Magnetization plateaus for spin-one bosons in optical lattices: Stern-Gerlach experiments with strongly correlated atoms

We consider insulating states of spin-one bosons in optical lattices in the presence of a weak magnetic field. For the states with more than one atom per lattice site we find a series of quantum phase transitions between states with fixed magnetization and a canted nematic phase. In the presence of a global confining potential, this unusual phase diagram leads to several novel phenomena, including the formation of magnetization plateaus. We discuss how these effects can be observed using spatially resolved spin polarization measurements.     

Nonlinear optics with stationary pulses of light

We show that the recently demonstrated technique for generating stationary pulses of light [M. Bajcsy, A. S. Zibrov, and M. D. Lukin, Nature (London) 426, 638 (2003)] can be extended to localize optical pulses in all three spatial dimensions in a resonant atomic medium. This method can be used to dramatically enhance the nonlinear interaction between weak optical pulses. In particular, we show that an efficient Kerr-like interaction between two pulses can be implemented as a sequence of several purely linear optical processes. The resulting process may enable coherent interactions between single photon pulses.     

Long-lived memory for mesoscopic quantum bits

We describe a technique to create long-lived quantum memory for quantum bits in mesoscopic systems. Specifically we show that electronic spin coherence can be reversibly mapped onto the collective state of the surrounding nuclei. The coherent transfer can be efficient and fast and it can be used, when combined with standard resonance techniques, to reversibly store coherent superpositions on the time scale of seconds. This method can also allow for "engineering" entangled states of nuclear ensembles and efficiently manipulating the stored states. We investigate the feasibility of this method through a detailed analysis of the coherence properties of the system.     

Distribution function of the sporadic E-layer screening frequency

The distribution function of the sporadic E-layer screening frequency is derived using the techniques of mathematical statistics and the physical theory of sporadic E-layer formation. The function is compared to the empirical distribution functions known from literature. The best correlation of the obtained distribution and experimental data is shown.Voronezh State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 8, pp. 872–878, August, 1991.     

Storage of light in atomic vapor

We report an experiment in which a light pulse is effectively decelerated and trapped in a vapor of Rb atoms, stored for a controlled period of time, and then released on demand. We accomplish this "storage of light" by dynamically reducing the group velocity of the light pulse to zero, so that the coherent excitation of the light is reversibly mapped into a Zeeman (spin) coherence of the Rb vapor.     

Resonant dislocation motions in NaCl crystals under EPR conditions in the Earth’s magnetic field with a radio-frequency pump field

Three resonant peaks l(ν) of dislocation paths, appearing in NaCl crystals under simultaneous exposure to the Earth’s magnetic field B Earth and an ac pump field $$\tilde B$$ have been observed in the radio-frequency range (ν ∼ 1 MHz). Each peak corresponds to a specific experimental geometry. Resonance frequencies correspond to ordinary EPR conditions in which, however, instead of the total Earth’s field, its projections onto particular crystallographic directions play part. These directions are probably related to orientations of magnetic moments at impurity centers in dislocation cores. A physical model describing well the positions all three EPR peaks l(ν) is proposed. The peak height l m is proportional to the squared amplitude of the pump field and the time t of sample exposure to crossed fields: $$l_m \propto \tilde B_m^2 t$$ . The threshold amplitude $$\tilde B_m^{th} \sim 1 \mu {\rm T}$$ of the pump field is detected, below which the effect rapidly disappears. The time of spin-lattice relaxation of radical pairs on dislocations is estimated by the threshold field $$\tilde B_m^{th}$$ level.     

A one-pot, non-catalytic approach to 1,2,4-benzothiadiazine-1,1-dioxides

Condensations of o-halo-substituted benzenesulfonyl chlorides with 2-aminopyridines and amidines may give the corresponding 1,2,4-benzothiadiazine-1,1-dioxides under mild, non-catalytic conditions in nearly quantitative yields. The successful one-pot cyclization depends on three factors: (i) the nature of the o-halogen, (ii) the electronic character of the benzene ring substituent, and (iii) the steric load around the amidine unit. O-Fluorobenzenesulfonyl chlorides bearing methylcarboxyl- or nitro-group and o-chloro- and o-bromobenzenesulfonyl chlorides bearing nitro-group are reactive enough to give the desired 1,2,4-benzothiadiazine-1,1-dioxides in a one-pot base-promoted reaction. In all other cases, open-chain sulfonylated amidine intermediates are isolated. The latter are converted to the title compounds either in the presence of potassium carbonate or upon the addition of a copper(I) catalyst.