Journal Article

FZJ-2025-01837

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Coherent and non-unitary errors in ZZ-generated gates

Müller, T. (Corresponding author) ; Stollenwerk, T.FZJ* ; Headley, D. ; Epping, M. ; Wilhelm, F. K.FZJ*

2025
IOP Publishing Philadelphia, PA

This record in other databases:  

Please use a persistent id in citations: doi:10.1088/2058-9565/ad9be2  doi:10.34734/FZJ-2025-01837

Abstract: Variational algorithms such as the quantum approximate optimization algorithm have attracted attention due to their potential for solving problems using near-term quantum computers. The ZZ interaction typically generates the primitive two-qubit gate in such algorithms applied for a time, typically a variational parameter, γ. Different compilation techniques exist with respect to the implementation of two-qubit gates. Due to the importance of the ZZ-gate, we present an error analysis comparing the continuous-angle controlled phase gate (CP) against the fixed angle controlled Z-gate (CZ). We analyze both techniques under the influence of coherent over-rotation and depolarizing noise. We show that CP and CZ compilation techniques achieve comparable ZZ-gate fidelities if the incoherent error is below 0.03% and the coherent error is below 0.8%. Thus, we argue that for small coherent and incoherent error a non-parameterized two-qubit gate such as CZ in combination with virtual Z decomposition for single-qubit gates could lead to a significant reduction in the calibration required and, therefore, a less error-prone quantum device. We show that above a coherent error of 0.04π (2%), the CZ gate fidelity depends significantly on γ.

---

Contributing Institute(s):

1. Quantum Computing Analytics (PGI-12)

Research Program(s):

1. BMBF 13N16149 - QSolid (BMBF-13N16149) (BMBF-13N16149)
2. 5221 - Advanced Solid-State Qubits and Qubit Systems (POF4-522) (POF4-522)

Appears in the scientific report 2025

---

Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

---