Quantum-path interferometry for high-harmonic generation

In this paper, the author proposed a general technique to decompose an observed field into individual quantum-path contributions, so as to extend the time range of attosecond dynamics experiments and enable observation of weaker contributions such as multiple return trajectories and recently suggested continuum-continuum interference. The authors perform quantum-path interferometry (QPI) by perturbing the phase of each quantum path using one or more control fields. Because each path responds differently to the control field, each can be distinguished. The authors develop the theory of QPI and provide numerical examples illustrating the retrieval the amplitude and relative phases of an arbitrary number of contributions, including those from long, short and multiple-return trajectories.