Keldysh time bounds of laser-driven ionization dynamics

Abstract

We revisit the energy–time uncertainty underpinning of the pointwise bounds of laser-driven ionization dynamics. When resolved within the driver pulse and its field cycle, these bounds are shown to manifest the key signature tendencies of photoionization current dynamics—a smooth growth within the pulse in the regime of multiphoton ionization and an abrupt, almost stepwise photocurrent buildup within a fraction of the field cycle in the limit of tunneling ionization. In both regimes, the Keldysh time, defined as the ratio of the Keldysh parameter to the driver frequency, serves as a benchmark for the minimum time of photoionization, setting an upper bound for the photoelectron current buildup rate.

Thermal and Quantum Barrier Passage as Potential-Driven Markovian Dynamics

“…As shown in the earlier work, − τ K can be related to the imaginary time, found by minimizing the action of an electron traversing the potential barrier. This approach turns out to be rather productive as it helps define important parameters of laser-induced ionization and allows the Keldysh photoionization theory to be extended to ultrashort laser pulses. − Within the framework presented in this paper, the Keldysh tunneling time can be understood, very much in the spirit of the original Keldysh argument, by resorting to classical real-time dynamics driven by an inverted potential, − V S , in which the area under the barrier of V S is classically allowed.…”

Information geometry, Pythagorean-theorem extension, and Euclidean distance behind optical sensing via spectral analysis

“…Recognizing a geometric structure behind the key information-theory concepts [2][3][4][5][6] has been pivotal to appreciating the statistical underpinning of a vast class of uncertainty relations in evolution biology, quantum physics, statistical mechanics, and thermodynamics as fundamental bounds set out by the intrinsic properties of statistical divergences, understood in terms of distances and metrics in the space of statistics. Such metrics, as recent studies show, offer important insights into fundamental speed limits in quantum information processing [5][6][7], as well as ultrafast laser-driven quantum dynamics in physical, chemical, and biological systems [8][9][10].…”