Quantum Instruction Set Design for Performance

Huang, Cupjin; Wang, Tenghui; Wu, Feng; Ding, Derui; Ye, Qi; Kong, Linghang; Zhang, Fang; Ni, Xiaotong; Song, Zhanqian; Shi, Yuanming; Zhao, Hui‐Hai; Deng, Chuiwen; Chen, Jianxin

doi:10.48550/arxiv.2105.06074

Cited by 6 publications

(14 citation statements)

References 36 publications

(53 reference statements)

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“…These evaluation results are similar to the results by using the analytical decomposition method in [17], demonstrating the good performance of the numerical decomposition method. Moreover, Figure 3 We note that arbitrary single-qubit gates are typically required to find an exact decomposition 2 for an arbitrary target unitary.…”

Section: Gate Recompilationsupporting

confidence: 79%

Software mitigation of coherent two-qubit gate errors

Lao¹,

Korotkov²,

Zhang³

et al. 2021

Preprint

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Two-qubit gates are important components of quantum computing. However, unwanted interactions between qubits (so-called parasitic gates) can be particularly problematic and degrade the performance of quantum applications. In this work, we present two software methods to mitigate parasitic two-qubit gate errors. The first approach is built upon the KAK decomposition and keeps the original unitary decomposition for the error-free native two-qubit gate. It counteracts a parasitic two-qubit gate by only applying single-qubit rotations and therefore has no two-qubit gate overhead. We show the optimal choice of single-qubit mitigation gates. The second approach applies a numerical optimisation algorithm to re-compile a target unitary into the error-parasitic two-qubit gate plus single-qubit gates. We demonstrate these approaches on the CPhase-parasitic iSWAP-like gates. The KAK-based approach helps decrease unitary infidelity by a factor of 3 compared to the noisy implementation without error mitigation. When arbitrary single-qubit rotations are allowed, recompilation could completely mitigate the effect of parasitic errors but may require more native gates than the KAK-based approach. We also compare their average gate fidelity under realistic noise models, including relaxation and depolarising errors. Numerical results suggest that different approaches are advantageous in different error regimes, providing error mitigation guidance for near-term quantum computers.

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Section: Gate Recompilationsupporting

confidence: 79%

Software mitigation of coherent two-qubit gate errors

Lao¹,

Korotkov²,

Zhang³

et al. 2021

Preprint

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show abstract

“…In our proposal, we focus on an √ iswap-like gate, which mixes |01 and |10 states while also generally results in phase accumulation in |00 and |11 states. This class of gates consists of perfect entanglers, and √ iswap has been shown to provide powerful compilation capabilities rivaling those of iswap and cnot gates [16].…”

Section: Introductionmentioning

confidence: 99%

Fast Flux Entangling Gate for Fluxonium Circuits

Chen,

Nesterov,

Manucharyan

et al. 2021

Preprint

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We analyze a high-fidelity two-qubit gate using fast flux pulses on superconducting fluxonium qubits. The gate is realized by temporarily detuning magnetic flux through fluxonium loop away from the half flux quantum sweet spot. We simulate dynamics of two capacitively coupled fluxoniums during the flux pulses and optimize the pulse parameters to obtain a highly accurate √ iswap-like entangling gate. We also evaluate the effect of the flux noise and qubit relaxation on the gate fidelity. Our results demonstrate that the gate error remains below 10 −4 for currently achievable magnitude of the flux noise and qubit relaxation time.

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“…A two-qubit entangling gate along with a single qubit gate can be used to realize arbitrary unitary operations needed for quantum computation. A high fidelity and high efficiency two-qubit entangling gate is a key element in quantum computation, which will reduce overhead for performing quantum error corrections for large scale quantum computation [3]. The most efficient twoqubit gates belong to the CNOT gate and iSWAP gate families [3].…”

mentioning

confidence: 99%

“…A high fidelity and high efficiency two-qubit entangling gate is a key element in quantum computation, which will reduce overhead for performing quantum error corrections for large scale quantum computation [3]. The most efficient twoqubit gates belong to the CNOT gate and iSWAP gate families [3]. With the help of arbitrary single-qubit gates, it will only need up to 3 uses of CNOT or iSWAP gate to realize arbitrary two-qubit unitary evolution [3].…”

mentioning

confidence: 99%

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A two-qubit entangling gate based on a two-spin gadget

Yang¹

2022

Preprint

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The faster speed and operational convenience of two-qubit gate with flux bias control makes it an important candidate for future large-scale quantum computers based on high coherence flux qubits. Based on a properly designed two-spin gadget which has small gaps during the evolution of energy levels, we build a CNOT-equivalent gate which can reach a fidelity larger than 99.9% within 40ns. Moreover, we also use the Schrieffer-Wolff Transformation to translate the spin model Ising coefficients schedule to circuit model flux bias schedule for realistic flux qubit circuits coupled by a tunable rf-squid. The two-qubit entangling gate scheme introduced here is suitable for realizing efficient two-qubit gates in the large scale flux qubit systems dominated by inductive couplings. Comparing with the current gate-based quantum computation systems dominated by capacitive couplings, it can resolve the conflict between the speed and a high coherence.

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Quantum Instruction Set Design for Performance

Cited by 6 publications

References 36 publications

Software mitigation of coherent two-qubit gate errors

Software mitigation of coherent two-qubit gate errors

Fast Flux Entangling Gate for Fluxonium Circuits

A two-qubit entangling gate based on a two-spin gadget

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