arXiv subjects

Yuan-Zhuo Wang

Publications and source records attributed to Yuan-Zhuo Wang.

3 recordsLinked to original sources

arXiv2025

Weakly-Driven Quantum Walks for Memory-Constrained Pauli Channel Learning

Accurate characterization of quantum noise, exemplified by the Pauli channel, is a cornerstone for building fault-tolerant quantum computers. A recent protocol (PRX Quantum 6, 020323 (2025)) combining channel concatenation and quantum memory has achieved an exponential reduction in measurement complexity for Pauli channel estimation. This efficiency, however, hinges on using logarithmic quantum memory to suppress hypothesis test errors. In this work, we introduce a mechanism termed the ``weakly-driven quantum walk'' to mitigate the demand for high-quality quantum memory. By exploiting the distinct dynamical properties of quantum walks under biased versus unbiased driving, our algorithm lowers the quantum memory overhead to a constant order while preserving the exponential advantage in measurement complexity. By analogy with weak measurement, our introduced concept of ``weak driving'' preserves pointer coherence even when driven by classical probabilistic information, a principle that may inspire new approaches to similar quantum algorithm design and quantum sensing of weak signals in resource-constrained scenarios.

quant-ph↗

arXiv2025

Coherence in resonance fluorescence

Resonance fluorescence of a two-level emitter displays persistently anti-bunching irrespective of the excitation intensity, but inherits the driving laser's linewidth under weak monochromatic excitation. These properties are commonly explained in terms of two disjoined pictures, i.e., the emitter's single photon saturation or passively scattering light. Here, we propose a unified model that treats all fluorescence photons as spontaneous emission, one at a time, and can explain simultaneously both the spectral and correlation properties of the emission. We theoretically derive the excitation power dependencies, measurable at the single-photon incidence level, of the first-order coherence of the whole resonance fluorescence and super-bunching of the spectrally filtered, followed by experimental confirmation on a semiconductor quantum dot micro-pillar device. Furthermore, our model explains peculiar coincidence bunching observed in phase-dependent two-photon interference experiments. Our work provides an intuitive understanding of coherent light-matter interaction and may stimulate new applications.

quant-ph↗

arXiv2024

Experimental coherent-state quantum secret sharing with finite pulses

Quantum secret sharing (QSS) plays a significant role in multiparty quantum communication and is a crucial component of future quantum multiparty computing networks. Therefore, it is highly valuable to develop a QSS protocol that offers both information-theoretic security and validation in real optical systems under a finite-key regime. In this work, we propose a three-user QSS protocol based on phase-encoding technology. By adopting symmetric procedures for the two players, our protocol resolves the security loopholes introduced by asymmetric basis choice without prior knowledge of the identity of the malicious player. Kato's concentration inequality is exploited to provide security against coherent attacks with the finite-key effect. Moreover, the practicality of our protocol has been validated under a 30-dB channel loss with a transmission distance of 5-km fiber. Our protocol achieves secure key rates ranging from 432 to 192 bps by choosing different pulse intensities and basis selection probabilities. Offering enhanced security and practicality, our protocol stands as an essential element for the realization of quantum multiparty computing networks.

quant-ph↗