arXiv subjects

Kerui Li

Publications and source records attributed to Kerui Li.

10 recordsLinked to original sources

arXiv2026

Branch-resolved Pauli-block spectroscopy of residual conditional phase in two-qubit gates

Recent progress in quantum physics and quantum technologies is driving quantum computing from the noisy intermediate-scale (NISQ) era toward fault-tolerant operation. High-precision control of two-qubit gates is among the most critical requirements in this transition and hinges on accurate two-qubit calibration. For controlled-phase and CZ-style operations, the residual conditional phase (the nonlocal ZZ-type deviation after local compensation) is weakly resolved at leading order in average infidelity and randomized benchmarking, and repeated Ramsey amplification does not reliably isolate it from ordinary target detuning, SPAM errors, and contrast loss in long sequences. We introduce branch-resolved Pauli-block spectroscopy to estimate the per-cycle residual ZZ-rotation angle theta_c with its sign, from which the controlled-phase residual follows by a fixed convention. The protocol repeats a fixed probe for N cycles, measures the closed Pauli block IX, IY, ZX, and ZY, and forms branch coherences C+ and C- conditioned on the control qubit; theta_c splits the two branch phase slopes in opposite directions, while local target phase beta_c shifts them together. An echoed-cycle variant suppresses removable local terms while preserving the nonlocal contribution. Numerical simulations with injected theta_c, detuning, damping, and SPAM confirm unbiased signed readout where scalar-sector alternatives fail and distinguish opposite-sign errors at equal infidelity. On one superconducting cloud qubit-coupler pair, a pulse-level calibration closed loop shows near-linear injection, preserved branch contrast, and tracking of the native residual conditional phase through one iteration. The approach yields a low-overhead, signed per-cycle estimate of residual conditional phase that standard fidelity benchmarks underresolve at leading order.

quant-ph↗

arXiv2026

StableIDM: Stabilizing Inverse Dynamics Model against Manipulator Truncation via Spatio-Temporal Refinement

Inverse Dynamics Models (IDMs) map visual observations to low-level action commands, serving as central components for data labeling and policy execution in embodied AI. However, their performance degrades severely under manipulator truncation, a common failure mode that makes state recovery ill-posed and leads to unstable control. We present StableIDM, a spatio-temporal framework that refines features from visual inputs to stabilize action predictions under such partial observability. StableIDM integrates three complementary components: (1) auxiliary robot-centric masking to suppress background clutter, (2) Directional Feature Aggregation (DFA) for geometry-aware spatial reasoning, which extracts anisotropic features along directions inferred from the visible arm and (3) Temporal Dynamics Refinement (TDR) to smooth and correct predictions via motion continuity. Extensive evaluations validate our approach: StableIDM improves strict action accuracy by 12.1% under severe truncation on the AgiBot benchmark, and increases average task success by 9.7% in real-robot replay. Moreover, it boosts end-to-end grasp success by 11.5% when decoding video-generated plans, and improves downstream VLA real-robot success by 17.6% when functioning as an automatic annotator. These results demonstrate that StableIDM provides a robust and scalable backbone for both policy execution and data generation in embodied artificial intelligence.

cs.RO↗

arXiv2026

VAG: Dual-Stream Video-Action Generation for Embodied Data Synthesis

Recent advances in robot foundation models trained on large-scale human teleoperation data have enabled robots to perform increasingly complex real-world tasks. However, scaling these systems remains difficult because collecting task-specific demonstrations is expensive and labor-intensive. Synthetic data, especially generated videos, offer a promising direction, but existing World Models (WMs) are not directly suitable for policy learning since they do not provide paired action trajectories. World-Action (WA) models partially address this by predicting actions with visual outputs, yet often lack strong video-action alignment, while two-stage pipelines that generate video first and then infer actions introduce inefficiency and error accumulation. To address these limitations, we propose VAG, a unified flow-matching-based dual-stream framework that jointly generates video and action under visual and language conditioning. By synchronizing denoising in both branches and using an adaptive 3D pooling mechanism to transfer compact global video context to the action branch, VAG improves cross-modal consistency during generation. Across both simulated and real-world settings, VAG produces aligned video-action pairs with competitive prediction quality, supports executable trajectory replay, and provides useful synthetic pretraining data that improves downstream policy generalization, indicating its potential as a practical world-action model for embodied data synthesis.

cs.RO↗

arXiv2025

GigaWorld-0: World Models as Data Engine to Empower Embodied AI

World models are emerging as a foundational paradigm for scalable, data-efficient embodied AI. In this work, we present GigaWorld-0, a unified world model framework designed explicitly as a data engine for Vision-Language-Action (VLA) learning. GigaWorld-0 integrates two synergistic components: GigaWorld-0-Video, which leverages large-scale video generation to produce diverse, texture-rich, and temporally coherent embodied sequences under fine-grained control of appearance, camera viewpoint, and action semantics; and GigaWorld-0-3D, which combines 3D generative modeling, 3D Gaussian Splatting reconstruction, physically differentiable system identification, and executable motion planning to ensure geometric consistency and physical realism. Their joint optimization enables the scalable synthesis of embodied interaction data that is visually compelling, spatially coherent, physically plausible, and instruction-aligned. Training at scale is made feasible through our efficient GigaTrain framework, which exploits FP8-precision and sparse attention to drastically reduce memory and compute requirements. We conduct comprehensive evaluations showing that GigaWorld-0 generates high-quality, diverse, and controllable data across multiple dimensions. Critically, VLA model (e.g., GigaBrain-0) trained on GigaWorld-0-generated data achieve strong real-world performance, significantly improving generalization and task success on physical robots without any real-world interaction during training.

