Genuine 12-Qubit Entanglement on a Superconducting Quantum Processor

Gong, Ming; Chen, Ming-Cheng; Zheng, Yingkui; Wang, Shiyu; Zha, Chen; Deng, Hui; Yan, Zhiguang; Rong, Hao; Wu, Yulin; Li, Shaowei; Chen, Fusheng; Zhao, Youwei; Liang, Futian; Lin, Jin; Xu, Yu; Guo, Cheng; Sun, Lihua; Castellano, Anthony D.; Wang, Haohua; Peng, Cheng-Zhi; Lu, Chao‐Yang; Zhu, Xiaobo; Pan, Jian-Wei

doi:10.1103/physrevlett.122.110501

Cited by 193 publications

(164 citation statements)

References 38 publications

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“…Cluster states have been experimentally demonstrated using trapped ions [16,17], squeezed states of light [18][19][20], superconducting qubits [21], and photons [22][23][24][25]. The most common approach to constructing multiphotonic entanglement begins with Bell pairs of photons, generated by parametric down conversion, and builds up entanglement pairwise through two-photon interference and measurement ('fusion' gates) [26].…”

Section: Introductionmentioning

confidence: 99%

Generation of arbitrary all-photonic graph states from quantum emitters

2019

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We present protocols to generate arbitrary photonic graph states from quantum emitters that are in principle deterministic. We focus primarily on two-dimensional cluster states of arbitrary size due to their importance for measurement-based quantum computing. Our protocols for these and many other types of two-dimensional graph states require a linear array of emitters in which each emitter can be controllably pumped, rotated about certain axes, and entangled with its nearest neighbors. We show that an error on one emitter produces a localized region of errors in the resulting graph state, where the size of the region is determined by the coordination number of the graph. We describe how these protocols can be implemented for different types of emitters, including trapped ions, quantum dots, and nitrogen-vacancy centers in diamond. is a 2×m cluster state, where m is the number of cycles. Schemes to create ladder-type cluster states using trapped ions have also been proposed [29]. However, for universal quantum computation, a larger twodimensional grid (n by m, with n, m?2) is needed; moreover, fault-tolerant universal computation requires a three-dimensional grid [30]. One interesting proposal to create a larger two-dimensional grid using feedback and atom-photon interactions in a cavity has been put forward [31]. However, this approach requires coupling the emitter to a chiral waveguide, which has yet to be demonstrated experimentally with high efficiency.In this paper, we propose an in-principle deterministic method to produce an arbitrary graph state that does not require photon-photon interactions. Instead, the entanglement is created between emitters and then transferred onto photons through optical pumping. This is similar to the idea presented in [28], although here, in addition to being able to create states corresponding to arbitrary graphs of any size, our scheme also allows for the entangling operations between emitters to occur after the photon pumping. Combined with heralding of the emission process, this allows one to perform the typically costly entangling operation only if there is a successful photon emission. Moreover, we show that, in a precise sense, our approach allows for the maximum possible delay in transferring the entanglement from the emitters onto the photons. Our protocol allows for arbitrary sized n by m clusters, given a linear array of n emitters, where each emitter can be entangled with its nearest neighbors. The operations required of the linear array are only a single two-emitter entangling gate and a photon pumping operation. For three-dimensional clusters, which permit fault-tolerant universal computation, our protocol requires a two-dimensional grid of nearest-neighbor connected emitters.This paper is organized as follows. First, a brief overview of the graph state formalism is provided. Second, our new framework to produce arbitrary graph states using emitters, assuming entangling gates are available between emitters, is presented. Then, we discuss concrete realizations ...

