47 research outputs found
Strain-tuning of quantum dot optical transitions via laser-induced surface defects
We discuss the fine-tuning of the optical properties of self-assembled
quantum dots by the strain perturbation introduced by laser-induced surface
defects. We show experimentally that the quantum dot transition red-shifts,
independently of the actual position of the defect, and that such frequency
shift is about a factor five larger than the corresponding shift of a
micropillar cavity mode resonance. We present a simple model that accounts for
these experimental findings.Comment: 9 pages, 6 figures. To appear in Phys. Rev.
Quantum dot nonlinearity through cavity-enhanced feedback with a charge memory
In an oxide apertured quantum dot (QD) micropillar cavity-QED system, we
found strong QD hysteresis effects and lineshape modifications even at very low
intensities corresponding to less than 0.001 intracavity photons. We attribute
this to the excitation of charges by the intracavity field; charges that get
trapped at the oxide aperture, where they screen the internal electric field
and blueshift the QD transition. This in turn strongly modulates light
absorption by cavity QED effects, eventually leading to the observed hysteresis
and lineshape modifications. The cavity also enables us to observe the QD
dynamics in real time, and all experimental data agrees well with a power-law
charging model. This effect can serve as a novel tuning mechanism for quantum
dots.Comment: 7 pages, 6 figure
Tuning micropillar cavity birefringence by laser induced surface defects
We demonstrate a technique to tune the optical properties of micropillar
cavities by creating small defects on the sample surface near the cavity region
with an intense focused laser beam. Such defects modify strain in the
structure, changing the birefringence in a controllable way. We apply the
technique to make the fundamental cavity mode polarization-degenerate and to
fine tune the overall mode frequencies, as needed for applications in quantum
information science.Comment: RevTex, 7 pages, 4 figures (accepted for publication in Applied
Physics Letters
CNOT and Bell-state analysis in the weak-coupling cavity QED regime
We propose an interface between the spin of a photon and the spin of an
electron confined in a quantum dot embedded in a microcavity operating in the
weak coupling regime. This interface, based on spin selective photon reflection
from the cavity, can be used to construct a CNOT gate, a multi-photon entangler
and a photonic Bell-state analyzer. Finally, we analyze experimental
feasibility, concluding that the schemes can be implemented with current
technology.Comment: 4 pages, 2 figure
H1 photonic crystal cavitites for hybrid quantum information protocols
Hybrid quantum information protocols are based on local qubits, such as
trapped atoms, NV centers, and quantum dots, coupled to photons. The coupling
is achieved through optical cavities. Here we demonstrate far-field optimized
H1 photonic crystal membrane cavities combined with an additional back
reflection mirror below the membrane that meet the optical requirements for
implementing hybrid quantum information protocols. Using numerical optimization
we find that 80% of the light can be radiated within an objective numerical
aperture of 0.8, and the coupling to a single-mode fiber can be as high as 92%.
We experimentally prove the unique external mode matching properties by
resonant reflection spectroscopy with a cavity mode visibility above 50%.Comment: 14 pages, 11 figure