arXiv subjects

Dounan Du

Publications and source records attributed to Dounan Du.

3 recordsLinked to original sources

arXiv2025

Telecom-compatible cross-band quantum memory via dual photon modes dark-state polaritons

Quantum memories are essential components of quantum networks, enabling synchronization, quantum repeaters, and long-distance entanglement distribution. Most ensemble-based realizations rely on dark-state polaritons (DSPs) in $Λ$-type systems that operate at near-infrared wavelengths, such as 795 nm in $^{87}$Rb, far from the telecom band where long fiber transmission is optimal. Here we identify a DSP in $^{87}$Rb that coherently couples two photonic modes at 795 nm and 1324 nm through a shared spin-wave coherence. We derive its field operator and group velocity, extending the Fleischhauer-Lukin model to a dual-wavelength regime, and formulate a memory protocol enabling bidirectional storage and retrieval between the two modes. Numerical simulations of the full six-level dynamics confirm two-way storage and retrieval for both same-mode and cross-mode operation between the two wavelengths. The results demonstrate a dual-wavelength memory that unifies node-band and telecom-band operation within a single ensemble, providing a potential route toward frequency-conversion-free quantum-network interfaces.

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arXiv2025

Learning spatially structured open quantum dynamics with regional-attention transformers

Simulating the dynamics of open quantum systems with spatial structure and external control is an important challenge in quantum information science. Classical numerical solvers for such systems require integrating coupled master and field equations, which is computationally demanding for simulation and optimization tasks and often precluding real-time use in network-scale simulations or feedback control. We introduce a regional attention-based neural architecture that learns the spatiotemporal dynamics of structured open quantum systems. The model incorporates translational invariance of physical laws as an inductive bias to achieve scalable complexity, and supports conditioning on time-dependent global control parameters. We demonstrate learning on two representative systems: a driven dissipative single qubit and an electromagnetically induced transparency (EIT) quantum memory. The model achieves high predictive fidelity under both in-distribution and out-of-distribution control protocols, and provides substantial acceleration up to three orders of magnitude over numerical solvers. These results demonstrate that the architecture establishes a general surrogate modeling framework for spatially structured open quantum dynamics, with immediate relevance to large-scale quantum network simulation, quantum repeater and protocol design, real-time experimental optimization, and scalable device modeling across diverse light-matter platforms.

quant-ph↗

arXiv2024

A long-distance quantum-capable internet testbed

Building a Quantum Internet requires the development of innovative quantum-enabling networking architectures that integrate advanced communication systems with long-distance quantum communication hardware. Here, we present the implementation of a quantum-enabled internet prototype using a novel physics-centric stack-based quantum network paradigm to govern the dynamics of multiple light-matter Hamiltonians across distant nodes. We demonstrate this concept using a deployed large-scale intercity quantum network connecting laboratories at Stony Brook University and the Brookhaven National Laboratory. This network facilitates a fundamental long-distance quantum network service -that of high-visibility Hong-Ou-Mandel interference of telecom quantum states generated in two independent, telecom-compatible quantum light-matter interfaces separated by a distance of 158 km.

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