Search results for "Microwave"
showing 10 items of 693 documents
Electron–cyclotron–resonance plasma heating with broadband microwave radiation: Anomalous effects
2007
Abstract Affects of microwave bandwidth on the high-charge-states of ion beams extracted from a conventional minimum- B -geometry ECR ion source are first demonstrated. The high-charge-state intensities, produced with broadband microwave radiation are observed to be factors ⩾2 than those produced with narrow bandwidth microwave radiation at the same power level.
Cross-relaxation studies with optically detected magnetic resonances in nitrogen-vacancy centers in diamond in an external magnetic field
2020
In this paper cross-relaxation between nitrogen-vacancy (NV) centers and substitutional nitrogen in a diamond crystal was studied. It was demonstrated that optically detected magnetic resonance signals (ODMR) can be used to measure these signals successfully. The ODMR were detected at axial magnetic field values around 51.2~mT in a diamond sample with a relatively high (200~ppm) nitrogen concentration. We observed transitions that involve magnetic sublevels that are split by the hyperfine interaction. Microwaves in the frequency ranges from 1.3 GHz to 1.6 GHz ($m_S=0\longrightarrow m_S=-1$ NV transitions) and from 4.1 to 4.6 GHz ($m_S=0\longrightarrow m_S=+1$ NV transitions) were used. To u…
Microwave potentials and optimal control for robust quantum gates on an atom chip
2006
We propose a two-qubit collisional phase gate that can be implemented with available atom chip technology, and present a detailed theoretical analysis of its performance. The gate is based on earlier phase gate schemes, but uses a qubit state pair with an experimentally demonstrated, very long coherence lifetime. Microwave near-fields play a key role in our implementation as a means to realize the state-dependent potentials required for conditional dynamics. Quantum control algorithms are used to optimize gate performance. We employ circuit configurations that can be built with current fabrication processes, and extensively discuss the impact of technical noise and imperfections that charac…
Coronal magnetograms of solar active regions
2004
A series of coronal magnetograms, related to the active region NOAA 9068 is derived using the effects of the quasi-transverse (QT-) propagation at microwaves. In the assumption that the product of the electron density N and the scale of magnetic divergence Ld is constant and equal to 10 18 cm −2 , the sensitivity of the measurements peaks at B(G) ≈ 180 λ −4/3 (cm), where λ is the observational wavelength. The radio maps of the Sun taken with the Solar Siberian Radio Telescope (SSRT) at λ =5 .2 cm were sampled and converted into the 2D coronal magnetograms supplying absolute values of the total magnetic vector � B in the range 10 - 30 G. Each coronal magnetogram covers the portion of the mic…
Prospects of SPIN Gyroscopes Based on Nitrogen-Vacancy Centers in Diamond
2019
This project aims to develop solid-state gyroscopes based on ensembles of negatively charged nitrogen-vacancy (NV) centers in diamond [1], [2]. The NV center is a defect formed in diamond by one substitutional nitrogen atom and an adjacent vacancy. The NV- center features a ground state with electronic spin $\mathrm{S}=1$ , which can be initialized, manipulated, and detected via convenient optical, microwave and radiofrequency transitions (Fig. 1). Nuclear spins are appealing in the context of gyroscopes because they have much smaller gyromagnetic ratios than that of the electron (by a factor of about 1000), reducing the requirements on static magnetic-field stability and homogeneity. The l…
Multiple Time Scales in the Microwave Ionization of Rydberg Atoms
1995
We investigate the time dependence of the ionization probability of Rydberg atoms driven by microwave fields, both numerically and experimentally. Our exact quantum results provide evidence for an algebraic decay law on suitably chosen time scales, a phenomenon that is considered to be the signature of nonhyperbolic scattering in unbounded classically chaotic motion.
29SiH4 and 30SiH4: Dipole moment parameters of the dyad from Stark effect observations with laser sidebands
1990
Abstract The linear Stark effect within the ν 2 ν 4 dyad of 29SiH4 and 30SiH4 has been investigated by applying the infrared sideband technique at microwave modulation frequencies. Two vibration-induced dipole moment parameters have been measured for each isotopomer on natural abundance samples.
Reconfigurable RF waveform generation using optical incoherent sources
2008
An RF waveform generator operating with incoherent broadband light is successfully implemented. Complex RF ~10 GHz bandwidth waveforms are generated by means of incoherent wavelength-to-time mapping. Our technique can be scaled to the mm-wave range.
On the Rees-Sciama effect: maps and statistics
2006
Small maps of the Rees-Sciama (RS) effect are simulated by using an appropriate N-body code and a certain ray-tracing procedure. A method designed for the statistical analysis of cosmic microwave background (CMB) maps is applied to study the resulting simulations. These techniques, recently proposed --by our team-- to consider lens deformations of the CMB, are adapted to deal with the RS effect. This effect and the deviations from Gaussianity associated to it seem to be too small to be detected in the near future. This conclusion follows from our estimation of both the RS angular power spectrum and the RS reduced n-direction correlation functions for n<7.
Impact of neutrino properties on the estimation of inflationary parameters from current and future observations
2016
We study the impact of assumptions about neutrino properties on the estimation of inflationary parameters from cosmological data, with a specific focus on the allowed contours in the $n_s/r$ plane. We study the following neutrino properties: (i) the total neutrino mass $ M_\nu =\sum_i m_i$; (ii) the number of relativistic degrees of freedom $N_{eff}$; and (iii) the neutrino hierarchy: whereas previous literature assumed 3 degenerate neutrino masses or two massless neutrino species (that do not match neutrino oscillation data), we study the cases of normal and inverted hierarchy. Our basic result is that these three neutrino properties induce $< 1 \sigma$ shift of the probability contours in…