arXiv subjects

Gangxi Wang

Publications and source records attributed to Gangxi Wang.

3 recordsLinked to original sources

arXiv2026

Geometry-Resolved Projection of RF Imbalance to Ion Micromotion in a Same-Phase Dual-RF Blade Trap

Common-mode metrics of a high-$Q$ helical resonator do not determine the residual ion-side field in a dual-electrode drive. We combine a two-node differential RF model with single-electrode finite-element bases to obtain a computation-only, geometry-resolved projection for a same-phase blade trap. For a 3.5 pF external load per branch, the model gives a total effective branch capacitance of 7.640 pF and an HWHM-equivalent full branch-difference scale of 12.7 fF at $Q_{\mathrm{loaded}}=600$. The seven-segment geometry gives center and axial-RMS differential field coefficients of 640 V m$^{-1}$ and 635 V m$^{-1}$ per differential peak volt. A representative 10 fF mismatch with an effective 0.1 pF balance scale projects to 44.5/44.1 nm center/RMS $^{171}\mathrm{Yb}^{+}$ micromotion at 100 V common peak voltage. Supplementary thermal, bypass-admittance, and tested numerical cases characterize model sensitivity. All reported displacements are projections; no RF-bench or ion-side validation is claimed.

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arXiv2026

Boundary-Phase Control of Sequentially Addressed Trapped-Ion ZZ Interactions

Motion-mediated trapped-ion interactions commonly coordinate state-dependent forces on both target ions. Sequential optical access reduces the number of concurrent target channels but makes the relative phase between disjoint force windows a control variable. We derive a complex near-resonant description in which each window generates a displacement vector and ordered symplectic products between vectors on different ions produce the ZZ phase. Only relative boundary phases affect this area; a common phase shift is a gauge transformation. Building on the experimental precedent for alternating single-ion addressing, we develop matched-envelope phase and contrast controls that isolate this boundary-phase dependence without target-window overlap or hidden force in the dark gaps. The analysis separates phase generation from differential closure, projector-common motion, deterministic local-Z phases, spectator coupling, and control-parameter transfer. A conditional-Ramsey sequence gives continuous and reset contrasts of 0.998 and 0.996, with a reset-induced phase separation of 0.581 rad modulo $\pi/2$. In the representative comparison, sequential control uses fewer concurrent target channels but greater normalized force action than independently calibrated simultaneous control. All results are model-level estimates within the stated Lamb-Dicke, rotating-wave, and apparatus-input limits.

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arXiv2024

Observation of quantum superposition of topological defects in a trapped ion quantum simulator

Topological defects are discontinuities of a system protected by global properties, with wide applications in mathematics and physics. While previous experimental studies mostly focused on their classical properties, it has been predicted that topological defects can exhibit quantum superposition. Despite the fundamental interest and potential applications in understanding symmetry-breaking dynamics of quantum phase transitions, its experimental realization still remains a challenge. Here, we report the observation of quantum superposition of topological defects in a trapped-ion quantum simulator. By engineering long-range spin-spin interactions, we observe a spin kink splitting into a superposition of kinks at different positions, creating a ``Schrodinger kink'' that manifests non-locality and quantum interference. Furthermore, by preparing superposition states of neighboring kinks with different phases, we observe the propagation of the wave packet in different directions, thus unambiguously verifying the quantum coherence in the superposition states. Our work provides useful tools for non-equilibrium dynamics in quantum Kibble-Zurek physics.

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