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Paper 1

Datacom-Agnostic Shortwave QKD for Short-Reach Links

Mariana Ferreira Ramos, Marie-Christine Slater, Michael Hentschel, Martin Achleitner, Hannes Hübel, Bernhard Schrenk

Year

2023

Journal

arXiv preprint

DOI

arXiv:2311.17591

arXiv

2311.17591

We investigate the co-existence of 852-nm and 1550-nm QKD with carrier-grade 4x25-Gb/s/$λ$ LANWDM over a short-reach interconnect. Shortwave QKD yields a higher key rate and is insensitive to Raman noise, as opposed to 1550-nm QKD.

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Paper 2

Fock space prethermalization and time-crystalline order on a quantum processor

Zehang Bao, Zitian Zhu, Yang-Ren Liu, Zixuan Song, Feitong Jin, Xuhao Zhu, Yu Gao, Chuanyu Zhang, Ning Wang, Yiren Zou, Ziqi Tan, Aosai Zhang, Zhengyi Cui, Fanhao Shen, Jiarun Zhong, Yiyang He, Han Wang, Jia-Nan Yang, Yanzhe Wang, Jiayuan Shen, Gongyu Liu, Yihang Han, Yaozu Wu, Jinfeng Deng, Hang Dong, Pengfei Zhang, Hekang Li, Zhen Wang, Chao Song, Chen Cheng, Rubem Mondaini, Qiujiang Guo, Biao Huang, H. Wang

Year

2025

Journal

arXiv preprint

DOI

arXiv:2510.24059

arXiv

2510.24059

Periodically driven quantum many-body systems exhibit a wide variety of exotic nonequilibrium phenomena and provide a promising pathway for quantum applications. A fundamental challenge for stabilizing and harnessing these highly entangled states of matter is system heating by energy absorption from the drive. Here, we propose and demonstrate a disorder-free mechanism, dubbed Fock space prethermalization (FSP), to suppress heating. This mechanism divides the Fock-space network into linearly many sparse sub-networks, thereby prolonging the thermalization timescale even for initial states at high energy densities. Using 72 superconducting qubits, we observe an FSP-based time-crystalline order that persists over 120 cycles for generic initial Fock states. The underlying kinetic constraint of approximately conserved domain wall (DW) numbers is identified by measuring site-resolved correlators. Further, we perform finite-size scaling analysis for DW and Fock-space dynamics by varying system sizes, which reveals size-independent regimes for FSP-thermalization crossover and links the dynamical behaviors to the eigenstructure of the Floquet unitary. Our work establishes FSP as a robust mechanism for breaking ergodicity, and paves the way for exploring novel nonequilibrium quantum matter and its applications.

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