arXiv subjects

Shiyu Guo

Publications and source records attributed to Shiyu Guo.

3 recordsLinked to original sources

arXiv2026

Layer-polarized Transport via Gate-defined 1D and 0D PN Junctions in Double Bilayer Graphene

We fabricate twisted double bilayer graphene devices with zero twist angle and a set of local top and bottom gates aligned perpendicularly to each other. A 1D PN junction can be electrostatically defined when the gate voltages applied to the top gates are the same but different on the bottom gates. Resistance peaks are observed at finite doping instead of at the charge neutrality points, exhibiting an unconventional broken-cross shape that arises from layer polarization of the P and N region, which can be further enhanced with finite magnetic fields. A 0D point junction (PJ) can be electrostatically defined by applying different gate voltages to the top and bottom gates, such that the P and N sides of the device are connected at a single point in the center of the device. As finite magnetic field B increases, the quantum Hall (QH) states are selectively brought into contact or away from each other depending on their layer polarization, leading to unconventional quantum oscillations which characterize the layer-polarized band-crossing. Our work provides new insights into understanding band-structure evolution and layer polarization in twisted bilayers and paves the way for new device functionality based on manipulating layer-polarized electronic states.

cond-mat.mes-hall↗

arXiv2026

Ferroelectric Quantum Point Contact in Twisted Transition Metal Dichalcogenides

In twisted transition metal dichalcogenides (tTMDs), atomic reconstruction gives rise to moir\'e domains with alternating ferroelectric polarization, whose domain size and overall electric dipole moment are tunable by an out-of-plane electric field. Previous transport measurements in Hall bar devices have successfully demonstrated the overall ferroelectric behavior of tTMDs from a collective ensemble of ferroelectric moir\'e domains. To locally probe a single ferroelectric moir\'e domain, we fabricate and study mesoscopic quantum transport via a gate-defined twisted molybdenum disulfide (tMoS2) quantum point contact (QPC). The local property of a single moir\'e domain is invulnerable to long-range disorder and twist-angle inhomogeneity, resulting in an unusually long conductance plateau with large electrical hysteresis. The comparison between local and global measurements confirms that antiferroelectricity can emerge from alternating polarization of individual ferroelectric domains. Using a QPC as a single charge sensor, we characterize the nature and time scale of different domain evolution mechanisms with single atomic dipole resolution. Our findings shed new light on the microscopic ferroelectric behavior and dynamics within a single tTMD moir\'e domain, paving the way toward more advanced ferroelectric quantum devices with tunable local Hamiltonian, such as ferroelectric tTMD quantum dots (QDs).

cond-mat.mes-hall↗

arXiv2024

AUITestAgent: Automatic Requirements Oriented GUI Function Testing

The Graphical User Interface (GUI) is how users interact with mobile apps. To ensure it functions properly, testing engineers have to make sure it functions as intended, based on test requirements that are typically written in natural language. While widely adopted manual testing and script-based methods are effective, they demand substantial effort due to the vast number of GUI pages and rapid iterations in modern mobile apps. This paper introduces AUITestAgent, the first automatic, natural language-driven GUI testing tool for mobile apps, capable of fully automating the entire process of GUI interaction and function verification. Since test requirements typically contain interaction commands and verification oracles. AUITestAgent can extract GUI interactions from test requirements via dynamically organized agents. Then, AUITestAgent employs a multi-dimensional data extraction strategy to retrieve data relevant to the test requirements from the interaction trace and perform verification. Experiments on customized benchmarks demonstrate that AUITestAgent outperforms existing tools in the quality of generated GUI interactions and achieved the accuracy of verifications of 94%. Moreover, field deployment in Meituan has shown AUITestAgent's practical usability, with it detecting 4 new functional bugs during 10 regression tests in two months.

cs.SE↗