3 research outputs found
Rapid-adiabatic-passage-based super-resolution microscopy in semiconductor quantum dot system
We theoretically investigate rapid adiabatic passage(RAP)-based
super-resolution imaging in a two-level quantum dot system interacting with two
structured beams. To understand the physical mechanism behind the formation of
super-resolution for the experiment of Kaldewey {\it et. al.,}[Nature Photonics
10.1038/s41566-017-0079-y (2018)], we first use Liouville's density matrix
where photon-mediated radiative and non-radiative decays are incorporated. A
suitably chosen spatiotemporal envelope of the structured beams enables the
formation of a super-resolution image. We also find that the feature size of
the image depends on the intensity of the Laguerre Gaussian beam(LG). However,
the created image resolution undergoes distortion due to the existence of a
low-intensity circular ring. The unwanted circular ring arises from the
dominance of the LG beam tail over the super-Gaussian(SG) beam tail, initiating
the residual population transfer from the ground state to the excited state.
This limitation can be overcome by using the Bessel-modulated truncated
structured LG and SG beams. We next study the dynamics of the semiconductor
quantum dot system at finite temperatures wherein the phonon interaction
becomes imperative. We employ the polaron-transformed master equation to
explore the system at higher temperatures. Our numerical results confirm that
the sharpness of the image remains intact at low temperatures with weak phonon
coupling. Hence, the proposed scheme may open up applications in nano-scale
imaging with quantum dots.Comment: 14 pages, 12 figure
Self-induced Transparency in a Semiconductor Quantum Dot medium at ultra-cold temperatures
We investigate the feasibility of minimum absorption and minimum broadening
of pulse propagation in an inhomogeneously broadened semiconductor quantum dot
medium. The phonon interaction is inevitable in studying any semiconductor
quantum dot system. We have used the polaron transformation technique to deal
with quantum dot phonon interaction in solving system dynamics. We demonstrate
that a short pulse can propagate inside the medium with minimal absorption and
broadening in pulse shape. The stable pulse area becomes slightly higher than
the prediction of the pulse area theorem and is also dependent on the
environment temperature. The change in the final pulse shape is explained very
well by numerically solving the propagation equation supported by the
susceptibility of the medium. Our system also exhibits the pulse breakup
phenomena for higher input pulse areas. Therefore, the considered scheme can
have important applications in quantum communication, quantum information, and
mode-locking with the advantage of scalability and controllability.Comment: 11 pages, 11 figure
Nondegenerate two-photon lasing in a single quantum dot
We propose two-mode two-photon microlaser using a single semiconductor
quantum dot grown inside a two-mode microcavity. We explore both incoherent and
coherent pumping at low temperatures to achieve suitable conditions for
two-mode two-photon lasing. The two-mode two-photon stimulated emission is
strongly suppressed but the single-photon stimulated emission is enhanced by
exciton-phonon interactions. In coherently pumped quantum dot one can achieve
large two-mode two-photon lasing where single-photon lasing is almost absent.
We also discuss generation of steady state two-mode entangled state using
two-photon resonant pumping.Comment: 12 pages, 13 figure