Deterministic multi-qubit entanglement in a quantum network

Zhong, Youpeng; Chang, Hung-Shen; Bienfait, Audrey; Dumur, Étienne; Chou, Ming-Han; Conner, Christopher R.; Grebel, Joel; Povey, Rhys; Yan, Haoxiong; Schuster, David I.; Cleland, A. N.

doi:10.1038/s41586-021-03288-7

Cited by 117 publications

(79 citation statements)

References 51 publications

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“…Heralded entanglement protocols, whereby entanglement is generated probabilistically, have now reached entanglement rates up to 200 Hz [6][7][8][9][10][11][12] . Superconducting systems have established direct exchange of quantum information over cryogenic microwave channels [13][14][15][16][17][18] , which is particularly useful toward interconnects of intermediate range such as between dilution refrigerators. Yet, in the context of superconducting qubit based processors, none of these methods are likely to outperform local gates between qubits, which can achieve coupling rates in the tens of MHz and fidelities reaching 99.9% [19][20][21][22][23] .…”

Section: Introductionmentioning

confidence: 99%

Entanglement across separate silicon dies in a modular superconducting qubit device

et al. 2021

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Assembling future large-scale quantum computers out of smaller, specialized modules promises to simplify a number of formidable science and engineering challenges. One of the primary challenges in developing a modular architecture is in engineering high fidelity, low-latency quantum interconnects between modules. Here we demonstrate a modular solid state architecture with deterministic inter-module coupling between four physically separate, interchangeable superconducting qubit integrated circuits, achieving two-qubit gate fidelities as high as 99.1 ± 0.5% and 98.3 ± 0.3% for iSWAP and CZ entangling gates, respectively. The quality of the inter-module entanglement is further confirmed by a demonstration of Bell-inequality violation for disjoint pairs of entangled qubits across the four separate silicon dies. Having proven out the fundamental building blocks, this work provides the technological foundations for a modular quantum processor: technology which will accelerate near-term experimental efforts and open up new paths to the fault-tolerant era for solid state qubit architectures.

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Section: Introductionmentioning

confidence: 99%

Entanglement across separate silicon dies in a modular superconducting qubit device

et al. 2021

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“…In the case of continuous-variable propagating fields, F ct = 0 for arbitrary input states, while for the particular task of teleporting coherent states, one finds F ct = 1/2 ( 9 ). For qubit states, this threshold is different, namely, F ct, qubit = 2/3, and has been experimentally overcome with superconducting qubits ( 11 , 12 ). These threshold values are connected with a violation of the Clauser-Horne-Shimony-Holt inequality that expresses the fact that nature cannot be described by local hidden-variable theories ( 8 , 13 ).…”

Section: Introductionmentioning

confidence: 99%

Experimental quantum teleportation of propagating microwaves

et al. 2021

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“…Quantum communication is of significant interest for the generation of remote entanglement and the secure transmission of information, as well as for distributed quantum computing [1][2][3][4][5][6][7] . There are several demonstrations of long-distance quantum communication protocols using optical methods, in parallel with demonstrations of similar protocols using microwave-frequency photons, including Bell state entanglement of remote qubits as well as the transmission of multi-qubit entangled states [8][9][10][11][12][13][14][15][16] . Microwave-frequency phonons, as opposed to photons, can also be used for quantum communication as well as for coupling hybrid quantum systems [17][18][19][20] , in the latter case taking advantage of the strong strain coupling in some optical as well as atomicscale systems.…”

Section: Introductionmentioning

confidence: 99%

Quantum communication with itinerant surface acoustic wave phonons

et al. 2021

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Surface acoustic waves are commonly used in classical electronics applications, and their use in quantum systems is beginning to be explored, as evidenced by recent experiments using acoustic Fabry–Pérot resonators. Here we explore their use for quantum communication, where we demonstrate a single-phonon surface acoustic wave transmission line, which links two physically separated qubit nodes. Each node comprises a microwave phonon transducer, an externally controlled superconducting variable coupler, and a superconducting qubit. Using this system, precisely shaped individual itinerant phonons are used to coherently transfer quantum information between the two physically distinct quantum nodes, enabling the high-fidelity node-to-node transfer of quantum states as well as the generation of a two-node Bell state. We further explore the dispersive interactions between an itinerant phonon emitted from one node and interacting with the superconducting qubit in the remote node. The observed interactions between the phonon and the remote qubit promise future quantum-optics-style experiments with itinerant phonons.

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Deterministic multi-qubit entanglement in a quantum network

Cited by 117 publications

References 51 publications

Entanglement across separate silicon dies in a modular superconducting qubit device

Entanglement across separate silicon dies in a modular superconducting qubit device

Experimental quantum teleportation of propagating microwaves

Quantum communication with itinerant surface acoustic wave phonons

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