329 research outputs found
Strong non-linearity-induced correlations for counter-propagating photons scattering on a two-level emitter
We analytically treat the scattering of two counter-propagating photons on a
two-level emitter embedded in an optical waveguide. We find that the
non-linearity of the emitter can give rise to significant pulse-dependent
directional correlations in the scattered photonic state, which could be
quantified via a reduction in coincident clicks in a Hong-Ou-Mandel measurement
setup, analogous to a linear beam splitter. Changes to the spectra and phase of
the scattered photons, however, would lead to reduced interference with other
photons when implemented in a larger optical circuit. We introduce suitable
fidelity measures which account for these changes, and find that high values
can still be achieved even when accounting for all properties of the scattered
photonic state.Comment: 10 pages, 7 figure
Saturation properties of four-wave mixing between short optical pulses in semiconductor optical amplifiers
Measuring the effective phonon density of states of a quantum dot
We employ detuning-dependent decay-rate measurements of a quantum dot in a
photonic-crystal cavity to study the influence of phonon dephasing in a
solid-state quantum-electrodynamics experiment. The experimental data agree
with a microscopic non-Markovian model accounting for dephasing from
longitudinal acoustic phonons, and identifies the reason for the hitherto
unexplained difference between non-resonant cavity feeding in different
nanocavities. From the comparison between experiment and theory we extract the
effective phonon density of states experienced by the quantum dot. This
quantity determines all phonon dephasing properties of the system and is found
to be described well by a theory of bulk phonons.Comment: 5 pages, 3 figures, submitte
Controlling the speed of light in semiconductor waveguides: Physics and applications:[invited]
Driving-induced population trapping and linewidth narrowing via the quantum Zeno effect
We investigate the suppression of spontaneous emission from a driven
three-level system embedded in an optical cavity via a manifestation of the
quantum Zeno effect. Strong resonant coupling of the lower two levels to an
external optical field results in a decrease of the exponential decay rate of
the third upper level. We show that this effect has observable consequences in
the form of emission spectra with subnatural linewidths, which should be
measurable using, for example, quantum dot--cavity systems in currently
obtainable parameter regimes. These results constitute a novel method to
control an inherently irreversible and dissipative process, and may be useful
in applications requiring the control of single photon arrival times and
wavepacket extent
Limitations of two-level emitters as nonlinearities in two-photon controlled-phase gates
We investigate the origin of imperfections in the fidelity of a two-photon
controlled-phase gate based on two-level-emitter non-linearities. We focus on a
passive system that operates without external modulations to enhance its
performance. We demonstrate that the fidelity of the gate is limited by
opposing requirements on the input pulse width for one- and two-photon
scattering events. For one-photon scattering, the spectral pulse width must be
narrow compared to the emitter linewidth, while two-photon scattering processes
require the pulse width and emitter linewidth to be comparable. We find that
these opposing requirements limit the maximum fidelity of the two-photon
controlled-phase gate for Gaussian photon pulses to 84%.Comment: 7 pages, 6 figure
High-Q AlAs/GaAs adiabatic micropillar cavities with submicron diameters for cQED experiments
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