Max Kneiß | Searcharxiv

arXiv2026

Grover Search with Semiconductor Spin Qubits at Ambient Conditions

Grover's algorithm is executed on a commercial quantum computer based on nitrogen-vacancy centers in diamond operating under ambient conditions, achieving fidelities up to $99.98\,\%$. Within a $N=8$ search space of three solid-state nuclear spin qubits, the measured success probabilities of finding a single or two marked states are $(77.3 \pm 3.4)\,\%$ and $(87.0 \pm 4.2)\,\%$, respectively. These values surpass published results for superconducting qubits or any quantum computer operating at room temperature. In addition, the paper also details the calibrated fidelities of the implemented universal gate set.

quant-ph↗

arXiv2025

Decoupling Composition and Band Gap in $κ$-Ga$_2$O$_3$ Heterostructures via STEM-EELS

High-resolution mapping of electronic properties at oxide heterointerfaces remains challenging due to probe delocalization and overlapping signals. In this work, we employ monochromated, probe-corrected scanning transmission electron microscopy combined with electron energy-loss spectroscopy (STEM-EELS) to resolve band gap variations across $κ$-Ga$_2$O$_3$-based multilayers with nanometer-scale precision. A custom automated quantitative-based EELS analysis framework enabled automated band gap fitting and visualization, ensuring reproducibility and high spatial resolution. By optimizing acquisition parameters and quantifying inelastic delocalization, we demonstrate reliable extraction of band gap excitations from layers only a few nanometers thick. For heterostructures grown on ITO templates, strain at defect-free interfaces induces a gradual band gap transition from $5.08~\mathrm{eV}$ to $4.28~\mathrm{eV}$ over $\sim 10~\mathrm{nm}$, despite an abrupt compositional change. In contrast, ZnO-based templates introduce structural defects that relieve strain, yielding band gaps consistent with composition. These results establish STEM-EELS as a powerful tool for nanoscale electronic characterization and highlight the dominant role of interfacial strain over composition in governing local band structure.

cond-mat.mtrl-sci↗