arXiv subjects

L. X. Cui

Publications and source records attributed to L. X. Cui.

3 recordsLinked to original sources

arXiv2025

Capacity-time Trade-off in Highly Reliable Quantum Memory

Reliable quantum storage in practice relies on precise calibration of key parameters, notably the global detuning, while inevitably being subject to the combined influence of multiple disorder sources. In this work, a comprehensive model for an Electromagnetically induced transparency (EIT) protocol is considered, in which coupling disorder and detuning disorder are incorporated simultaneously. After quantitatively analyzing the control dynamics, a highly precise phase-detuning relation to improve calibration accuracy is obtained. Building on this result, a Berry-phase-based control strategy is proposed to mitigate the degradation caused by the global detuning. We further reveal that there exists a joint effect simultaneously induced by different disorder sources, which can substantially reshape the decoherence. Finally, an effective notion of storage capacity is introduced and a general time-capacity relation is obtained, providing guidance for subsequent experimental optimization and device design.

quant-ph↗

arXiv2024

Quantum Analog of Vicsek Model for Active Matter

We propose a quantum model consisting of an ensemble of overdamped spin$-1/2$ particles with ferromagnetic couplings, driven by a radially homogeneous magnetic field. The spontaneous magnetization of the spin components breaks the $SO(3)$ (or $SO(2)$) symmetry, inducing an ordered phase of flocking. Our model converges to the Vicsek model in the classical limit and corresponds to the Toner-Tu model in the continuous limit. Our investigation not only elucidates the intrinsic connection between these two models, but also introduces new opportunities for exploring the mechanisms underlying flocking order and correlations at the quantum level, which maybe pave the way for a new field of research -- the quantum active matter.

quant-ph↗

arXiv2023

Quantum Reliability

Quantum technology has led to increasingly sophisticated and complex quantum devices. Assessing their reliability (quantum reliability) is an important issue. Although reliability theory for classical devices has been well developed in industry and technology, a suitable metric on quantum reliability and its loss has not been systematically investigated. Since reliability-loss depends on the process, quantum fidelity does not always fully depict it. This study provides a metric of quantum reliability by shifting the focus from state-distinguishing to trajectory-distinguishing. In contrast to the conventional notion of classical reliability, which is evaluated using probabilistic measurements of binary logical variables, quantum reliability is grounded in the quantum probability amplitude or wave function. This research provides a universal framework for reliability theory encompassing both classical and quantum devices. It offers a new perspective on quantum engineering by elucidating how intensely the real quantum process a device undergoes influences its performance.

quant-ph↗