Phase-Fidelity-Aware Truncated Quantum Fourier Transform for Scalable Phase Estimation on NISQ Hardware

Quantum Physics [Submitted on 7 Apr 2026] Phase-Fidelity-Aware Truncated Quantum Fourier Transform for Scalable Phase Estimation on NISQ Hardware Akoramurthy B, Surendiran.B Quantum phase estimation~(QPE) is central to numerous quantum algorithms, yet its standard implementation demands an \calO(m^{2})$\calO(m^{2})$-gate quantum Fourier transform~(QFT) on m control qubits-a prohibitive overhead on near-term noisy intermediate-scale quantum (NISQ) devices. We introduce the \emph{Phase-Fidelity-Aware Truncated QFT} (PFA-TQFT), a family of approximate QFT circuits parameterised by a truncation depth~d that omits controlled-phase rotations below a hardware-calibrated fidelity threshold~\eps. Our central result establishes \TV(P_{\varphi},P_{\varphi}^{d})\leq\pi(m{-}d)/2^{d}, showing that for d=\calO(\log m) circuit size collapses from \calO(m^{2}) to \calO(m\log m) while estimation error grows by at most \calO(2^{-d}). We characterise \dstar=\Floor{\log_{2}(2\pi/\eps_{2q})} directly from native gate fidelities, demonstrating 31.3 -43.7\% at m = 30, gate-count reduction on IBM Eagle/Heron and IonQ~Aria with negligible accuracy loss. Numerical experiments on the transverse-field Ising model confirm all theoretical predictions and reveal a \emph{noise-truncation synergy}: PFA-TQFT outperforms full QFT under NISQ noise \eps_{2q}\gtrsim 2\times10^{-3}. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2604.05456 [quant-ph]   (or arXiv:2604.05456v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2604.05456 Focus to learn more Submission history From: Surendiran B [view email] [v1] Tue, 7 Apr 2026 05:39:21 UTC (1,650 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-04 References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)