Experimental one-step deterministic polarization entanglement purification

Huang, Cen-Xiao; Hu, Xiaomin; Liu, Bi-Heng; Zhou, Lan; Sheng, Yu‐Bo; Li, Chuan‐Feng; Guo, Guang‐Can

doi:10.1016/j.scib.2021.12.018

Cited by 39 publications

(12 citation statements)

References 47 publications

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“…Furthermore, the logical qubits constructed by physical qubits in the encoded space provide a possible method to accomplish many quantum information tasks. For example, the entanglement purification, which is able to distill the high-fidelity entangled states from the noisy low-quality entangled source 51 – 53 , could be achieved with the logic-qubit entanglement against bit-flip and phase-flip errors 54 , 55 . Another illustration is the long-distance quantum communication with logical qubits in which the fault-tolerant Calderbank–Shor–Steane encoding method is exploited to implement the ultrafast quantum communication across long distances 56 – 58 .…”

Section: Discussionmentioning

confidence: 99%

Optical demonstration of quantum fault-tolerant threshold

Sun¹,

Xu²,

Xu³

et al. 2022

Light Sci Appl

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A major challenge in practical quantum computation is the ineludible errors caused by the interaction of quantum systems with their environment. Fault-tolerant schemes, in which logical qubits are encoded by several physical qubits, enable to the output of a higher probability of correct logical qubits under the presence of errors. However, strict requirements to encode qubits and operators render the implementation of a full fault-tolerant computation challenging even for the achievable noisy intermediate-scale quantum technology. Especially the threshold for fault-tolerant computation still lacks experimental verification. Here, based on an all-optical setup, we experimentally demonstrate the existence of the threshold for the fault-tolerant protocol. Four physical qubits are represented as the spatial modes of two entangled photons, which are used to encode two logical qubits. The experimental results clearly show that when the error rate is below the threshold, the probability of correct output in the circuit, formed with fault-tolerant gates, is higher than that in the corresponding non-encoded circuit. In contrast, when the error rate is above the threshold, no advantage is observed in the fault-tolerant implementation. The developed high-accuracy optical system may provide a reliable platform to investigate error propagation in more complex circuits with fault-tolerant gates.

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Section: Discussionmentioning

confidence: 99%

Optical demonstration of quantum fault-tolerant threshold

Sun¹,

Xu²,

Xu³

et al. 2022

Light Sci Appl

Self Cite

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“…f p out > f p in and f p out > f s in . In some special cases, such as strong robustness of spatial or time DoFs in experiments [25,26], the entanglement of this robust DoF is nearly pure state, e.g. f s = 1 in Eq.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…The first photonic EP protocol which makes use of ancillary DoF is based on selecting the path of entangled pairs [10] and subsequently performed in experiment [19]. Besides, one can design the EP protocol with only one pair of photons with multi-DoF hyperentanglement [11][12][13][14][15][16][23][24][25][26], e.g. Simon-Pan [11] and HHSZ+ [23] protocols.…”

Section: Introductionmentioning

confidence: 99%

Variational quantum circuit learning of entanglement purification in multi-degree-of-freedom

Zhang¹,

Xu²,

Zhang³

et al. 2022

Preprint

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Quantum entanglement purification (EP) is a crucial technique for promising the effective function of entanglement channel in noisy large-scale quantum network. The previous EP protocols lack of a general circuit framework and become complicated to design in high-dimensional cases. In this paper, we propose a variational quantum circuit framework and demonstrate its feasibility of learning optimal protocols of EP in multi-degreeof-freedom (DoF). By innovatively introducing the additional circuit lines for representing the ancillary DoFs, e.g. space and time, the parameterized quantum circuit can effectively simulate the scalable EP process. As examples, well-known protocols in linear optics including PSBZ, HHSZ+ and etc., are learnt successfully with high fidelities and the alternative equivalent operations are discovered in low-depth quantum circuit. Our work pays the way for exploring the EP protocols with multi-DoF by quantum machine learning.

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“…In particular, some interesting schemes for implementing nonlocal quantum operations between two different nodes have been proposed based on the sharing of entangled photon pairs, which act as the quantum channel for the teleportation of quantum gates [25][26][27][28][29]. In contrast to other schemes which rely on the transmission of a single photon through an optical channel to transmit interaction between two separate nodes, an attractive advantage of teleportation-based architectures is that the environmental noise and photon loss could be well overcome via entanglement purification together with quantum repeaters [30][31][32][33][34][35][36]. Moreover, photon possesses multiple degrees of freedom (DOFs) for encoding, such as polarization, spatial mode, frequency, time bin, and orbit angular momentum.…”

Section: Introductionmentioning

confidence: 99%

Scheme for implementing nonlocal high-fidelity quantum controlled-not gates on quantum-dot-confined electron spins using optical microcavities and photonic hyperentanglement

et al. 2022

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Quantum information networks can transmit quantum states and perform quantum operations between different quantum network nodes, which are essential for various applications of quantum information technology in the future. In this paper, a potentially practical scheme for implementing nonlocal quantum controlled-not (CNOT) gate operations on quantum-dot-confined electron spins between two quantum network nodes is presented. The scheme can realize parallel teleportation of two nonlocal quantum CNOT gates simultaneously by employing hyperentangled photon pairs to establish quantum channel, which can effectively improve the channel capacity and operational speed. The core of the scheme are two kinds of photon-spin hybrid quantum CNOT gate working in a failure-heralded and fidelity-robust fashion. With the heralded mechanism, the nonlocal CNOT gates can be implementated with unity fidelities in principle, even if the particularly ideal conditions commonly used in other schemes are not satisfied strictly. Our analysis and calculations indicate that the scheme can be demonstrated efficiently (with efficiency exceeding 99%) with current or near-future technologies. Moreover, the utilized photon-spin hybrid quantum gates can be regarded as universal modules for many other quantum information processing (QIP) tasks. Therefore, the scheme is potential for constructing elementary quantum networks, and realizing nolocal QIP with high channel capacities, high fidelities, and high efficiencies.

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Experimental one-step deterministic polarization entanglement purification

Cited by 39 publications

References 47 publications

Optical demonstration of quantum fault-tolerant threshold

Optical demonstration of quantum fault-tolerant threshold

Variational quantum circuit learning of entanglement purification in multi-degree-of-freedom

Scheme for implementing nonlocal high-fidelity quantum controlled-not gates on quantum-dot-confined electron spins using optical microcavities and photonic hyperentanglement

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