Kuznetsov A S, Biermann K, Santos P V
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany.
Nat Commun. 2024 Jul 3;15(1):5343. doi: 10.1038/s41467-024-49610-5.
The harmonic modulation of coherent systems gives rise to a wealth of physical phenomena, e.g., the AC-Stark effect and Mollow triplets, with important implications for coherent control and frequency conversion. Here, we demonstrate a novel regime of temporal coherence in oscillators harmonically driven at extreme energy modulation amplitudes relative to the modulation quantum. The studies were carried out by modulating a confined exciton-polariton Bose-Einstein condensate (BEC) by an acoustic wave. Features of the new regime are the appearance, in the spectral domain, of a comb of resonances termed acceleration beats with energy spacing tunable by the modulation amplitude and, in the time domain, of temporal correlations at time scales much shorter than the acoustic period, which also depend on the modulation amplitude. These features are quantitatively accounted for by a theoretical framework, which associates the beats with accelerated energy-change rates during the harmonic cycle. These observations are underpinned by the high sensitivity of the BEC energy to the acoustic driving, which simultaneously preserves the BEC's temporal coherence. The acceleration beats are a general feature associated with accelerated energy changes: analogous features are thus also expected to appear under highly accelerated motion e.g., in connection with Cherenkov and Hawking radiation.
相干系统的谐波调制会引发大量物理现象，例如交流斯塔克效应和莫洛三重态，这对相干控制和频率转换具有重要意义。在此，我们展示了一种在振荡器中相对于调制量子处于极端能量调制幅度下受谐波驱动时的新型时间相干机制。这些研究是通过声波对受限的激子 - 极化子玻色 - 爱因斯坦凝聚体（BEC）进行调制来开展的。新机制的特征在于，在频谱域中出现了一系列被称为加速拍的共振梳齿，其能量间距可通过调制幅度进行调节；在时域中，出现了时间尺度远短于声学周期的时间相关性，且这种相关性也取决于调制幅度。这些特征可由一个理论框架进行定量解释，该框架将这些拍与谐波周期内加速的能量变化率联系起来。这些观测结果的基础是BEC能量对声学驱动的高灵敏度，同时这种驱动还能保持BEC的时间相干性。加速拍是与加速能量变化相关的一个普遍特征：因此，类似的特征预计也会在例如与切伦科夫辐射和霍金辐射相关的高度加速运动中出现。
