Single-Copy Certification of Two-Qubit Gates Without Entanglement

Yujun Choi, Tanmay Singal, Young Wook Cho, Sang Wook Han, Kyunghwan Oh, Sung Moon, Yong Su Kim, Joonwoo Bae

Research output: Contribution to journalArticlepeer-review


A quantum state transformation can be generally approximated by single- and two-qubit gates. This, however, does not hold with noisy intermediate-scale quantum technologies due to the errors appearing in the gate operations, where errors of two-qubit gates such as controlled-not and swap operations are dominated. In this work we present a cost efficient single-copy certification for a realization of a two-qubit gate in the presence of depolarization noise, where we aim to identify if the realization is noise free, or not. We show that entangled resources such as entangled states and a joint measurement are not necessary for the purpose, i.e., a noise-free two-qubit gate is not needed to certify an implementation of a two-qubit gate. We present a proof-of-principle demonstration with photonic qubits.

Original languageEnglish
Article number044046
JournalPhysical Review Applied
Issue number4
Publication statusPublished - 2022 Oct

Bibliographical note

Funding Information:
This work was supported by Samsung Research Funding & Incubation Center of Samsung Electronics (Project No. SRFC-TF2003-01) and the KIST Institutional Programs (2E31021).

Publisher Copyright:
© 2022 American Physical Society.

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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