High-Fidelity, High-Scalability Two-Qubit Gate Scheme for Superconducting Qubits

Xu, Yuan; Chu, Ji; Yuan, Jiahao; Qiu, Jiawei; Zhou, Yuxuan; Zhang, Libo; Tan, Xinsheng; Yu, Yang; Liu, Song; Li, Jian; Yan, Fei; Yu, Dapeng

doi:10.1103/physrevlett.125.240503

Cited by 160 publications

(107 citation statements)

References 35 publications

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“…Over the full range of indium bump height expected from the bonding process, the predicted maximum achievable fidelity (taken as the minimum of the coherence-limited and unitary fidelity) varies from just under 99.0-99.5%. For an initial proof of concept, this range is acceptable; however, to push toward fidelities exceeding 99% or to employ this as part of a tunable coupler scheme 41,42 , efforts will be needed to reduce the spread. Additional calibration of the force applied during the bonding process and design revisions to reduce the sensitivity of the coupling to bump height by changing the paddle geometry could reduce this variation further for gate schemes requiring a tighter tolerance.…”

Section: Device Fabrication Assembly and Validationmentioning

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: Device Fabrication Assembly and Validationmentioning

confidence: 99%

Entanglement across separate silicon dies in a modular superconducting qubit device

et al. 2021

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“…However, this tunability is usually achieved at the cost of introducing additional decoherence or circuit complexity. [ 70–76 ] Alternatively, parametric modulation of qubits' frequencies can be used to realize this tunability [ 77–79 ] without coupling devices, and thus simplifies the circuit.…”

Section: Parametric Couplingsmentioning

confidence: 99%

“…[ 73 ] Alternatively, the cross‐Kerr ZZ‐interaction can be obtained for two qubits with large qubit‐frequency difference, and, in this case, controlled‐phase gates can be implemented. [ 74,75 ] As the total interaction is adjusted from large detuned qubit‐coupler interaction, the unwanted qubit interactions can also be completely turned off, and thus high‐fidelity quantum operations can be possible.…”

Section: Parametric Couplingsmentioning

confidence: 99%

Topological Photonics on Superconducting Quantum Circuits with Parametric Couplings

Xue

2021

Adv Quantum Tech

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Topological phases of matter are an exotic phenomenon in modern condensed matter physics, which has attracted much attention due to the unique boundary states and transport properties. Recently, this topological concept in electronic materials has been exploited in many other fields of physics. Motivated by designing and controlling the behavior of electromagnetic waves in optical, microwave, and sound frequencies, topological photonics emerges as a rapid growing research field. Due to the flexibility and diversity of superconducting quantum circuits system, it is a promising platform to realize exotic topological phases of matter and to probe and explore topologically‐protected effects in new ways. Here, theoretical and experimental advances of topological photonics on superconducting quantum circuits—via the experimentally demonstrated parametric tunable coupling techniques, including using of the superconducting transmission line resonator, superconducting qubits, and their coupled system—are reviewed. On superconducting circuits, the flexible interactions and intrinsic nonlinearity make topological photonics in this system not only a simple photonic analog of topological effects for novel devices, but also a realm of exotic but less‐explored fundamental physics.

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“…We focus on two-qubit circuits over the Clifford+CS gate set, which consists of the Clifford gates together with the non-Clifford controlled-phase gate CS = diag(1, 1, 1, i). The CS gate has received recent attention as an alternative to the T-gate in methods for fault-tolerant quantum computing 30,31 and due to its natural implementation as an entangling operation in certain superconducting qubit systems [32][33][34][35] whose fidelity is approaching that of single-qubit gates 36,37 . Our algorithm produces an optimal circuit in a number of arithmetic operations linear in the length of the optimal decomposition.…”

Section: Introductionmentioning

confidence: 99%

Optimal two-qubit circuits for universal fault-tolerant quantum computation

Glaudell

Ross

2021

npj Quantum Inf

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We study two-qubit circuits over the Clifford+CS gate set, which consists of the Clifford gates together with the controlled-phase gate CS = diag(1, 1, 1, i). The Clifford+CS gate set is universal for quantum computation and its elements can be implemented fault-tolerantly in most error-correcting schemes through magic state distillation. Since non-Clifford gates are typically more expensive to perform in a fault-tolerant manner, it is often desirable to construct circuits that use few CS gates. In the present paper, we introduce an efficient and optimal synthesis algorithm for two-qubit Clifford+CS operators. Our algorithm inputs a Clifford+CS operator U and outputs a Clifford+CS circuit for U, which uses the least possible number of CS gates. Because the algorithm is deterministic, the circuit it associates to a Clifford+CS operator can be viewed as a normal form for that operator. We give an explicit description of these normal forms and use this description to derive a worst-case lower bound of $$5{{\rm{log}}}_{2}(\frac{1}{\epsilon })+O(1)$$ 5 log 2 ( 1 ϵ ) + O ( 1 ) on the number of CS gates required to ϵ-approximate elements of SU(4). Our work leverages a wide variety of mathematical tools that may find further applications in the study of fault-tolerant quantum circuits.

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High-Fidelity, High-Scalability Two-Qubit Gate Scheme for Superconducting Qubits

Cited by 160 publications

References 35 publications

Entanglement across separate silicon dies in a modular superconducting qubit device

Entanglement across separate silicon dies in a modular superconducting qubit device

Topological Photonics on Superconducting Quantum Circuits with Parametric Couplings

Optimal two-qubit circuits for universal fault-tolerant quantum computation

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