High-temperature superfluidity of fermionic atoms in optical lattices

The experimental realizations of degenerate Bose and Fermi atomic samples have stimulated a new wave of studies of quantum many-body systems in the dilute and weakly interacting regime. The intriguing prospective of extending these studies into the domain of strongly correlated phenomena is hindered by the apparent relative weakness of atomic interactions. The effects due to interactions can, however, be enhanced if the atoms are confined in optical potentials created by standing light waves. The present letter shows that these techniques, when applied to ensembles of cold fermionic atoms, can be used to dramatically increase the transition temperature to a superfluid state and thus make it readily observable under current experimental conditions. Depending upon carefully controlled parameters, a transition to a superfluid state of Cooper pairs, antiferromagnetic states or more exotic d-wave pairing states can be induced and probed. The results of proposed experiments can provide a critical insight into the origin of high-temperature superconductivity in cuprates.Comment: 6 pages, 11 figures, RevTeX, updated versio

Raman Adiabatic Transfer of Optical States

We analyze electromagnetically induced transparency and light storage in an ensemble of atoms with multiple excited levels (multi-Lambda configuration) which are coupled to one of the ground states by quantized signal fields and to the other one via classical control fields. We present a basis transformation of atomic and optical states which reduces the analysis of the system to that of EIT in a regular 3-level configuration. We demonstrate the existence of dark state polaritons and propose a protocol to transfer quantum information from one optical mode to another by an adiabatic control of the control fields

Tracer-encapsulated pellet injector for plasma diagnostics

An injector for making solid hydrogen pellets around impurity cores has been developed for plasma transport study in large helical device. A technique has been employed for automatic loading carbon or polystyrene cores of 0.2 mm diameter from a gun magazine to a light-gas gun barrel. The injector is equipped with a cryocooler and is able to form a 3.2 mm long and 3 mm diameter cylindrical solid hydrogen pellet at 7 8 K with an impurity core in its center within 6 min and to inject it in the light-gas gun up to 1 km/s

Factors and mechanisms of productive secondary reservoirs formation in deep-lying oil and gas complexes. Article 1. Tectonophysical mechanisms of Lower Carboniferous quartzite-sandstones decompaction in the central part of the Dniprovsko-Donetska depression at the depths of more than 4.5 km

In the world, the scale of development of secondary reservoirs in decompaction rock bodies in a wide formation range is steadily increasing: from the crystalline basement of different ages of various oil and gas-bearing basins to terrigenous deposits with reduced primary porosity and carbonate formations. Development of hydrocarbon resources associated with secondary reservoirs of deep-seated complexes is the most important strategic direction of geological exploration. The results presented in this article are of fundamental importance, since they are based, firstly, mainly on the study of the core of deep-lying complexes, and secondly, on a significantly different (than in previous works) methodology (wide application of electron microscopic scanning with X-ray spectral probing and diffractometry), thirdly (and most importantly) – on a significantly different ideology. It is based on the concept of different genetic types of post-sedimentation transformations. Along with diagenesis and catagenesis, it is dislocation epigenesis and hypogene allogenesis with specific geodynamic and geothermodynamic regimes, including the special role of structural temperatures and pressures. In oil and gas-bearing basins of the continental-riftogenic (aulacogenic) type, the final stage of regional epigenesis is dislocation epigenesis with zonal and local manifestation of hypogene allogenesis. Gas and gas condensate deposits, as well as the main part of oil and heterophase deposits, are associated with this stage. The established regularities of the formation of secondary reservoirs are of particular importance for the effective development of the hydrocarbon potential of great depths

Phase diagram and excitations of a Shiba molecule

We analyze the phase diagram associated with a pair of magnetic impurities trapped in a superconducting host. The natural interplay between Kondo screening, superconductivity and exchange interactions leads to a rich array of competing phases, whose transitions are characterized by discontinuous changes of the total spin. Our analysis is based on a combination of numerical renormalization group techniques as well as semi-classical analytics. In addition to the expected screened and unscreened phases, we observe a new molecular doublet phase where the impurity spins are only partially screened by a single extended quasiparticle. Direct signatures of the various Shiba molecule states can be observed via RF spectroscopy.Comment: 13 pages, 7 figure

Threshold and linewidth of a mirrorless parametric oscillator

We analyze the above-threshold behavior of a mirrorless parametric oscillator based on resonantly enhanced four wave mixing in a coherently driven dense atomic vapor. It is shown that, in the ideal limit, an arbitrary small flux of pump photons is sufficient to reach the oscillator threshold. We demonstrate that due to the large group-velocity delays associated with coherent media, an extremely narrow oscillator linewidth is possible, making a narrow-band source of non-classical radiation feasible.Comment: revised version to appear in Phys.Rev.Lett., contains discussion on threshold conditions and operation on few-photon leve

Time-resolved Observation and Control of Superexchange Interactions with Ultracold Atoms in Optical Lattices

Quantum mechanical superexchange interactions form the basis of quantum magnetism in strongly correlated electronic media. We report on the direct measurement of superexchange interactions with ultracold atoms in optical lattices. After preparing a spin-mixture of ultracold atoms in an antiferromagnetically ordered state, we measure a coherent superexchange-mediated spin dynamics with coupling energies from 5 Hz up to 1 kHz. By dynamically modifying the potential bias between neighboring lattice sites, the magnitude and sign of the superexchange interaction can be controlled, thus allowing the system to be switched between antiferromagnetic or ferromagnetic spin interactions. We compare our findings to predictions of a two-site Bose-Hubbard model and find very good agreement, but are also able to identify corrections which can be explained by the inclusion of direct nearest-neighbor interactions.Comment: 24 pages, 7 figure