When travelling in outer space, what is necessary equipment for you? The answer should be an extremely accurate clock, which is useful for checking time and navigation. Then, the best candidate should be optical lattice clock – the most accurate time-frequency measurement device [1].
With help of the laser cooling technique, the ultra-cold atom can be trapped in the optical lattice constructed by counterpropagating laser beams. Then, the atoms can provide high-precision time frequency. Usually, the system is set along the direction of the gravity, so that the inter-site quantum tunnelling can be suppressed, especially in the shallow optical lattice [2-3]. However, weak gravity in outer space!
Recently, scientists from CQU and NTSC shake the optical lattice clock by periodically modulating the frequency of the laser beam [4]. Counterintuitively, the quantum tunnelling is strongly suppressed due to the dynamical localization mechanism. Then, the wide broad spectral line is deformed into a sharp peak with Hz-level linewidth, which is the first step of building clock. Although far from a real Floquet optical lattice clock, it still can be taken as an alternative route towards outer space.
Reference:
[1] A. D. Ludlow, M. M. Boyd, J. Ye, E. Peik, and P. O. Schmidt Rev. Mod. Phys. 87, 637 (2015).
[2] T. Bothwell, et al, Nature 602, 420–424, (2022)
[3] X. Zheng, et al, Nature 602, 425–430 (2022)
[4] X.-T. Lu, et al, Phys. Rev. Lett. 128, 073603 (2022)
