Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSpectroscopic imaging of single atoms within a bulk solid
49
0
0.0
(
0
)
Authors
M. Varela
Ask ChatGPT about the research
No Arabic abstract
The ability to localize, identify and measure the electronic environment of individual atoms will provide fundamental insights into many issues in materials science, physics and nanotechnology. We demonstrate, using an aberration-corrected scanning transmission microscope, the spectroscopic imaging of single La atoms inside CaTiO3. Dynamical simulations confirm that the spectroscopic information is spatially confined around the scattering atom. Furthermore we show how the depth of the atom within the crystal may be estimated.
rate research
Read More
We demonstrate sub-wavelength imaging of excitons confined to single CdTe quantum dots. By combining slit-confocal microscopy with a hemispherical solid immersion lens we simultaneously map the emission of thousands of single quantum dots with a spatial resolution of 400 nm. By analyzing the linear polarization of the quantum dot emissions at B=0T, we find that the distribution of the exchange splitting is centered at zero with a standard deviation of 0.34 meV. Similar experiments performed at B=3T give an average value of the exciton effective g factor of 3.1. This experimental approach provides an effective means to gain statistical information about the quantum dot exciton fine structure in the ensemble.
We observed quantum reflection of ultracold atoms from the attractive potential of a solid surface. Extremely dilute Bose-Einstein condensates of ^{23}Na, with peak density 10^{11}-10^{12}atoms/cm^3, confined in a weak gravito-magnetic trap were normally incident on a silicon surface. Reflection probabilities of up to 20 % were observed for incident velocities of 1-8 mm/s. The velocity dependence agrees qualitatively with the prediction for quantum reflection from the attractive Casimir-Polder potential. Atoms confined in a harmonic trap divided in half by a solid surface exhibited extended lifetime due to quantum reflection from the surface, implying a reflection probability above 50 %.
In recent torsional oscillator experiments by Kim and Chan (KC), a decrease of rotational inertia has been observed in solid 4He in porous materials and in a bulk annular channel. This observation strongly suggests the existence of non-classical rotational inertia (NCRI), i.e. superflow, in solid 4He. In order to study such a possible supersolid phase, we perform torsional oscillator experiments for cylindrical solid 4He samples. We have observed decreases of rotational inertia below 200 mK for two solid samples (pressures P = 4.1 and 3.0 MPa). The observed NCRI fraction at 70 mK is 0.14 %, which is about 1/3 of the fraction observed in the annulus by KC. Our observation is the first experimental confirmation of the possible supersolid finding by KC.
Magnetic resonance imaging (MRI) revolutionized diagnostic medicine and biomedical research by allowing a noninvasive access to spin ensembles. To enhance MRI resolution to the nanometer scale, new approaches including scanning probe methods have been used in recent years, which culminated in detection of individual spins. This allowed three-dimensional (3D) visualization of organic samples and of sophisticated spin-structures. Here, we demonstrate for the first time MRI of individual atoms on a surface. The setup, implemented in a cryogenic scanning tunneling microscope (STM), uses single-atom electron spin resonance (ESR) to achieve sub-{AA}ngstrom resolution exceeding the spatial resolution of previous experiments by one to two orders of magnitude. We find that MRI scans of different atomic species and probe tips lead to unique signatures in the resonance images. These signatures reveal the magnetic interactions between the tip and the atom, in particular magnetic dipolar and exchange interaction.
We successfully demonstrate a quantum gas microscopy using the Faraday effect which has an inherently non-destructive nature. The observed Faraday rotation angle reaches 3.0(2) degrees for a single atom. We reveal the non-destructive feature of this Faraday imaging method by comparing the detuning dependence of the Faraday signal strength with that of the photon scattering rate. We determine the atom distribution with deconvolution analysis. We also demonstrate the absorption and the dark field Faraday imaging, and reveal the different shapes of the point spread functions for these methods, which are fully explained by theoretical analysis. Our result is an important first step towards an ultimate quantum non-demolition site-resolved imaging and furthermore opens up the possibilities for quantum feedback control of a quantum many-body system with a single-site resolution.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
