Related papers: 1/ f noise and two-level systems in MBE-grown Al t…
$1/f$ noise caused by microscopic Two-Level Systems (TLS) is known to be very detrimental to the performance of superconducting quantum devices but the nature of these TLS is still poorly understood. Recent experiments with superconducting…
The accurate analytical solution for the low temperature $1/f$ noise in a microwave dielectric constant of amorphous films containing tunneling two-level systems (TLSs) is derived within the standard tunneling model including the weak…
Here we find the increase in 1/f noise of superconducting resonators at low temperatures to be completely incompatible with the standard tunneling model (STM) of Two Level Systems (TLS), which has been used to describe low-frequency noise…
Disordered thin films are a common choice of material for superconducting, high impedance circuits used in quantum information or particle detector physics. A wide selection of materials with different levels of granularity are available,…
Superconducting properties of thin films can be vastly different from those of bulk materials. Seminal work has shown the critical temperature Tc of elemental superconductors decreases with decreasing film thickness when the normal-state…
Two-level system (TLS) defects in dielectrics are known to limit the performance of electronic devices. We study TLS using millikelvin microwave loss measurements of three atomic layer deposited (ALD) oxide films--crystalline BeO…
Amorphous silicon films prepared by electron beam evaporation have systematically and substantially greater atomic density for higher thickness, higher growth temperature, and slower deposition rate, reaching the density of crystalline Si…
Nanomechanical resonators with high quality factors (\Qm{}) enable mechanics-based quantum technologies, in particular quantum sensing and quantum transduction. High-\Qm{} nanomechanical resonators in the kHz to MHz frequency range can be…
The electronic properties of thin metallic films deviate from the corresponding bulk ones when the film thickness is comparable with the wavelength of the electrons at the Fermi level due to quantum size effects (QSE). QSE are expected to…
At sub-Kelvin temperatures, two-level systems (TLS) present in amorphous dielectrics source a permittivity noise, degrading the performance of a wide range of devices using superconductive resonators such as qubits or kinetic inductance…
The low temperature properties of glass are distinct from those of crystals due to the presence of poorly understood low-energy excitations. The tunneling model proposes that these are atoms tunneling between nearby equilibria, forming…
In $e$-beam evaporated amorphous silicon ($a$-Si), the densities of two-level systems (TLS), $n_{0}$ and $\overline{P}$, determined from specific heat $C$ and internal friction $Q^{-1}$ measurements, respectively, have been shown to vary by…
This paper details the development of high-quality, c-axis oriented AlN thin films up to 2 {\mu}m thick, using sputtering on platinum-coated SOI substrates for use in piezoelectric MEMS. Our comprehensive studies illustrate how important…
Two-level systems (TLS) are an important, if not dominant, source of loss and noise for superconducting resonators such as those used in kinetic inductance detectors and some quantum information science platforms. They are similarly…
Fundamental issues of 1/f noise in quantum nanoscience are reviewed starting from basic statistical noise processes. Fundamental noise models based on two-level systems (TLS) are described. We emphasize the importance of TLSs in materials…
Low-frequency noise with the spectral density S(f)~1/f^g (f is the frequency and g~1) is a ubiquitous phenomenon, which hampers operation of many devices and circuits. A long-standing question of particular importance for electronics is…
The anomalous low-temperature properties of glasses arise from intrinsic excitable entities, so-called tunneling Two-Level-Systems (TLS), whose microscopic nature has been baffling solid-state physicists for decades. TLS have become…
This paper reports that ~10-nm-thick FeSe thin films exhibit insulator-like behavior in terms of the temperature dependence of their electrical resistivity even though bulk FeSe has a metallic electronic structure that has been confirmed by…
As-grown superconducting thin films of MgB2 were prepared by molecular beam epitaxy (MBE), and studied by X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS). Only films prepared at temperatures between 150 and 320 deg. showed…
Quench-condensed granular Al films, with normal-state sheet resistance close to 10 k$\Omega/\Box$, display strong hysteresis and ultraslow, non-exponential relaxation in the resistance when temperature is varied below 300 mK. The hysteresis…