Ji-Ze Han

Robust Non-Adiabatic Holonomic Gating in Qutrits via Inverse-Engineered Pulse Shaping and Error Compensation

Jie Lu [1,2], Jie-Dong Huang [1], Yang Qian [1], Ying Yan [3,4,5], Zhi-Guo Huang, Ji-Ze Han

Abstract

Systematic control errors, specifically Rabi frequency fluctuations and frequency detuning, constitute a primary bottleneck for high-fidelity quantum gates across leading platforms. In this work, we present a robust pulse engineering framework for non-adiabatic holonomic quantum computing (NHQC) in qutrit systems, combining inverse engineering with time-dependent perturbation theory. We derive analytical conditions for pulse shaping that intrinsically eliminate second-order Rabi errors. Furthermore, our analysis reveals that second-order detuning errors are fundamentally linked to the accumulated population in the auxiliary excited state, making them impossible to eliminate in a single loop. To overcome this, we introduce a compensation pulse strategy that rigorously cancels these residual errors. Although this composite scheme doubles the gate duration, we demonstrate that the suppression of systematic errors yields a significant net gain in fidelity, achieving values exceeding 99.9% under realistic experimental imperfections ($ε=0.2$, $δ=2~\text{MHz}$). This framework provides a rigorous and experimentally feasible pathway for high-fidelity quantum control in superconducting circuits, trapped ions, and neutral atom systems.

High-Performance Microwave Frequency Standard Based on Sympathetically Cooled Ions

Hao-Ran Qin [1,2], Sheng-Nan Miao [1,3], Ji-Ze Han [1,3], Nong-Chao Xin [1,3], Yi-Ting Chen [1,3], J. W. Zhang [1,3], L. J. Wang [1,2,3]

Abstract

The ion microwave frequency standard is a candidate for the next generation of microwave frequency standard with the potential for very wide applications. The Dick effect and second-order Doppler frequency shift (SODFS) limit the performance of ion microwave frequency standards. The introduction of sympathetic cooling technology can suppress the Dick effect and SODFS and improve the stability and accuracy of the frequency standard. However, the sympathetically-cooled ion microwave frequency standard has seldom been studied before. This paper reports the first sympathetically-cooled ion microwave frequency standard in a Paul trap. Using laser-cooled ${}^{40}\mathrm{Ca}^{+}$ as coolant ions, ${}^{113}\mathrm{Cd}^{+}$ ion crystal is cooled to below 100 mK and has a coherence lifetime of over 40 s. The short-term frequency stability reached $3.48 \times 10^{-13}/τ^{1/2}$, which is comparable to that of the mercury ion frequency standard. Its uncertainty is $1.5\times 10^{-14}$, which is better than that of directly laser-cooled cadmium ion frequency standard.