Resonant strings are a promising concept for ultra sensitive temperature detection. We present an analytical model for the sensitivity with which we optimize the temperature response of resonant strings by varying geometry and material. The temperature sensitivity of silicon nitride and aluminum microstrings was measured. The relative change in resonant frequency per temperature change of −1.74±0.04%/°C of the aluminum strings is more than one order of magnitude higher than of the silicon nitride strings and of comparable state-of-the-art AuPd strings.

Today's supercapacitor energy storages are typically discrete devices aimed for printed boards and power applications. The development of autonomous sensor networks and wearable electronics and the miniaturisation of mobile devices would benefit substantially from solutions in which the energy storage is integrated with the active device. Nanostructures based on porous silicon (PS) provide a route towards integration due to the very high inherent surface area to volume ratio and compatibility with microelectronics fabrication processes. Unfortunately, pristine PS has limited wettability and poor chemical stability in electrolytes and the high resistance of the PS matrix severely limits the power efficiency. In this work, we demonstrate that excellent wettability and electro-chemical properties in aqueous and organic electrolytes can be obtained by coating the PS matrix with an ultra-thin layer of titanium nitride by atomic layer deposition. Our approach leads to very high specific capacitance (15 Fcm -3 ), energy density (1.3 mWhcm -3 ) , p o w e r d e n s i t y ( u p t o 2 1 4 W c m -3 ) and excellent stability (more than 13,000 cycles). Furthermore, we show that the PS-TiN nanomaterial can be integrated inside a silicon chip monolithically by combining MEMS and nanofabrication techniques. This leads to realisation of in-chip supercapacitor, i.e., it opens a new way to exploit the otherwise inactive volume of a silicon chip to store energy.

We demonstrate that a suspended metal wire array can be used to produce high-pressure sound waves over a wide spectrum using the thermoacoustic effect. We fabricated air-bridge arrays containing up to 2 ϫ 10 5 wires covering an area of a few square centimeters. The supporting silicon wafer was isotropically plasma etched to release the wires thereby avoiding heat contact with the substrate. Sound pressure levels reaching 110 dB at a distance of 8 cm were demonstrated near 40 kHz in free field. The devices are also able to reproduce music and speech. They have potential for applications especially in the ultrasound range.

The shift of energy levels owing to broadband electromagnetic vacuum fluctuations-the Lamb shift-has been pivotal in the development of quantum electrodynamics and in understanding atomic spectra 1-6 . Currently, small energy shifts in engineered quantum systems are of paramount importance owing to the extreme precision requirements in applications such as quantum computing 7,8 . However, without a tunable environment it is challenging to resolve the Lamb shift in its original broadband case. Consequently, the observations in other than atomic systems [1][2][3][4][5]9 are limited to environments comprised of narrowband modes 10-12 . Here, we observe a broadband Lamb shift in high-quality superconducting resonators, a scenario also accessing any static shift inaccessible in Lamb's experiment 1,2 . We measure a continuous change of several megahertz in the fundamental resonator frequency by externally tuning the coupling strength of the engineered broadband environment which is based on hybrid normal-metal-superconductor tunnel junctions [13][14][15] . Our results may lead to improved control of dissipation in high-quality engineered quantum systems and open new possibilities for studying synthetic open quantum matter 16-18 using this hybrid experimental platform.Physical quantum systems are always open. Thus, exchange of energy and information with an environment eventually leads to relaxation and degradation of quantum coherence. Interestingly, the environment can be in a vacuum state and yet cause significant perturbation to the original quantum system. The quantum vacuum can be modelled as broadband fluctuations which may absorb energy from the coupled quantum systems. These fluctuations also lead to an energy level renormalizationthe Lamb shift-of the system, such as that observed in atomic systems [1][2][3][4][5]9 . Despite of its fundamental nature, the Lamb shift arising from broadband fluctuations is often overlooked outside the field of atomic physics as a small constant shift that is challenging to distinguish 20 . Due to the emergence of modern engineered quantum systems, in which the desired precision of the energy levels is comparable to the Lamb shift, it has, however, become important to predict accurately the perturbation as a function of external control parameters. Neglecting energy shifts can potentially take the engineered quantum systems outside the region of efficient operation 21,22 and may even lead to undesired level crossings between subsystems. These issues are pronounced in applications requiring strong dissipation. Examples include reservoir engineering for autonomous quantum error correction 23,24 , or rapid on-demand entropy and heat evacuation 14,15,25,26 . Furthermore, the role of dissipation in phase transitions of open many-body quantum systems has attracted great interest through the recent progress in studying synthetic quantum matter 16,17 .In our experimental setup, the system exhibiting the Lamb shift is a superconducting coplanar waveguide resonator with the resonance frequ...

We describe the construction and performance of a passive, real-time terahertz camera based on a modular, 64-element linear array of cryogenic hotspot microbolometers. A reflective conical scanner sweeps out a 2 m x 4 m (vertical x horizontal) field of view (FOV) at a standoff range of 8 m. The focal plane array is cooled to 4 K in a closed cycle refrigerator, and the signals are detected on free-standing bridges of superconducting Nb or NbN at the feeds of broadband planar spiral antennas. The NETD of the focal-plane array, referred to the target plane and to a frame rate of 5 s(-1), is 1.25 K near the center of the array and 2 K overall.