8 research outputs found
Quantum information processing based on P-31 nuclear spin qubits in a quasi-one-dimensional Si-28 nanowire
We suggest a new method of quantum information processing based on the
precise placing of P-31 isotope atoms in a quasi-one-dimensional Si-28 nanowire
using isotope engineering and neutron-transmutation doping of the grown
structures. In our structure, interqubit entanglement is based on the indirect
interaction of P-31 nuclear spins with electrons localized in a nanowire. This
allows one to control the coupling between distant qubits and between qubits
separated by non-qubit neighboring nodes. The suggested method enables one to
fabricate structures using present-day nanolithography. Numerical estimates
show the feasibility of the proposed device and method of operation.Comment: 7 pages, 4 figure
Structure and Spatial Distribution of Ge Nanocrystals Subjected to Fast Neutron Irradiation
The influence of fast neutron irradiation on the
structure and spatial distribution of Ge nanocrystals (NC)
embedded in an amorphous SiO2 matrix has been
studied. The investigation was conducted by means of
laser Raman Scattering (RS), High Resolution
Transmission Electron Microscopy (HR-TEM) and X-ray
photoelectron spectroscopy (XPS). The irradiation of GeNC samples by a high dose of fast neutrons lead to a
partial destruction of the nanocrystals. Full reconstruction
of crystallinity was achieved after annealing the radiation
damage at 800
0
C, which resulted in full restoration of the
RS spectrum. HR-TEM images show, however, that the
spatial distributions of Ge-NC changed as a result of
irradiation and annealing. A sharp decrease in NC
distribution towards the SiO2 surface has been observed.
This was accompanied by XPS detection of Ge oxides and
elemental Ge within both the surface and subsurface
regio
Uniform fabrication of Ge nanocrystals embedded into SiO2 film via neutron transmutation doping
Nanocrystalline 74Ge embedded SiO2 films were prepared by employing ion implantation and neutron transmutation doping methods. Transmission electron microscopy, energy dispersive x-ray spectroscopy, and photoluminescence of the obtained samples were measured. The existence of As dopants transmuted from 74Ge is significant to guarantee the uniformity and higher volume density of Ge nanocrystals by tuning the system׳s crystallinity and activating mass transfer process. It was observed that the photoluminescence intensity of Ge nanocrystals increased first then decreased with the increase of arsenic concentration. The optimized fluence of neutron transmutation doping was found to be 5.5×1017 cm−2 to achieve maximum photoluminescence emission in Ge embedded SiO2 film. This work opens a route in the three-dimensional nanofabrication of uniform Ge nanocrystals
Neutron transmutation doping effect on the optical property of germanium nanocrystals
Arsenic-doped isotopic 74Ge nanocrystals (nc-74Ge) embedded in amorphous SiO2 films were prepared by neutron transmutation doping (NTD) and the influence of the As additive on the optical properties of the samples was investigated. The optical results showed that the original nc-74Ge photoluminescence (PL) (∼620 nm) blue-shift and PL quenching could be seen by the appearance of Auger-like recombination channels, while the increase in PL was produced by neutron irradiation and a second annealing, not by the As impurities