近日，清华大学丁世谦团队研究了连续波窄线宽真空紫外激光源。相关论文于2026年2月11日发表在《自然》杂志上。

钍-229在约148.4纳米处发生的极低能同质异能跃迁，为相干核操控与核时钟的实现提供了独特机遇。近期进展——特别是将大块钍-229核群掺入透明晶体，以及脉冲真空紫外激光器的发展——已使该跃迁的初步激光光谱研究成为可能。然而，由于缺乏高功率、窄线宽的真空紫外激光器，相干核操控始终未能实现。

研究组介绍并报道了一种通过镉蒸气中四波混频产生的148.4纳米连续波激光器。该光源输出功率逾100纳瓦，预期线宽远低于100赫兹，且支持宽波长调谐。这标志着在190纳米以下所有先前单频激光器线宽的基础上，实现了五个数量级的精度跃升。

研究组发展了一种空间分辨零差探测技术，对四波混频诱发的相位噪声施加了严格上限，从而证实了亚赫兹真空紫外激光线宽的可行性。该工作攻克了基于钍-229的核时钟所面临的核心挑战，并建立了一个宽调谐、超窄线宽的激光平台，为量子信息科学、凝聚态物理²?及高分辨率真空紫外光谱学²?等领域的潜在应用开辟道路。

附：英文原文

Title: Continuous-wave narrow-linewidth vacuum ultraviolet laser source

Author: Xiao, Qi, Penyazkov, Gleb, Li, Xiangliang, Huang, Beichen, Bu, Wenhao, Shi, Juanlang, Shi, Haoyu, Liao, Tangyin, Yan, Gaowei, Tian, Haochen, Li, Yixuan, Li, Jiatong, Lu, Bingkun, You, Li, Lin, Yige, Mo, Yuxiang, Ding, Shiqian

Issue&Volume: 2026-02-11

Abstract: The exceptionally low-energy isomeric transition in 229Th at around 148.4nm (refs.1,2,3,4,5,6) offers a unique opportunity for coherent nuclear control and the realization of a nuclear clock7,8. Recent advances, most notably the incorporation of large ensembles of 229Th nuclei in transparent crystals6,9,10,11 and the development of pulsed vacuum ultraviolet (VUV) lasers12,13,14, have enabled initial laser spectroscopy of this transition15,16,17. However, the lack of an intense, narrow-linewidth VUV laser has precluded coherent nuclear manipulation8,18. Here we introduce and report a continuous-wave (CW) laser at 148.4nm, generated by means of four-wave mixing (FWM)19 in cadmium vapour. The source delivers more than 100nW of power with a projected linewidth well below 100Hz and supports broad wavelength tunability. This represents a five-orders-of-magnitude improvement in linewidth over all previous single-frequency lasers below 190nm (refs.12,13,14,20). We develop a spatially resolved homodyne technique that places a stringent upper bound on FWM-induced phase noise, thereby supporting the feasibility of sub-hertz VUV linewidths. Our work addresses the central challenge towards a 229Th-based nuclear clock and establishes a widely tunable, ultranarrow-linewidth laser platform for potential applications across quantum information science21,22,23,24, condensed-matter physics25 and high-resolution VUV spectroscopy26.

DOI: 10.1038/s41586-026-10107-4

Source: https://www.nature.com/articles/s41586-026-10107-4