather small scale entangled systems [17][18][19] . On the other hand there is no proof that quantum entanglement is necessary for quantum information processing (QIP) that can outperform its classical counterpart. The investigation of QIP protocols that allow for significant enhancements in the efficiency of data processing by only using separable states is of high interest. Obviously, such states have the benefit of being easier to prepare and more robust against losses and experimental imperfections. In fact, there are quantum computational models based on mixed, separable states, most notably the so-called deterministic quantum computation with one qubit (DQC1) 5 , which has recently been demonstrated experimentally [20][21][22] . In this context, quantum discord has been proposed as the resource that can provide the enhancement for the computation 23,24 , but its relation to...

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confidence: 99%

Quantum discord as resource for remote state preparation

et al. 2012

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“…Recently, such multiphoton entanglement has been experimentally produced [34]. For example, GHZ entanglement up to eight photons [29,30] and cluster states up to eight photons [31] have been successfully generated. Several on-demand generation schemes were proposed theoretically [35,36] and are expected to be realized, e.g., based on semiconductor quantum dots [37].…”

Section: Fault-tolerant Quantum Computationmentioning

confidence: 99%

Nearly deterministic Bell measurement with multiphoton entanglement for efficient quantum-information processing

et al. 2015

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We present a detailed analysis of the Bell measurement scheme proposed in Lee et al. [Phys. Rev. Lett. 114, 113603 (2015)] based on a logical qubit using Greenberger-Horne-Zeilinger entanglement of photons. The success probability of the proposed Bell measurement can be made arbitrarily high using only linear optics as the number of photons in a logical qubit increases. We compare our scheme with all the other proposals, using single-photon qubits, coherent-state qubits, or hybrid qubits, suggested to enhance the efficiency of the Bell measurement. As a remarkable advantage, our scheme requires only photon on-off measurements, while photon number resolving detectors are necessary for all the other proposals. We find that the scheme based on coherent-state qubits shows the best performance with respect to the attained success probability in terms of the average number of photons used in the process, while our scheme outperforms the schemes using single-photon qubits. We finally show that efficient quantum communication and fault-tolerant quantum computation can be realized using our approach.

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“…With the rapid progress of experimental control techniques, the size of quantum systems with entanglement or coherence prepared in the laboratory has already grown to 8-10 qubits in photonic systems [7][8][9], 12 qubits in nuclear magnetic resonance (NMR) systems [10] and to even 14 qubits in ion traps [11]. Needless to say, performing state estimation tasks on such systems is tedious and time-consuming.…”

Section: Introductionmentioning

confidence: 99%

Optimal design of measurement settings for quantum-state-tomography experiments

Huang

Luo

et al. 2017

Phys. Rev. A

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Quantum state tomography is an indispensable but costly part of many quantum experiments. Typically, it requires measurements to be carried in a number of different settings on a fixed experimental setup. The collected data is often informationally overcomplete, with the amount of information redundancy depending on the particular set of measurement settings chosen. This raises a question about how should one optimally take data so that the number of measurement settings necessary can be reduced. Here, we cast this problem in terms of integer programming. For a given experimental setup, standard integer programming algorithms allow us to find the minimum set of readout operations that can realize a target tomographic task. We apply the method to certain basic and practical state tomographic problems in nuclear magnetic resonance experimental systems. The results show that, considerably less readout operations can be found using our technique than it was by using the previous greedy search strategy. Therefore, our method could be helpful for simplifying measurement schemes so as to minimize the experimental effort.

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Experimental generation of an eight-photon Greenberger–Horne–Zeilinger state

Cited by 178 publications

References 33 publications

Quantum discord as resource for remote state preparation

Quantum discord as resource for remote state preparation

Nearly deterministic Bell measurement with multiphoton entanglement for efficient quantum-information processing

Optimal design of measurement settings for quantum-state-tomography experiments

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