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Section: Introductionmentioning

confidence: 99%

Generation of arbitrary all-photonic graph states from quantum emitters

2019

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“…We benchmark this gate by preparing Bell states of two atoms with a fidelity F ≥ 95.0(2)%, averaged across five pairs of atoms. After accounting for state preparation and measurement errors, we extract the entanglement operation fidelity to be F c ≥ 97.4(3)%, competitive with other leading platforms capable of simulta-neous manipulation of ten or more qubits [18][19][20][21]. We additionally demonstrate a proof-of-principle implementation of the three-qubit Toffoli gate, wherein two atoms simultaneously constrain a third atom through the Rydberg blockade, highlighting the potential use of Rydberg interactions for efficient multi-qubit operations [14,22].…”

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confidence: 99%

Parallel Implementation of High-Fidelity Multiqubit Gates with Neutral Atoms

et al. 2019

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We report the implementation of universal two-and three-qubit entangling gates on neutral atom qubits encoded in long-lived hyperfine ground states. The gates are mediated by excitation to strongly interacting Rydberg states, and are implemented in parallel on several clusters of atoms in a one-dimensional array of optical tweezers. Specifically, we realize the controlled-phase gate, enacted by a novel, fast protocol involving only global coupling of two qubits to Rydberg states. We benchmark this operation by preparing Bell states with fidelity F ≥ 95.0(2)%, and extract gate fidelity ≥ 97.4(3)%, averaged across five atom pairs. In addition, we report a proof-of-principle implementation of the three-qubit Toffoli gate, in which two control atoms simultaneously constrain the behavior of one target atom. These experiments demonstrate key ingredients for high-fidelity quantum information processing in a scalable neutral atom platform.

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“…In the following we hence give an overview of a selection of contemporary theoretical techniques, and highlight their application in exemplary platforms. First, we consider few body systems such as photons and ion traps (see Boxes 2 and 3, respectively), before we move on to another (this time many-body) target platform for current quantum technologies: atomic gases (see Box 4), noting that other promising realisations of multipartite entanglement exist (e.g., using superconducting qubits [194][195][196]) but their detailed description goes beyond the scope of this review.…”

Section: Contemporary Challenges: Multipartite Entanglementmentioning

confidence: 99%

Entanglement certification from theory to experiment

et al. 2018

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Entanglement is an important resource that allows quantum technologies to go beyond the classically possible. There are many ways quantum systems can be entangled, ranging from the archetypal two-qubit case to more exotic scenarios of entanglement in high dimensions or between many parties. Consequently, a plethora of entanglement quantifiers and classifiers exist, corresponding to different operational paradigms and mathematical techniques.However, for most quantum systems, exactly quantifying the amount of entanglement is extremely demanding, if at all possible. This is further exacerbated by the difficulty of experimentally controlling and measuring complex quantum states. Consequently, there are various approaches for experimentally detecting and certifying entanglement when exact quantification is not an option, with a particular focus on practically implementable methods and resource efficiency. The applicability and performance of these methods strongly depends on the assumptions one is willing to make regarding the involved quantum states and measurements, in short, on the available prior information about the quantum system. In this review we discuss the most commonly used paradigmatic quantifiers of entanglement. For these, we survey state-of-the-art detection and certification methods, including their respective underlying assumptions, from both a theoretical and experimental point of view.In the early twentieth century, the phenomenon of quantum entanglement rose to prominence as a central feature of the famous thought experiment by Einstein, Podolsky, and Rosen [1]. Initially disregarded as a mathematical artefact that showcases the incompleteness of quantum theory, the properties of entanglement were largely ignored until 1964, when John Bell famously proposed an experimentally testable inequality able to distinguish between the predictions of quantum mechanics and those of any local-realistic theory [2]. With the advent of the first experimental tests [3], spearheaded by , emerged the realisation that entanglement constitutes a resource for information processing *

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Genuine 12-Qubit Entanglement on a Superconducting Quantum Processor

Cited by 193 publications

References 38 publications

Generation of arbitrary all-photonic graph states from quantum emitters

Generation of arbitrary all-photonic graph states from quantum emitters

Parallel Implementation of High-Fidelity Multiqubit Gates with Neutral Atoms

Entanglement certification from theory to experiment

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