cs.CV↗

arXiv2021

Dynamic Response and Stability Margin Improvement of Wireless Power Receiver Systems via Right-Half-Plane Zero Elimination

The series-series compensation topology is widely adopted in many wireless power transfer applications. For such systems, their wireless power receiver part typically involves a DC-DC converter with front-stage full-bridge diode rectifier, to process the high-frequency transmitted AC power into a DC output voltage for the load. It is recently reported that the current source nature of the series-series compensation will introduce right-half-plane (RHP) zeros into the small-signal transfer functions of the DC-DC converter of the wireless power receiver, which will severely affect the stability and dynamic response of the system. To resolve this issue, in this paper, it is proposed to adopt a different rectifier configuration for the system such that the input current to the DC-DC converter becomes controllable to eliminate the presence of RHP zeros of the small-signal transfer functions of the system. This rectifier can be applied to different wireless power receivers using the buck, buck-boost, or boost converters. As compared with the original wireless power receivers, the modified ones feature minimum-phase characteristics and hence ease the design of compensator. Theoretical and experimental results are provided. The comparative experimental results verify the elimination of the RHP zero, improved dynamic responses of reference tracking and against load disturbances, and a larger stability margin.

eess.SP↗

arXiv2021

Highly-Efficient Single-Switch-Regulated Resonant Wireless Power Receiver with Hybrid Modulation

In this paper, a highly-efficient single-switch-regulated resonant wireless power receiver with hybrid modulation is proposed. To achieve both high efficiency and good output voltage regulation, phase shift and pulse width hybrid modulation are simultaneously applied. The soft switching operation in this topology is achieved by the cycle-by-cycle phase shift adjustment between the input current and the gate drive signal and also attributed to the reactive components such as the series-compensated secondary coil and the parasitic capacitor of the active switch . The soft switching operation also leads to high efficiency and low EMI. By adjusting the duty ratio of the switch, tight regulation of the output voltage can be attained. The steady-state and dynamic models of the resonant receiver with hybrid modulation are analytically derived in order to properly design the feedback controller. An experimental setup of a two-coil wireless power transfer system, including the hardware prototype of the proposed receiver, is constructed for experimental verification. The experimental results show the effectiveness of the soft-switching operation in the receiver with high efficiency while maintaining good regulation of the output voltage, regardless of line and load variations.

eess.SY↗

arXiv2020

On Effect of Right-Half-Plane Zero Present in Buck Converters with Input Current Source in Wireless Power Receiver Systems

In wireless power receiver systems, the buck converter is widely used to step down the higher rectified voltage derived from the wireless receiver coil, to a lower output voltage for the immediate battery charging process. In this work, the presence and effect of the right-half-plane (RHP) zeros found in the small-signal inductor-current-to-duty-ratio and output-voltage-to-duty ratio transfer functions of the buck converter in the wireless power receiver system on the control performance, are investigated. It is found and mathematically proved that the RHP zeros are introduced by the current source nature of the system attributed to the series-series compensation and finite DC-link capacitance. The RHP zero not only results in non-monotonic open-loop dynamic response but also complicates the design of feedback control and causes potential closed-loop instability. Theoretical and experimental results are provided to validate the presence of the RHP zeros and their effect on open-loop and closed-loop dynamic responses.

eess.SY↗

arXiv2020

On Beat Frequency Oscillation of Two-Stage Wireless Power Receivers

Two-stage wireless power receivers, which typically include an AC-DC diode rectifier and a DC-DC regulator, are popular solutions in low-power wireless power transfer applications. However, the interaction between the rectifier and the regulator may introduce beat frequency oscillation on both the DC-link and output capacitors. In this paper, the cause of the beat frequency oscillation and its related issues are investigated with the corresponding design solution on alleviating the oscillation discussed. Theoretical and experimental results verifying the presence of beat frequency oscillation in the two-stage wireless receiver system are provided. Our study shows that the beat frequency oscillation can be significantly alleviated if appropriate design solutions are applied.

eess.SY↗

arXiv2019

Single-Switch-Regulated Resonant WPT Receiver

A single-switch-regulated wireless power transfer (WPT) receiver is presented in this letter. Aiming at low-cost applications, the system involves only a single-switch class-E resonant rectifier, a frequency synchronization circuit, and a microcontroller. The number of power semiconductor devices required in this circuit is minimal. Only one active switch is used and no diode is required. As a single-switch solution, this simplifies circuit implementation, improves reliability, and lowers hardware cost. The single-switch resonant rectifier provides a relatively constant quasi-sinusoidal voltage waveform to pick up the wireless power from the receiver coil. Due to the resonant nature of the rectifier, ZVS turn on and turn off are achieved. The steady-state analysis and discussions on the component sizing and the control design are provided. A prototype is built and experimental works are performed to verify the features.

eess.SY↗

arXiv2019

Single-Stage Regulated Resonant WPT Receiver with Low Input Harmonic Distortion

Resonant rectifier topologies would be a promising candidate for achieving simple, compact, and reliable single-stage wireless power transfer (WPT) receiver if not for the lack of good DC regulation capability. This paper investigates the problems that prevent the feasibility of single-stage DC regulation in resonant rectifier topologies. A possible solution is the proposed differential resonant rectifier topology, of which the rectifier is designed to have a relatively constant AC voltage, and that phase shift control is used to achieve relatively good output regulation. Design considerations on the reactive component sizing, magnetic component design, frequency and phase synchronization, small signal modelling, and closed-loop feedback control design, are discussed. Experimental results verified that the proposed WPT receiver system can achieve single-stage AC rectification and DC regulation while attaining the key features of low harmonic distortion in its AC output voltage, continuous DC current, and zero-voltage-switching (ZVS) operation over a wide operating range.

eess.SY↗