Related papers: Extracting superconducting parameters from surface…
Low-loss superconducting rf devices are required when used for quantum computation. Here, we present a series of measurements and simulations showing that conducting losses in the packaging of our superconducting resonator devices affect…
Microwave properties of High Temperature Superconductors (HTS) exhibit dependence on RF power levels. Effects of nonlinear phenomena causing this dependence can be modelled using lumped element circuits. Several RLC circuits to model the…
We present a simple home made solution enabling in-situ RF reflectometry measurements with a millikelvin scanning tunneling microscope (mk-STM). The additions described below were made using RF best practices following similar detection…
We develop a lower critical field (Hc1) measurement system using the third-harmonic response of an applied AC magnetic field from a solenoid coil positioned above a superconducting sample. Parameter Hc1 is measured via detection of the…
To synthesize a new superconductor which has a critical temperature, Tc, exceeding the room temperature, one needs to know what chemical components to start with. This chapter presents analysis of experimental data which allow one to draw a…
We present measurements of the microwave surface resistance Rs and the penetration depth lambda of YBCO:123 crystals. At low T obeys lambda(T) a polynomial behavior, while Rs displays a characteristic non-monotonic T-dependence. A detailed…
We grew single crystals of U6Co by the self-flux method and measured the magnetic susceptibility, resistivity, and specific heat. The magnetic susceptibility shows very small anisotropy and weak temperature dependence, indicating small…
Superconducting niobium film cavities deposited on copper substrates (Nb/Cu) have suffered from strong field-dependent surface resistance, often referred to as the Q-slope problem, since their invention. We argue that the Q-slope may not be…
We extend quantum models of nanowire surface scattering to incorporate bulk resistivity and extract an expression for the increased resistivity due to surface roughness. To learn how to improve conductivity, we calculate conductivity…
Decoherence in superconducting qubits has long been attributed to two level systems arising from the surfaces and interfaces present in real devices. A recent significant step in reducing decoherence was the replacement of superconducting…
The onset of high field Q-slope (HFQS) around 25 MV/m prevents cavities in electropolished (EP) condition from reaching high quality factors at high gradients due to the precipitation of niobium hydrides during cooldown. These hydrides are…
Quantum bits (qubits) with long coherence times are an important element for the implementation of medium- and large-scale quantum computers. In the case of superconducting planar qubits, understanding and improving qubits' quality can be…
A design of subkelvin single flux quantum (SFQ) circuits with reduced power dissipation and additional cooling of shunt resistors for superconducting qubit control circuits has been developed and characterized. We demonstrate operation of…
We consider superconductivity in the light of the quantum gravity theoretical framework introduced in [1]. In this framework, the degree of quantum delocalization depends on the geometry of the energy distribution along space. This results…
A generalized theory of open quantum systems combined with mean-field theory is used to study a superconducting wire in contact with thermal baths at different temperatures. It is shown that, depending on the temperature of the colder bath,…
The superconducting radio-frequency (SRF) community has shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. We question why some impurities improve RF performance while…
Superconducting FeSe0.8Te0.2 thin films on SrTiO3, LaAlO3 and CaF2 substrates were electrochemically etched in an ionic liquid DEME-TFSI electrolyte with a gate bias of 5 V. Superconductivity at 38 K was commonly observed on all substrates…
Nanostructured materials, critical for thermal management in semiconductor devices, exhibit a strong size dependence in thermal transport. Studying thermal resistance variation across grain boundaries is critical for designing effective…
This lecture gives an introduction to the basic physics of the electrical conductivity of metals, its temperature dependence and its limiting factors. We will then introduce the concept of surface resistance, of high relevance in…
In the past few years there has been a surge in the material science engineering in order to synthesize bulk insulating and surface metallic Topological Insulating (TI) materials. This quest is not only theoretically important but also…