ABSTRACT
Process force determination in machine tools is an important topic for both optimization of manufacturing processes as well as predictive maintenance purposes. This work aims at providing a short overview of existing methods, motivating the integration of sensors into a linear guide, and then showing the results of an implemented new method for capturing the load on a rolling element linear guide by measuring the stresses resulting from the rolling element contact at the side of the runner block. The implementation of the approach is based on the piezoresistive diamond like carbon (DLC) coating DiaForce® provided by the Fraunhofer Institute for Surface Engineering and Thin Films (IST), Braunschweig, Germany. Good agreement of measurements with analytical and finite element method simulation results promises a stable modeling and load estimation process. Nevertheless, non-idealities due to high temperature dependency and cross-sensitivity to non rolling element contact related stresses could be shown, but also an efficient approach to diminish these effects is included.
ABSTRACT
In this letter, we report on quantum light emission from bulk AlInAs grown on InP(111) substrates. We observe indium rich clusters in the bulk Al0.48In0.52As (AlInAs), resulting in quantum dot-like energetic traps for charge carriers, which are confirmed via cross-sectional scanning tunnelling microscopy (XSTM) measurements and 6-band k·p simulations. We observe quantum dot (QD)-like emission signals, which appear as sharp lines in our photoluminescence spectra at near infrared wavelengths around 860 nm, and with linewidths as narrow as 50 µeV. We demonstrate the capability of this new material system to act as an emitter of pure single photons as we extract g(2)-values as low as gcw(2)(0)=0.05-0.05+0.17 for continuous wave (cw) excitation and gpulsed, corr.(2)=0.24±0.02 for pulsed excitation.
ABSTRACT
The implementation and engineering of bright and coherent solid state quantum light sources is key for the realization of both on chip and remote quantum networks. Despite tremendous efforts for more than 15 years, the combination of these two key prerequisites in a single, potentially scalable device is a major challenge. Here, we report on the observation of bright single photon emission generated via pulsed, resonance fluorescence conditions from a single quantum dot (QD) deterministically centered in a micropillar cavity device via cryogenic optical lithography. The brightness of the QD fluorescence is greatly enhanced on resonance with the fundamental mode of the pillar, leading to an overall device efficiency of η = (74 ± 4) % for a single photon emission as pure as g(2)(0) = 0.0092 ± 0.0004. The combination of large Purcell enhancement and resonant pumping conditions allows us to observe a two-photon wave packet overlap up to ν = (88 ± 3) %.
ABSTRACT
We report on the observation of bright emission of single photons under pulsed resonance fluorescence conditions from a single quantum dot (QD) in a micropillar cavity. The brightness of the QD fluorescence is greatly enhanced via the coupling to the fundamental mode of a micropillar, allowing us to determine a single photon extraction efficiency of (20.7 ± 0.8) % per linear polarization basis. This yields an overall extraction efficiency of (41.4 ± 1.5) % in our device. We observe the first Rabi-oscillation in a weakly coupled quantum dot-micropillar system under coherent pulsed optical excitation, which enables us to deterministically populate the excited QD state. In this configuration, we probe the single photon statistics of the device yielding g(2)(0) = 0.072 ± 0.011 at a QD-cavity detuning of 75 µeV.
