Optical pumping and readout of bismuth hyperfine states in silicon for atomic clock applications

The push for a semiconductor-based quantum information technology has renewed interest in the spin states and optical transitions of shallow donors in silicon, including the donor bound exciton transitions in the near-infrared and the Rydberg, or hydrogenic, transitions in the mid-infrared. The deepest group V donor in silicon, bismuth, has a large zero-field ground state hyperfine splitting, comparable to that of rubidium, upon which the now-ubiquitous rubidium atomic clock time standard is based. Here we show that the ground state hyperfine populations of bismuth can be read out using the mid-infrared Rydberg transitions, analogous to the optical readout of the rubidium ground state populations upon which rubidium clock technology is based. We further use these transitions to demonstrate strong population pumping by resonant excitation of the bound exciton transitions, suggesting several possible approaches to a solid-state atomic clock using bismuth in silicon, or eventually in enriched 28Si

Si:P as a laboratory analogue for hydrogen on high magnetic field white dwarf stars

Laboratory spectroscopy of atomic hydrogen in a magnetic flux density of 10 5 T (1 gigagauss), the maximum observed on high-field magnetic white dwarfs, is impossible because practically available fields are about a thousand times less. In this regime, the cyclotron and binding energies become equal. Here we demonstrate Lyman series spectra for phosphorus impurities in silicon up to the equivalent field, which is scaled to 32.8 T by the effective mass and dielectric constant. The spectra reproduce the high-field theory for free hydrogen, with quadratic Zeeman splitting and strong mixing of spherical harmonics. They show the way for experiments on He and H 2 analogues, and for investigation of He 2, a bound molecule predicted under extreme field conditions

Interchange Slip-Running Reconnection and Sweeping SEP Beams

We present a new model to explain how particles (solar energetic particles; SEPs), accelerated at a reconnection site that is not magnetically connected to the Earth, could eventually propagate along the well-connected open flux tube. Our model is based on the results of a low-beta resistive magnetohydrodynamics simulation of a three-dimensional line-tied and initially current-free bipole, that is embedded in a non-uniform open potential field. The topology of this configuration is that of an asymmetric coronal null-point, with a closed fan surface and an open outer spine. When driven by slow photospheric shearing motions, field lines, initially fully anchored below the fan dome, reconnect at the null point, and jump to the open magnetic domain. This is the standard interchange mode as sketched and calculated in 2D. The key result in 3D is that, reconnected open field lines located in the vicinity of the outer spine, keep reconnecting continuously, across an open quasi-separatrix layer, as previously identified for non-open-null-point reconnection. The apparent slipping motion of these field lines leads to form an extended narrow magnetic flux tube at high altitude. Because of the slip-running reconnection, we conjecture that if energetic particles would be traveling through, or be accelerated inside, the diffusion region, they would be successively injected along continuously reconnecting field lines that are connected farther and farther from the spine. At the scale of the full Sun, owing to the super-radial expansion of field lines below 3 solar radii, such energetic particles could easily be injected in field lines slipping over significant distances, and could eventually reach the distant flux tube that is well-connected to the Earth

The ecological framework as part of the land and property complex of an industrial city (on the example of an urban district of Tobolsk)

In modern urban conditions with intensive industrial production affecting the life and health of people, the authorities of many cities have thought about holding activities aimed at improving the ecological component of the urban environment. One of such activities may be the creation or improvement of the ecological framework of the city. This article discusses the features of the ecological framework in the industrial city of Tobolsk. A number of tasks that are faced by the City Administration were formulated; those must be solved using sound reconstruction methods of urban territorial and functional structures. The role of the ecological framework of the urban area is considered as the possibility of avoiding the environmental problems’ emergence and preserving the ability of the territorial system as an independent land and property complex to develop

The problem of preparing a teacher for the implementation of the continuity of education of students in primary and secondary schools

Russia’s integration into the global innovation sphere, characterized by the emergence of an information society, the transition to an economy based on knowledge, the value of human capital, has determined a new vector for the development of general education. It is faced with the strategic task of updating the content, teaching methods and achieving on this basis a new quality of education in the context of maintaining its fundamental nature and at the same time meeting the modern and innovative needs of society, the state and the individual. The solution to this problem is facilitated by the comprehension and implementation of new approaches to the continuity between primary and secondary schools, which ensure the recognition of their complementary, partner coexistence in the context of strategic lines of interconnection, coordination and complementarity of goals, updated content, organization and technologies of advanced education for the optimal formation of personal, meta-subject and subject results of students in the implementation of Federal State Educational Standard of Primary General Education and Federal State Educational Standard of Basic General Education. The article proposes one of the ways to solve this problem - to increase the professional competence of teachers of primary general education and teachers of mathematics of basic school in the field of implementing the continuity of mathematical education. The solution to the stated problem is impossible without special training of teachers of primary and secondary schools, which ensures the formation of readiness to implement the continuity of mathematical education of students in primary and secondary schools in the unity of motivational, technological and reflective components

Inhomogeneous broadening of phosphorus donor lines in the far-infrared spectra of single-crystalline SiGe

The origins of line broadening in the far-infrared spectrum of phosphorus donors in SiGe are investigated. Using a combination of Fourier transform infrared FT-IR spectroscopy and time-resolved pump-probe measurements, we show that the line shapes are dominated by inhomogenous broadening. Experimental FT-IR absorbance spectra measured in the temperature range 6âÂÂ150 K are presented for three different Ge contents. Additional spectra of pure phosphorus doped silicon recorded under similar experimental conditions are presented and compared with the SiGe results. We propose a simple quantitative model to simulate the line broadening in our experimental spectra. Our model takes into account the compositional variations in the random SiGe binary alloy and its effect on the permittivity of the environment around each donor. We also show that the addition of small amounts Ge to Si single crystals has little detrimental effect on the lifetime of the excited infrared electronic energy levels, despite the observed line broadening

Isotope effect on the lifetime of the 2p(0) state in phosphorus-doped silicon

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