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arXiv · 2307.03232

Experimental demonstration of a high-fidelity virtual two-qubit gate

Akhil Pratap Singh·Kosuke Mitarai·Yasunari Suzuki·Kentaro Heya·Yutaka Tabuchi·Keisuke Fujii·Yasunobu Nakamura
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Abstract

We experimentally demonstrate a virtual two-qubit gate and characterize it using quantum process tomography~(QPT). The virtual two-qubit gate decomposes an actual two-qubit gate into single-qubit unitary gates and projection gates in quantum circuits for expectation-value estimation. We implement projection gates via mid-circuit measurements. The deterministic sampling scheme reduces the number of experimental circuit evaluations required for decomposing a virtual two-qubit gate. We also apply quantum error mitigation to suppress the effect of measurement errors and improve the average gate fidelity of a virtual controlled-$Z$ (CZ) gate to $f_{\rm av} = 0.9938 \pm 0.0002$. Our results highlight a practical approach to implement virtual two-qubit gates with high fidelities, which are useful for simulating quantum circuits using fewer qubits and implementing two-qubit gates on a distant pair of qubits.

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Akhil Pratap Singh, Kosuke Mitarai, Yasunari Suzuki, Kentaro Heya, Yutaka Tabuchi, Keisuke Fujii, Yasunobu Nakamura. 2023-07-06. Experimental demonstration of a high-fidelity virtual two-qubit gate. https://doi.org/10.1103/physrevresearch.6.013235

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