論文

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2019年8月9日

Methodology for replacing indirect measurements with direct measurements

Physical Review Research
  • Kosuke Mitarai
  • ,
  • Keisuke Fujii

担当区分
筆頭著者
1
開始ページ
013006
終了ページ
DOI
10.1103/PhysRevResearch.1.013006

In quantum computing, the indirect measurement of unitary operators such as
the Hadamard test plays a significant role in many algorithms. However, in
certain cases, the indirect measurement can be reduced to the direct
measurement, where a quantum state is destructively measured. Here we
investigate in what cases such a replacement is possible and develop a general
methodology for trading an indirect measurement with sequential direct
measurements. The results can be applied to construct quantum circuits to
evaluate the analytical gradient, metric tensor, Hessian, and even higher order
derivatives of a parametrized quantum state. Also, we propose a new method to
measure the out-of-time-order correlator based on the presented protocol. Our
protocols can reduce the depth of the quantum circuit significantly by making
the controlled operation unnecessary and hence are suitable for
quantum-classical hybrid algorithms on near-term quantum computers.

リンク情報
DOI
https://doi.org/10.1103/PhysRevResearch.1.013006
arXiv
http://arxiv.org/abs/arXiv:1901.00015
共同研究・競争的資金等の研究課題
古典 - 量子ハイブリッドアルゴリズムの実験実証とその核スピン超偏極への応用
Arxiv Url
http://arxiv.org/abs/1901.00015v2
Arxiv Url
http://arxiv.org/pdf/1901.00015v2 本文へのリンクあり