Extremely nonlinear spectroscopy based on high-order-harmonic generation has become a powerful investigation method for attosecond dynamics in gas and solid targets. In particular, the phase of harmonic emission was shown to carry profound insight into atomic and molecular structure and dynamics. However, current techniques offer phase measurements only along specific directions, thus providing partial characterization. Here we report on a new approach combining optical and quantum interferometers measuring along two dimensions the intensity and phase of harmonic emission from aligned molecules in the exact same experimental conditions. This two-dimensional cartography technique measures the phase with no arbitrary offset and no uncertainty on its sign. Measurements along different dimensions can be combined in two ways: either a single mapping or a redundant mapping allowing high-precision phase recovery using a Shack–Hartmann-like algorithm. We demonstrate both methods in a nitrogen test case, which allows disentangling structural and dynamical effects. Two-dimensional phase cartography paves the way to high-resolution high-harmonic spectroscopy for applications such as quantum orbital tomography and attosecond charge migration in molecules.

中文翻译：

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高谐波光谱的二维相位制图

基于高次谐波产生的极非线性光谱学已成为研究气体和固体目标中阿秒动力学的有力方法。特别是，谐波发射的相位对原子和分子的结构以及动力学具有深刻的见解。但是，当前技术仅沿特定方向提供相位测量，因此提供了部分表征。在这里，我们报告了一种结合了光学和量子干涉仪的新方法，该方法沿二维在完全相同的实验条件下测量了来自对准分子的谐波发射的强度和相位。这种二维制图技术可在没有任意偏移且其符号没有不确定性的情况下测量相位。沿不同维度的测量可以通过两种方式组合：无论是单个映射还是冗余映射，都可以使用类似于Shack–Hartmann的算法进行高精度相位恢复。我们在氮气测试案例中演示了这两种方法，这可以使结构和动力学效果脱颖而出。二维相位制图为高分辨率高谐波光谱学的应用铺平了道路，例如量子轨道层析成像和分子中的阿秒电荷迁移。