20 research outputs found
Stoppage of Light Made Flexible by an Additional Control Field
We show how the application of a coupling field connecting the two lower
metastable states of a Lambda system facilitates stoppage of light in a coheren
tly driven Doppler broadened atomic medium via electromagnetic induced
transparencyComment: 11 pages, 3 figures, typed in Latex, Accepted in JM
Causality in Propagation of a Pulse in a Nonlinear Dispersive Medium
We investigate the causal propagation of the pulse through dispersive media
by very precise numerical solution of the coupled Maxwell-Bloch equations
without any approximations about the strength of the input field. We study full
nonlinear behavior of the pulse propagation through solid state media like ruby
and alexandrite. We have demonstrated that the information carried by the
discontinuity, {\it i.e}, front of the pulse, moves inside the media with
velocity even though the peak of the pulse can travel either with
sub-luminal or with super-luminal velocity. We extend the argument of
Levi-Civita to prove that the discontinuity would travel with velocity even
in a nonlinear medium.Comment: 4 pages, 4 figures, 2 table
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
Coherent population transfer with polariton states in circuit QED
This article proposes a new method to increase the efficiency of stimulated
Raman adiabatic passage (STIRAP) in superconducting circuits using a shortcut
to the adiabaticity (STA) method. The STA speeds up the adiabatic process
before decoherence has a significant effect, thus leading to increased
efficiency. This method achieves fast, high-fidelity coherent population
transfer, known as super-adiabatic STIRAP (saSTIRAP), in a dressed
state-engineered system with polariton states in circuit QED
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