Quantum walks on a programmable two-dimensional 62-qubit superconducting processor

Gong, Ming; Wang, Shiyu; Zha, Chen; Chen, Ming-Cheng; Huang, He-Liang; Wu, Yulin; Zhu, Qing–Ling; Zhao, Youwei; Li, Shaowei; Guo, Shaojun; Qian, Haoran; Ye, Yangsen; Chen, Fusheng; Ying, Chong; Yu, Jiabing; Fan, Daojin; Wu, Donghui; Su, Hong; Deng, Hui; Rong, Hao; Zhang, Kaili; Cao, Shuchao; Lin, Jin; Xu, Yu; Sun, Lihua; Guo, Cheng; Li, Na; Liang, Futian; Bastidas, V. M.; Nemoto, Kae; Munro, William J.; Huo, Yongheng; Lu, Chao‐Yang; Peng, Cheng-Zhi; Zhu, Xiaobo; Pan, Jian-Wei

doi:10.1126/science.abg7812

Cited by 264 publications

(127 citation statements)

References 29 publications

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“…In comparison with traditional ensemble approach, it has the benefit of deterministic entanglement preparation. Be-sides, the long-range dipole interaction also provides a promising interface [19][20][21] for quantum computers with single atoms in arrayed optical tweezers [22], and the interaction with microwave photons also enables a promising interface [23] for super-conducting quantum computers [24,25]. Significant experimental progresses have been achieved so far, such as the observation collective Rabi oscillation [26], on demand single-photon source [27] and atom-photon entanglement [28].…”

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confidence: 99%

Single-shot measurement of a Rydberg superatom via collective photon burst

Yang,

Li,

Zhou

et al. 2021

Preprint

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With Rydberg dipole interactions, a mesoscopic atomic ensemble may behave like a two-level single atom, resulting in the so-called picture of superatom. It is in potential a strong candidate as a qubit in quantum information science, especially for efficient coupling with single photons via collective enhancement that is essential for building quantum internet to connect remote quantum computers. Previously, preliminary studies have been carried out in demonstrating basic concept of Rydberg superatom, a single-photon source, and entanglement with a single photon, etc. While a crucial element of single-shot qubit measurement is still missing. Here we realize the deterministic measurement of a superatom qubit via photon burst in a single shot. We make use of a low-finesse ring cavity to enhance the atom-photon interaction and obtain an in-fiber retrieval efficiency of 44%. Harnessing dipole interaction between two Rydberg levels, we may either create a sequence of multiple single photons or nothing, conditioned on the initial qubit state. We achieve a singleshot measurement fidelity of 93.2% in 4.8 µs. Our work complements the experimental toolbox of harnessing Rydberg superatom for quantum information applications.

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confidence: 99%

Single-shot measurement of a Rydberg superatom via collective photon burst

Yang,

Li,

Zhou

et al. 2021

Preprint

Self Cite

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“…In appendix B we show that, in the limit δτ → 0 + , the dynamical map of equation ( 22) approximates the solution of the target master equation (11) with dephasing rates Γ j = c 2 j δτ . The dephasing rates are therefore determined by the strength of the interaction and the collision time, conveying the intuition that the system undergoes decoherence when it interacts strongly for a short time as well as when the interaction is weaker, but it lasts longer.…”

Section: Collision Algorithmmentioning

confidence: 95%

“…The relation also applies in the opposite direction, and QW algorithms can be implemented by the dynamics of isolated and controllable physical systems which act as analog simulators. Quantum walkers have been experimentally realized with trapped ions [8], phonons of trapped ions [9], neutral atoms in optical traps [10] and excitation in superconducting circuits [11]. In the digital setting of gate-based quantum computers, the implementation of QW is still challenging as it requires circuits of a significant depth.…”

Section: Introductionmentioning

confidence: 99%

Strategies to simulate dephasing-assisted quantum transport on digital quantum computers

2022

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Simulating charge and energy transfer in extended molecular networks requires an effective model to include the environment because it significantly affects the quantum dynamics. A prototypical effect known as Environment-Assisted Quantum Transport (ENAQT) consists in the enhancement of the transfer efficiency by the interaction with an environment. A simple description of this phenomenon is obtained by a quantum master equation describing a quantum walk over the molecular network in the presence of inter-site decoherence. We consider the problem of simulating the dynamics underlying ENAQT in a digital quantum computer. Two different quantum algorithms are introduced, the first one based on stochastic Hamiltonians and the second one based on a collision scheme. We test both algorithms by simulating ENAQT in a small molecular network on a quantum computer emulator and provide a comparative analysis of the two approaches. Both algorithms can be implemented in a memory efficient encoding with the number of required qubits scaling logarithmically with the size of the simulated system while the number of gates increases quadratically. We discuss the algorithmic quantum trajectories generated by the two simulation strategies showing that they realize distinct unravellings of the site-dephasing master equation. In our approach, the non-unitary dynamics of the open system is obtained through effective representations of the environment, paving the way to digital quantum simulations of quantum transport influenced by structured environments.

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“…It is widely believed that the era of practical quantum computing is now dawning. With an increasing tempo, new records for qubit count are set and then surpassed [1][2][3][4][5][6][7]. However, as any given platform scales it is likely that there will be critical device sizes that will prove difficult to scale beyond.…”

Section: Introduction and Overviewmentioning

confidence: 99%

Multicore Quantum Computing

Jnane,

Undseth,

Cai

et al. 2022

Preprint

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Any architecture for practical quantum computing must be scalable. An attractive approach is to create multiple cores, computing regions of fixed size that are well-spaced but interlinked with communication channels. This exploded architecture can relax the demands associated with a single monolithic device: the complexity of control, cooling and power infrastructure as well as the difficulties of cross-talk suppression and near-perfect component yield. Here we explore interlinked multicore architectures through analytic and numerical modelling. While elements of our analysis are relevant to diverse platforms, our focus is on semiconductor electron spin systems in which numerous cores may exist on a single chip. We model shuttling and microwave-based interlinks and estimate the achievable fidelities, finding values that are encouraging but markedly inferior to intra-core operations. We therefore introduce optimsed entanglement purification to enable highfidelity communication, finding that 99.5% is a very realistic goal. We then assess the prospects for quantum advantage using such devices in the NISQ-era and beyond: we simulate recently proposed exponentially-powerful error mitigation schemes in the multicore environment and conclude that these techniques impressively suppress imperfections in both the inter-and intra-core operations.

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Quantum walks on a programmable two-dimensional 62-qubit superconducting processor

Cited by 264 publications

References 29 publications

Single-shot measurement of a Rydberg superatom via collective photon burst

Single-shot measurement of a Rydberg superatom via collective photon burst

Strategies to simulate dephasing-assisted quantum transport on digital quantum computers

Multicore Quantum Computing

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