Quantum interference and imaging using intense laser fields

The interference of matter waves is one of the intriguing features of quantum mechanics that has impressed researchers and laymen since it was first suggested almost a century ago. Nowadays, attosecond science tools allow us to utilize it in order to extract valuable information from electron wave packets. Intense laser fields are routinely employed to create electron wave packets and control their motion with attosecond and ångström precision. In this perspective article, which is based on our debate at the Quantum Battles in Attoscience virtual workshop 2020, we discuss some of the peculiarities of intense light-matter interaction. We review some of the most important techniques used in attosecond imaging, namely photoelectron holography and laser-induced electron diffraction. We attempt to ask and answer a few questions that do not get asked very often. For example, if we are interested in position space information, why are measurements carried out in momentum space? How to accurately retrieve photoelectron spectra from the numerical solution of the time-dependent Schrödinger equation? And, what causes the different coherence properties of high-harmonic generation and above-threshold ionization? GraphicAbstract

Laser-Induced Control of the Optical Response of Aluminum Phthalocyanine Chloride Complexes Dissolved in Ethanol

We show that absorption spectra of aluminum chloride phthalocyanine (AlClPc) in the liquid phase can be dynamically modified through the time-resolved interaction with a second laser pulse during a time window on the order of 100 fs. The observed effects can be explained by laser-induced coherent coupling dynamics between the ground state and a bath of excited states as reproduced by a few-level toy model. The presented results help to understand how intense laser fields interact with complex molecules in solution, but in their laser-controlled response still much alike isolated atoms in the gas phase. This understanding can, in the future, be used to modify and control the dynamics in complex systems.