Microwave optomechanical circuits have been demonstrated in the past years to be extremely powerfool tools for both, exploring fundamental physics of macroscopic mechanical oscillators as well as being promising candidates for novel on-chip quantum limited microwave devices. In most experiments so far, the mechanical oscillator is either used as a passive device element and its displacement is detected using the superconducting cavity or manipulated by intracavity fields. Here, we explore the possibility to directly and parametrically manipulate the mechanical nanobeam resonator of a cavity electromechanical system, which provides additional functionality to the toolbox of microwave optomechanical devices. In addition to using the cavity as an interferometer to detect parametrically modulated mechanical displacement and squeezed thermomechanical motion, we demonstrate that parametric modulation of the nanobeam resonance frequency can realize a phase-sensitive parametric amplifier for intracavity microwave photons. In contrast to many other microwave amplification schemes using electromechanical circuits, the presented technique allows for simultaneous cooling of the mechanical element, which potentially enables this type of optomechanical microwave amplifier to be quantum-limited. INTRODUCTIONSuperconducting microwave circuits have been demonstrated to be extremely powerful tools for the fields of quantum information processing 1-3 , circuit quantum electrodynamics 4-8 , astrophysical detector technologies 9 and microwave optomechanics 10-12 . In the latter, microwave fields in superconducting cavities are parametrically coupled to mechanical elements such as suspended capacitor drumheads or metallized nanobeams, enabling high-precision detection and manipulation of mechanical motion. Milestones achieved in the field include sideband-cooling of mechanical oscillators to the quantum ground state 11 , strong coupling between photons and phonons 13 , the generation of non-Gaussian states of motion [14][15][16] or the entanglement between two mechanial oscillators 17 .Recently, there are increasing efforts taken towards building passive and active quantum limited microwave elements for quantum technologies based on microwave optomechanical circuits, connecting the fields of microwave optomechanics, circuit quantum electrodynamics and quantum information science 18-20 . Among the most important developments into this direction are the demonstration of microwave amplification by blue sideband driving in simple optomechanical circuits 21 , and the realization of directional microwave amplifiers 22 as well as microwave circulators 23,24 in more complex multimode systems 25 .Recent theoretical work 26-28 on optomechanical systems with a parametrically driven mechanical oscillator proposed the use of mechanical parametric driving to enable parametric amplification with enhanced bandwidth and reduced added noise, compared to the case of a optomechanical amplifier using a blue-sideband drive 26 . Furthermore, the authors pre...
BackgroundIdiopathic pulmonary arterial hypertension (IPAH) is a rare, fatal disease of unknown pathogenesis. Evidence from our recent study suggests that IPAH pathogenesis is related to upregulation of the Wnt/planar cell polarity (Wnt/PCP) pathway. We used microscopic observation and immunohistochemical techniques to identify expression patterns of cascading proteins—namely Wnt-11, dishevelled-2 (Dvl-2), and dishevelled-associated activator of morphogenesis 1 (Daam-1)—in pulmonary arteries.MethodsWe analyzed sections of formalin-fixed and paraffin-embedded autopsied lung tissues obtained from 9 IPAH cases, 7 associated pulmonary arterial hypertension cases, and 16 age-matched controls without pulmonary arterial abnormalities. Results of microscopic observation were analyzed in relation to the cellular components and size of pulmonary arteries.ResultsVarying rates of positive reactivity to Dvl-2 and Daam-1 were confirmed in all cellular components of pulmonary arteries, namely, endothelial cells, myofibroblasts, and medial smooth muscle cells. In contrast, none of these components was reactive to Wnt-11. No specific expression patterns were observed for endothelial cells or myofibroblasts under any experimental conditions. However, marked expression of Dvl-2 and Daam-1 was confirmed in smooth muscle cells. In addition, Dvl-2 was depleted while Daam-1 expression was elevated in IPAH, in contrast with specimens from associated pulmonary arterial hypertension cases and controls.ConclusionsHigh Daam-1 expression may upregulate the Wnt/PCP pathway and cause IPAH.
We experimentally investigate dissipation in mechanical resonators made of a disordered superconducting thin film of Molybdenum-Rhenium(MoRe) alloy. By electrostatically driving the drum with a resonant AC voltage, we detect its motion using a superconducting microwave cavity. From the temperature dependence of mechanical resonance frequencies and quality factors, we find evidence for non-resonant, mechanically active two-level systems (TLSs) limiting its quality factor at low temperature. In addition, we observe a strong suppression of mechanical dissipation at large mechanical driving amplitudes, suggesting an unconventional saturation of the non-resonant TLSs. These new observations shed light on the mechanism of mechanical damping in superconducting drums and routes towards understanding dissipation in such mechanical systems
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