Wallace, W CPullen, M GLaban, D EPalmer, A JHanne, G FGrum-Grzhimailo , A NAbeln, BBartschat, Klaus RWeflen, DIvanov, IgorKheifets, AnatoliQuiney, Harry MorrisLitvinyuk, I VSang, Robert TKielpinski, D2015-12-081742-6596http://hdl.handle.net/1885/30152The interaction of intense few-cycle light pulses and matter has given rise to a number of high-field physical processes that are of great interest. The high non-linearity of such interactions necessitates complex numerical simulations in order to retrieve useful physical measurements from the experimental data. Here we demonstrate quantitative agreement at the 10% level between experimentally obtained integrated photoelectron spectra and numerical simulations for above-threshold ionization in the intense few-cycle regime. The use of atomic hydrogen provides a key experimental innovation as it is the only electronic system for which ab initio simulations in this regime are available.Author/s retain copyrightKeywords: Ab initio simulations; Above-threshold ionization; Atomic hydrogen; Electronic systems; Few-cycle; Few-cycle laser pulse; High-field; Light pulse; Photoelectron spectrum; Physical measurement; Physical process; Quantitative agreement; Computer simulation;201210.1088/1742-6596/388/3/0320552016-02-24