@techreport{oai:ipsj.ixsq.nii.ac.jp:00213200,
 author = {Nobuyuki, Yoshioka and Hideaki, Hakoshima and Yuichiro, Matsuzaki and Yuuki, Tokunaga and Yasunari, Suzuki and Suguru, Endo and Nobuyuki, Yoshioka and Hideaki, Hakoshima and Yuichiro, Matsuzaki and Yuuki, Tokunaga and Yasunari, Suzuki and Suguru, Endo},
 issue = {6},
 month = {Oct},
 note = {The control over the effect of noise is crucial for extracting reliable results from noisy quantum computers. Since current available quantum resources are not fully fault-tolerant, it is essential to develop practical quantum error mitigation (QEM) methods to compensate for unwanted computation errors. Here, we propose a novel error mitigation scheme: the generalized quantum subspace expansion method that can mitigate dominant errors in quantum computers. Exploitation of the substantially extended subspace allows us to efficiently mitigate the noise present in the spectra of a given Hamiltonian in a noise-agnostic way. We found two practical subspaces for practical error mitigation: the subspaces spanned by powers of the noisy state ρm and a set of error-boosted states. We performed numerical simulations for both subspaces so that we verified suppression of errors by orders of magnitude. Out protocol inherits positive aspects of previous error-agnostic QEM techniques while significantly overcoming their drawbacks., The control over the effect of noise is crucial for extracting reliable results from noisy quantum computers. Since current available quantum resources are not fully fault-tolerant, it is essential to develop practical quantum error mitigation (QEM) methods to compensate for unwanted computation errors. Here, we propose a novel error mitigation scheme: the generalized quantum subspace expansion method that can mitigate dominant errors in quantum computers. Exploitation of the substantially extended subspace allows us to efficiently mitigate the noise present in the spectra of a given Hamiltonian in a noise-agnostic way. We found two practical subspaces for practical error mitigation: the subspaces spanned by powers of the noisy state ρm and a set of error-boosted states. We performed numerical simulations for both subspaces so that we verified suppression of errors by orders of magnitude. Out protocol inherits positive aspects of previous error-agnostic QEM techniques while significantly overcoming their drawbacks.},
 title = {Generalized quantum subspace expansion method for error mitigation},
 year = {2021}
}