69 research outputs found
Two-electron ionization in strong laser fields below intensity threshold: signatures of attosecond timing in correlated spectra
We develop an analytical model of correlated two-electron ionization in
strong infrared laser fields. The model includes all relevant interactions
between the electrons, the laser field, and the ionic core nonperturbatively.
We focus on the deeply quantum regime, where the energy of the active electron
driven by the laser field is insufficient to collisionally ionize the parent
ion, and the assistance of the laser field is required to create a doubly
charged ion. In this regime, the electron-electron and the electron-ion
interactions leave distinct footprints in the correlated two-electron spectra,
recording the mutual dynamics of the escaping electrons.Comment: 25 pages and 4 figure
Towards Single Atom Computing via High Harmonic Generation
The development of alternative platforms for computing has been a
longstanding goal for physics, and represents a particularly pressing concern
as conventional transistors approach the limit of miniaturization. A potential
alternatice paradigm is that of reservoir computing, which leverages unknown,
but highly non-linear transformations of input-data to perform computations.
This has the advantage that many physical systems exhibit precisely the type of
non-linear input-output relationships necessary for them to function as
reservoirs. Consequently, the quantum effects which obstruct the further
development of silicon electronics become an advantage for a reservoir
computer. Here we demonstrate that even the most basic constituents of matter -
atoms - can act as a reservoir for optical computers, thanks to the phenomenon
of High Harmonic Generation (HHG). A prototype single-atom computer for
classification problems is proposed, where parameters of the classification
model are mapped to optical elements. We numerically demonstrate that this
`all-optical' computer can successfully classify data with an accuracy that is
strongly dependent on dynamical non-linearities. This may pave the way for the
development of petahertz information processing platforms.Comment: 5 pages, 6 figure
Free to Harmonic Unitary Transformations in Quantum and Koopman Dynamics
It has long been known that there exists a coordinate transformation which
exactly maps the quantum free particle to the quantum harmonic oscillator. Here
we extend this result by reformulating it as a unitary operation followed by a
time coordinate transformation. We demonstrate that an equivalent
transformation can be performed for classical systems in the context of Koopman
von-Neumann (KvN) dynamics. We further extend this mapping to dissipative
evolutions in both the quantum and classical cases, and show that this mapping
imparts an identical time-dependent scaling on the dissipation parameters for
both types of dynamics. The derived classical procedure presents a number of
opportunities to import squeezing dependent quantum procedures (such as
Hamiltonian amplification) into the classical regime.Comment: 5 pages, no figure
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