Quantum battles in attoscience: tunnelling

Abstract

What is the nature of tunnelling? This yet unanswered question is as pertinent today as it was at the dawn of quantum mechanics. This article presents a cross section of current perspectives on the interpretation, computational modelling, and numerical investigation of tunnelling processes in attosecond physics as debated in the Quantum Battles in Attoscience virtual workshop 2020. Graphic abstract

Время Квантового Туннелирования Умеренно Сингулярного Потенциала: Метод Регуляризации

“…Другим важным аспектом рассматриваемой проблемы, мало изученным особенно экспериментально, является время квантового туннелирования [13,[16][17][18][19]. Это связано не только с тем, что время в формализме квантовой механики не является динамической переменной, но и с существованием парадокса МакКолла-Хартмана [20,21].…”

Joint probability calculation of the lateral velocity distribution in strong field ionization process

“…The most essential features of these processes can often be understood with the help of the well-known simple man model (SMM) 6,[10][11][12][13] , which represents electron's motion after the ionization event occurs as entirely classical. This fact underlies a variety of highly efficient semi-classical approaches [12][13][14][15][16][17][18][19] , in which the electron ionization event is treated quantum-mechanically, with electron's ionization occurring near the local peaks of the electric field, and the subsequent electron motion treated classically or semi-classically. These approaches include the well-known TIPIS model 12,16,20 , the quantum trajectory Monte Carlo model (QTMC) 19 , semi-classical two-step model 21 or Coulomb quantum orbit strong-field approximation (CQSFA) 22,23 .…”

“…We do not specify the constant A in this expression as we will be interested below in the distribution shape which is described by the exponential function. Expression (15) gives us the final velocity distribution at the detector when the laser pulse is gone, but it can also be used as a plausible expression for the lateral velocity distribution within interval of the pulse duration, as is done e.g., in the semi-classical simulations 12,16,20,21 . The rational behind that is that a linearly polarized electric field does not affect the distribution in the lateral direction during the electron's motion subsequent to the ionization event.…”

“…The rational behind that is that a linearly polarized electric field does not affect the distribution in the lateral direction during the electron's motion subsequent to the ionization event. The width of the lateral velocity SFA distribution (15) can, therefore, be used as a guide in choosing the value for the parameter d we used to foliate the velocity space. For the field strengths of the order of E 0 ≈ 0.07 we are interested in, the full width at half maximum (FWHM) of the distribution ( 15) is approximately 0.45 a.u., so our choice of d = 0.1 a.u.…”

Zeptosecond Angular Streak Camera

“…The production of ultrashort intense extreme ultraviolet (XUV) laser pulses [1,2] from high harmonic generation (HHG) [3][4][5] along with the development of spectroscopic techniques, such as the linear attosecond streak camera (LSC) [2,6], the reconstruction of attosecond beating by interference of two-photon transitions (RABBITT) [1], and the attoclock technique [7], enables the temporal resolution in the few attosecond (1 as = 10 −18 s) domain and, thus, on the natural time scale of electron dynamics. Recent timeresolved observations of the atomic photoionization [8][9][10], tunneling ionization [11][12][13][14][15][16][17][18][19][20][21], correlation-mediated photoionization time delay [22,23], valence shell electron dynamics [24,25], and the laser-driven electron dynamics in a molecule [26][27][28][29] are striking examples for the capabilities of these techniques, leading to the rapid development of the attosecond metrology and chronoscopy [30].…”