Photons are the elementary quantum excitations of the electromagnetic field. Quantization is usually constructed on the basis of an expansion in eigenmodes, in the form of plane waves. Since they form a basis, other electromagnetic configurations can b…
We theoretically and experimentally investigate the Doppler-broadened absorption spectrum of the D 2
-line (5 2 S 1/2 → 5 2 P 3/2 ) in thermal (room-temperature) Rb vapour over a wide range of probe
intensity, probe diameter, and vapour cell temperature to understand the effect of hyperfine pumping
and transit-relaxation on the absorption lineshape. We present a relatively simple but comprehensive
five-level rate equation model which incorporates optical pumping of the atomic population into the
other ‘dark’ ground hyperfine level (leading to absorption saturation), including contributions of
the three closely spaced (within one Doppler linewidth) hyperfine levels in the excited state 5 2 P
3/2 (allowed by the dipole transition selection rules). D 2 -line transmission spectra predicted by
our model show excellent agreement (rms error ##IMG##
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Results of experimental and theoretical investigations into the electron-impact excitation of the
resonance ##IMG##
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Satellites i.e. two-hole-one-particle states appear due to many-electron correlations in
photoelectron spectra in addition to main lines corresponding to one-hole states. The correct
assignment of these states is important for understanding the photo…
The temporal and spectral consequences of an intermediate resonance en route to photoionization are
investigated theoretically in two ways: by solving few-level model equations and by ab initio
numerical solution of the time-dependent Schrödinger equ…
We present the angular profiles of the triple differential cross-section (TDCS) for the (e, 2e)
process on the noble gas atoms, namely He (1s), Ne (2s and 2p), and Ar (3p), for the plane wave and
the twisted electron impact. We develop the theoretica…
In this work, the Imbert–Fedorov (IF) shift is systematically investigated when a light beam is
incident on black phosphorus. Using the angular spectrum theory, we obtain the analytical
expressions of IF shifts for a p -polarized and s -polarized bea…
A simple analytical expression for the potential energy curve for the ground state X 1 Σ + of the
hydrogen fluoride molecule HF obtained in the framework of the Born–Oppenheimer approximation is
proposed. This analytical expression for the potential …
Precise control and knowledge over atomic dynamics is central to the advancement of quantum
technology. The different experimental conditions namely, atoms in a vacuum, antirelaxation coated
and buffer gas filled atomic cells provide complementary pl…
The dynamical behaviors of a quasi-2D Bose–Einstein condensate (BEC) with three-body interactions
through a moving obstacle potential are studied numerically. Various vortex structures are
discovered under different strength of three-body interaction…