Quantum coherent optical phase modulation in an ultrafast transmission electron microscope
Quantum coherent optical phase modulation in an ultrafast transmission electron microscope
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DOI：
10.1038/nature14463
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发表时间：
2015-05-14
期刊：
影响因子：
64.8
通讯作者：
Ropers, Claus
中科院分区：
文献类型：
--
作者：
Feist, Armin;Echternkamp, Katharina E.;Ropers, Claus
光量子系统的相干操纵预计将成为未来信息和通信技术的基石，包括量子计算和密码学（1）。光学相位到量子波函数上的转移是相干相互作用的定义方面，并且形成量子态制备、同步和计量学的基础。原子和分子附近的光相位调制电子态对于阿秒科学技术是必不可少的，包括产生极紫外脉冲和轨道层析成像（2，3）。相比之下，高能自由电子束的量子相干相位调制尚未得到证实，尽管它承诺直接获得超快成像和光谱学，并在阿秒尺度上定制电子脉冲。在这里，我们展示了相干量子态操纵的自由电子种群的电子显微镜光束。我们采用超短电子脉冲与光学近场（4-9）的相互作用来诱导电子动量态的布居中的拉比振荡，观察到作为光学驱动场的函数。获得了与等拉比多能级量子阶梯的标度非常一致的结果（10），代表了光驱动的“量子行走”（5）在动量空间（11）中相干重塑电子密度的观察。我们注意到，在相互作用之后，光学产生的动量态叠加演化成阿秒电子脉冲串。我们的研究结果揭示了量子控制的电子密度的精确结构的潜力，可能的应用范围从超快电子光谱学和显微镜加速器科学和自由电子激光器。
Coherent manipulation of quantum systems with light is expected to be a cornerstone of future information and communication technology, including quantum computation and cryptography(1). The transfer of an optical phase onto a quantum wavefunction is a defining aspect of coherent interactions and forms the basis of quantum state preparation, synchronization and metrology. Light-phase-modulated electron states near atoms and molecules are essential for the techniques of attosecond science, including the generation of extreme-ultraviolet pulses and orbital tomography(2,3). In contrast, the quantum-coherent phase-modulation of energetic free-electron beams has not been demonstrated, although it promises direct access to ultrafast imaging and spectroscopy with tailored electron pulses on the attosecond scale. Here we demonstrate the coherent quantum state manipulation of free-electron populations in an electron microscope beam. We employ the interaction of ultrashort electron pulses with optical nearfields(4-9) to induce Rabi oscillations in the populations of electron momentum states, observed as a function of the optical driving field. Excellent agreement with the scaling of an equal-Rabi multi-level quantum ladder is obtained(10), representing the observation of a light-driven 'quantum walk'(5) coherently reshaping electron density in momentum space(11). We note that, after the interaction, the optically generated superposition of momentum states evolves into a train of attosecond electron pulses. Our results reveal the potential of quantum control for the precision structuring of electron densities, with possible applications ranging from ultrafast electron spectroscopy and microscopy to accelerator science and free-electron lasers.