Divide-and-conquer verification method for noisy intermediate-scale quantum computation

Several noisy intermediate-scale quantum computations can be regarded as logarithmic-depth quantum circuits on a sparse quantum computing chip, where two-qubit gates can be directly applied on only some pairs of qubits. In this paper, we propose a method to efficiently verify such noisy intermediate...

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Main Authors: Yuki Takeuchi, Yasuhiro Takahashi, Tomoyuki Morimae, Seiichiro Tani
Format: Article
Language:English
Published: Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften 2022-07-01
Series:Quantum
Online Access:https://quantum-journal.org/papers/q-2022-07-07-758/pdf/
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author Yuki Takeuchi
Yasuhiro Takahashi
Tomoyuki Morimae
Seiichiro Tani
author_facet Yuki Takeuchi
Yasuhiro Takahashi
Tomoyuki Morimae
Seiichiro Tani
author_sort Yuki Takeuchi
collection DOAJ
description Several noisy intermediate-scale quantum computations can be regarded as logarithmic-depth quantum circuits on a sparse quantum computing chip, where two-qubit gates can be directly applied on only some pairs of qubits. In this paper, we propose a method to efficiently verify such noisy intermediate-scale quantum computation. To this end, we first characterize small-scale quantum operations with respect to the diamond norm. Then by using these characterized quantum operations, we estimate the fidelity $\langle\psi_t|\hat{\rho}_{\rm out}|\psi_t\rangle$ between an actual $n$-qubit output state $\hat{\rho}_{\rm out}$ obtained from the noisy intermediate-scale quantum computation and the ideal output state (i.e., the target state) $|\psi_t\rangle$. Although the direct fidelity estimation method requires $O(2^n)$ copies of $\hat{\rho}_{\rm out}$ on average, our method requires only $O(D^32^{12D})$ copies even in the worst case, where $D$ is the denseness of $|\psi_t\rangle$. For logarithmic-depth quantum circuits on a sparse chip, $D$ is at most $O(\log{n})$, and thus $O(D^32^{12D})$ is a polynomial in $n$. By using the IBM Manila 5-qubit chip, we also perform a proof-of-principle experiment to observe the practical performance of our method.
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spelling doaj.art-11bcb072abb94e44bef36c61a6cff6252022-12-22T01:21:51ZengVerein zur Förderung des Open Access Publizierens in den QuantenwissenschaftenQuantum2521-327X2022-07-01675810.22331/q-2022-07-07-75810.22331/q-2022-07-07-758Divide-and-conquer verification method for noisy intermediate-scale quantum computationYuki TakeuchiYasuhiro TakahashiTomoyuki MorimaeSeiichiro TaniSeveral noisy intermediate-scale quantum computations can be regarded as logarithmic-depth quantum circuits on a sparse quantum computing chip, where two-qubit gates can be directly applied on only some pairs of qubits. In this paper, we propose a method to efficiently verify such noisy intermediate-scale quantum computation. To this end, we first characterize small-scale quantum operations with respect to the diamond norm. Then by using these characterized quantum operations, we estimate the fidelity $\langle\psi_t|\hat{\rho}_{\rm out}|\psi_t\rangle$ between an actual $n$-qubit output state $\hat{\rho}_{\rm out}$ obtained from the noisy intermediate-scale quantum computation and the ideal output state (i.e., the target state) $|\psi_t\rangle$. Although the direct fidelity estimation method requires $O(2^n)$ copies of $\hat{\rho}_{\rm out}$ on average, our method requires only $O(D^32^{12D})$ copies even in the worst case, where $D$ is the denseness of $|\psi_t\rangle$. For logarithmic-depth quantum circuits on a sparse chip, $D$ is at most $O(\log{n})$, and thus $O(D^32^{12D})$ is a polynomial in $n$. By using the IBM Manila 5-qubit chip, we also perform a proof-of-principle experiment to observe the practical performance of our method.https://quantum-journal.org/papers/q-2022-07-07-758/pdf/
spellingShingle Yuki Takeuchi
Yasuhiro Takahashi
Tomoyuki Morimae
Seiichiro Tani
Divide-and-conquer verification method for noisy intermediate-scale quantum computation
Quantum
title Divide-and-conquer verification method for noisy intermediate-scale quantum computation
title_full Divide-and-conquer verification method for noisy intermediate-scale quantum computation
title_fullStr Divide-and-conquer verification method for noisy intermediate-scale quantum computation
title_full_unstemmed Divide-and-conquer verification method for noisy intermediate-scale quantum computation
title_short Divide-and-conquer verification method for noisy intermediate-scale quantum computation
title_sort divide and conquer verification method for noisy intermediate scale quantum computation
url https://quantum-journal.org/papers/q-2022-07-07-758/pdf/
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AT yasuhirotakahashi divideandconquerverificationmethodfornoisyintermediatescalequantumcomputation
AT tomoyukimorimae divideandconquerverificationmethodfornoisyintermediatescalequantumcomputation
AT seiichirotani divideandconquerverificationmethodfornoisyintermediatescalequantumcomputation