In this thesis, we characterize and test a new MiM cavity for use in the Bouwmeester Optomechanics group. The cavity seems stable over time, though alignment offers some issues. The tip/tilt...Show moreIn this thesis, we characterize and test a new MiM cavity for use in the Bouwmeester Optomechanics group. The cavity seems stable over time, though alignment offers some issues. The tip/tilt alignment of the membrane was achieved to within 700 arcs eventually however. We also explore the use of finesse measurements to determine the absorbance of our membranes. We conclude that optical ring down measurements are preferable in our system and suspect that the PSG4 membranes have higher absorbance as compared to later generations. We present a scheme to determine the thermal gradient of our membrane in-situ, without any modifications required to the principle of the system. We do find, however, that the measurement is very sensitive to drift of the laser detuning. Finally, we explore the observed short term drift in our mechanical mode frequencies. We suspect the thermal expansion of some part of the system of adding additional strain to the membranes, and in doing so raising their mode frequencies, though the exact pathway remains unclear.Show less
By temporally and spatially overlapping a fundamental femtosecond pulse (800 nm wavelength) and its second harmonic (400 nm wavelength) at a focal point in air, plasma is generated which is a good...Show moreBy temporally and spatially overlapping a fundamental femtosecond pulse (800 nm wavelength) and its second harmonic (400 nm wavelength) at a focal point in air, plasma is generated which is a good source of intense and ultrabroadband terahertz waves. We study the correlation between the spectral properties of the two-color laser-induced air plasma and the amplitude of the emitted terahertz electric field while varying the relative phase between the 800 nm and 400 nm beams. We find that the amplitude of the terahertz electric fi eld shows an oscillating behavior when changing the relative phase. In particular, for 0.67 fs time delay between the two beams, which corresponds to a phase shift of pi, terahertz waves with opposite polarities are obtained. However, the spectrum of the ultraviolet light emitted from the laser-induced air plasma does not show any noteworthy changes when varying the relative phase. Therefore, we conclude that there is no correlation between the amplitude of the emitted terahertz electric field and the spectrum of the two-color laser-induced air plasma.Show less
A cavity quantum electrodynamics system consisting of quantum dots in a micropillar cavity may form an essential building block for the creation of a quantum network. Current systems do not allow...Show moreA cavity quantum electrodynamics system consisting of quantum dots in a micropillar cavity may form an essential building block for the creation of a quantum network. Current systems do not allow for the scaling, in a simple manner, to a large network. Therefore, we introduce a scalable approach by coupling a micropillar cavity to single-mode fibers. The steps taken to achieve the fiber coupling are explained and the first tests for researching a fiber coupled cavity quantum electrodynamics system are shown. The first tests show that full input-output fiber based polarization control of a micropillar cavity at 3.5 K is possible which is important for a photon polarization based quantum network. Several experimental challenges are shown and discussed. Despite the experimental challenges, the first tests may pave the way for a more scalable approach for building a large-scale quantum network.Show less
Motional control of mechanical resonators is crucial for their applications. In particular, cooling the mechanical mode to overcome the thermal noise has been greatly explored, and has recently...Show moreMotional control of mechanical resonators is crucial for their applications. In particular, cooling the mechanical mode to overcome the thermal noise has been greatly explored, and has recently been pushed into the quantum regime. In this thesis, we study an almost-forgotten cooling technique: resistive cooling with an artificial cold resistor (ACR) which is physically at room temperature. We perform a proof-of-principle demonstration to cool a mechanical mode of a quartz crystal with a “cold” resistor. The “cold” resistor is realised either by a normal resistor cooled by liquid nitrogen or by an ACR made of a special circuitry. We show that the ACR can cool the mode in the same way as a real cold resistor, and the cooling mechanism can be qualitatively understood in the basic thermodynamic picture. We also discuss the feasibility of applying such resistive cooling to an optomechanical system, with a nested trampoline resonator.Show less
