Search results for "ELECTRONICS"

Investigation of the epitaxy of thin YBa2Cu3O7-delta films

1990

Abstract The degree of epitaxy of thin sputtered and laser ablated films have been investigated by Raman spectroscopy. Using the selection rules for Raman scattering for the different phonons in YBa 2 Cu 3 O 7−δ the superconducting films on SrTiO 3 and MgO are found to be epitaxially grown with the c -axis perpendicular to the substrate. On ZrO 2 the films also grow with their c -axis perpendicular to the substrate, but with randomly oriented a / b -directions in the plane of the film.

High quality superconducting titanium nitride thin film growth using infrared pulsed laser deposition

2018

Strong vacuum squeezing from bichromatically driven Kerrlike cavities: from optomechanics to superconducting circuits

2015

AbstractSqueezed light, displaying less fluctuation than vacuum in some observable, is key in the flourishing field of quantum technologies. Optical or microwave cavities containing a Kerr nonlinearity are known to potentially yield large levels of squeezing, which have been recently observed in optomechanics and nonlinear superconducting circuit platforms. Such Kerr-cavity squeezing however suffers from two fundamental drawbacks. First, optimal squeezing requires working close to turning points of a bistable cycle, which are highly unstable against noise thus rendering optimal squeezing inaccessible. Second, the light field has a macroscopic coherent component corresponding to the pump, ma…

EFFECT OF LOW-FREQUENCY NOISE ON ADIABATIC PASSAGE IN A SUPERCONDUCTING NANOCIRCUIT

2011

Recent experiments have demonstrated coherent phenomena in three-level systems based on superconducting nanocircuits. This opens the possibility to detect Stimulated Raman Adiabatic Passage (STIRAP) in artificial atoms. Low-fequency noise (often 1/f) is one of the main sources of decoherence in these systems, and we study its effect on the transfer efficiency. We propose a way to analyze low frequency fluctuations in terms of fictitious correlated fluctuations of external parameters. We discuss a specific implementation, namely the Quantronium setup of a Cooper-pair box, showing that optimizing the trade-off between efficient coupling and protection against noise may allow us to observe co…

Superconductor-Diamond Hybrid Quantum System

2016

This chapter describes recent progress on research into superconducting flux qubit, NV diamond, and superconductor-diamond hybrid quantum systems. First, we describe important physical properties of superconducting macroscopic artificial atoms i.e., the tunability of the qubit energy level spacing, the coherence property, an example of strong coupling to another quantum system such as an LC harmonic oscillator, and qubit state readout through a Josephson bifurcation amplifier. We then introduce the NV center in diamond as an intriguing candidate for quantum information processing, which offers excellent multiple accessibility via visible light, microwaves and magnetic fields. Finally, we de…

Lifetime of the superconductive state in short and long Josephson junctions

2008

We study the transient statistical properties of short and long Josephson junctions under the influence of thermal and correlated fluctuations. In particular, we investigate the lifetime of the superconductive metastable state finding the presence of noise induced phenomena. For short Josephson junctions we investigate the lifetime as a function both of the frequency of the current driving signal and the noise intensity and we find how these noise-induced effects are modified by the presence of a correlated noise source. For long Josephson junctions we integrate numerically the sine-Gordon equation calculating the lifetime as a function of the length of the junction both for inhomogeneous a…

Highly sensitive superconducting circuits at ∼700 kHz with tunable quality factors for image-current detection of single trapped antiprotons

2016

We developed highly-sensitive image-current detection systems based on superconducting toroidal coils and ultra-low noise amplifiers for non-destructive measurements of the axial frequencies (550$\sim$800$\,$kHz) of single antiprotons stored in a cryogenic multi-Penning-trap system. The unloaded superconducting tuned circuits show quality factors of up to 500$\,$000, which corresponds to a factor of 10 improvement compared to our previously used solenoidal designs. Connected to ultra-low noise amplifiers and the trap system, signal-to-noise-ratios of 30$\,$dB at quality factors of > 20$\,$000 are achieved. In addition, we have developed a superconducting switch which allows continuous tu…

Growth characteristics of sputter-deposited thin films

1996

Thin films of the heavy-fermion superconductor were deposited on various substrate materials in various orientations by means of a quasi-multilayer sputter process. Strongly (0001)-textured growth of the hexagonal compound was found for a uranium content in the range of 23% to 28% on sapphire and with perfect in-plane order on the latter substrate material. Atomic force microscopy and scanning electron microscopy revealed a Vollmer - Weber-like growth mode resulting in the development of large compressive strain in films on . As a result the electronic transport properties - in particular the temperature dependence of the resistivity - were strongly renormalized. Strong deviations from the …

Enhanced superconductivity in atomically thin TaS2

2016

The ability to exfoliate layered materials down to the single layer limit has presented the opportunity to understand how a gradual reduction in dimensionality affects the properties of bulk materials. Here we use this top–down approach to address the problem of superconductivity in the two-dimensional limit. The transport properties of electronic devices based on 2H tantalum disulfide flakes of different thicknesses are presented. We observe that superconductivity persists down to the thinnest layer investigated (3.5 nm), and interestingly, we find a pronounced enhancement in the critical temperature from 0.5 to 2.2 K as the layers are thinned down. In addition, we propose a tight-binding …

Optical near-field microscopy of light focusing through a photonic crystal flat lens

2008

We report here the direct observation by using a scanning near-field microscopy technique of the light focusing through a photonic crystal flat lens designed and fabricated to operate at optical frequencies. The lens is fabricated using a III-V semiconductor slab, and we directly visualize the propagation of the electromagnetic waves by using a scanning near-field optical microscope. We directly evidence spatially, as well as spectrally, the focusing operating regime of the lens. At last, in light of the experimental scanning near-field optical microscope pictures, we discuss the lens ability to focus light at a subwavelength scale.