Strong quantum interferences in frequency up-conversion towards short vacuum-ultraviolet radiation pulses
Strong quantum interferences in frequency up-conversion towards short vacuum-ultraviolet radiation pulses
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DOI：
10.1103/physreva.89.063804
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发表时间：
2014-06-10
影响因子：
2.9
通讯作者：
Halfmann, Thomas
中科院分区：
文献类型：
--
作者：
Ackermann, Patric;Scharf, Alexander;Halfmann, Thomas
我们目前的实验数据量子干涉共振增强频率上转换向真空紫外光谱制度。这个过程是由超短（皮秒）激光脉冲在氙原子中驱动的。我们使用两个同时的频率转换途径，通过激发中间态，即，基波波长的五次谐波产生和基波与其二次谐波波长的两个光子的四波混频。两种转换途径都产生102 nm的辐射。这两条路径的干涉取决于基波和二次谐波的相对相位。通过适当地选择相位，我们得到相长干涉（导致提高的转换效率）或相消干涉（导致降低的转换效率）。总的转换产率显示出非常明显的建设性和破坏性的量子干涉与约90%的可见性。一个稳定和高精度的相位控制设置可以实现超过260个振荡周期的强量子干涉。在实验的扩展中，与频率转换同时，我们还监测激光诱导荧光，作为对激发中间态的激发概率的测量。此外，在激发概率，我们观察到强的量子干涉。作为一个有趣的功能，一个小的相位滞后之间发生的量子干涉模式的频率转换和人口转移。这是由于在频率转换期间获得的附加原子相位。
We present experimental data on quantum interferences in resonantly enhanced frequency up-conversion towards the vacuum-ultraviolet spectral regime. The process is driven in xenon atoms by ultrashort (picosecond) laser pulses. We use two simultaneous frequency conversion pathways via an excited intermediate state, i.e., fifth harmonic generation of the fundamental wavelength and four-wave mixing of the fundamental and two photons of its second harmonic wavelength. Both conversion pathways yield radiation at 102 nm. The two pathways interfere, depending on the relative phase of the fundamental and second harmonic. By appropriate choice of the phase we get constructive interference (resulting in increased conversion efficiency) or destructive interference (resulting in reduced conversion efficiency). The total conversion yield shows very pronounced constructive and destructive quantum interference with a visibility of roughly 90%. A stable and highly accurate phase control setup enables such strong quantum interferences for more than 260 oscillation cycles. In an extension of the experiment, simultaneously to frequency conversion we also monitor laser-induced fluorescence as a measure for the excitation probability to the excited intermediate state. Also, in the excitation probability we observe strong quantum interferences. As an interesting feature, a small phase lag occurs between the quantum interference patterns of frequency conversion and population transfer. This is due to an additional atomic phase acquired during frequency conversion.