254 research outputs found
Climbing the Jaynes-Cummings ladder by photon counting
We present a new method to observe direct experimental evidence of
Jaynes--Cummings nonlinearities in a strongly dissipative cavity quantum
electrodynamics system, where large losses compete with the strong light-matter
interaction. This is a highly topical problem, particularly for quantum dots in
microcavities where transitions from higher rungs of the Jaynes--Cummings
ladder remain to be evidenced explicitly. We compare coherent and incoherent
excitations of the system and find that resonant excitation of the detuned
emitter make it possible to unambiguously evidence few photon quantum
nonlinearities in currently available experimental systems.Comment: 4 pages, 4 figures (color online). Updated bb
Dynamic acousto-mechanical control of a strongly coupled photonic molecule
Two-dimensional photonic crystal membranes provide a versatile planar
architecture for integrated photonics to control the propagation of light on a
chip employing high quality optical cavities, waveguides, beamsplitters or
dispersive elements. When combined with highly non-linear quantum emitters,
quantum photonic networks operating at the single photon level come within
reach. Towards large-scale quantum photonic networks, selective dynamic control
of individual components and deterministic interactions between different
constituents are of paramount importance. This indeed calls for switching
speeds ultimately on the system's native timescales. For example, manipulation
via electric fields or all-optical means have been employed for switching in
nanophotonic circuits and cavity quantum electrodynamics studies. Here, we
demonstrate dynamic control of the coherent interaction between two coupled
photonic crystal nanocavities forming a photonic molecule. By using an
electrically generated radio frequency surface acoustic wave we achieve
optomechanical tuning, demonstrate operating speeds more than three orders of
magnitude faster than resonant mechanical approaches. Moreover, the tuning
range is large enough to compensate for the inherent fabrication-related cavity
mode detuning. Our findings open a route towards nanomechanically gated
protocols, which hitherto have inhibited the realization in all-optical
schemes.Comment: submitted manuscrip
Thickness Insensitive Nanocavities for 2D Heterostructures using Photonic Molecules
Two-dimensional (2D) heterostructures integrated into nanophotonic cavities
have emerged as a promising approach towards novel photonic and opto-electronic
devices. However, the thickness of the 2D heterostructure has a strong
influence on the resonance frequency of the nanocavity. For a single cavity,
the resonance frequency shifts approximately linearly with the thickness. Here,
we propose to use the inherent non-linearity of the mode coupling to render the
cavity mode insensitive to the thickness of the 2D heterostructure. Based on
the couple mode theory, we reveal that this goal can be achieved using either a
homoatomic molecule with a filtered coupling or heteroatomic molecules. We
perform numerical simulations to further demonstrate the robustness of the
eigenfrequency in the proposed photonic molecules. Our results render
nanophotonic structures insensitive to the thickness of 2D materials, thus
owing appealing potential in energy- or detuning-sensitive applications such as
cavity quantum electrodynamics
Recent advances in exciton based quantum information processing in quantum dot nanostructures
Recent experimental developments in the field of semiconductor quantum dot
spectroscopy will be discussed. First we report about single quantum dot
exciton two-level systems and their coherent properties in terms of single
qubit manipulations. In the second part we report on coherent quantum coupling
in a prototype "two-qubit" system consisting of a vertically stacked pair of
quantum dots. The interaction can be tuned in such quantum dot molecule devices
using an applied voltage as external parameter.Comment: 37 pages, 15 figures, submitted to New Journal of Physics, focus
issue on Solid State Quantum Information, added reference
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