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941.
We demonstrate the suppression of nuclear-spin fluctuations in an InAs quantum dot and measure the timescales of the spin narrowing effect. By initializing for tens of milliseconds with two continuous wave diode lasers, fluctuations of the nuclear spins are suppressed via the hole-assisted dynamic nuclear polarization feedback mechanism. The fluctuation narrowed state persists in the dark (absent light illumination) for well over 1 s even in the presence of a varying electron charge and spin polarization. Enhancement of the electron spin coherence time (T2*) is directly measured using coherent dark state spectroscopy. By separating the calming of the nuclear spins in time from the spin qubit operations, this method is much simpler than the spin echo coherence recovery or dynamic decoupling schemes. 相似文献
942.
We apply the density matrix renormalization group to study the phase diagram of the infinite U Hubbard model on 2- to 6-leg ladders. Where the results are largely insensitive to the ladder width, we consider the results representative of the 2D square lattice. We find a fully polarized ferromagnetic Fermi liquid phase when n, the density of electrons per site, is in the range 1>n?0.800. For n=3/4 we find an unexpected insulating checkerboard phase with coexisting bond-density order with 4 sites per unit cell and block-spin antiferromagnetic order with 8 sites per unit cell. For 3/4>n, all ladders with width >2 have unpolarized ground states. 相似文献
943.
The Nernst coefficient for the quasi-one-dimensional metal, Li{0.9}Mo{6}O{17}, is found to be among the largest known for metals (ν?500 μV/KT at T~20 K), and is enhanced in a broad range of temperature by orders of magnitude over the value expected from Boltzmann theory for carrier diffusion. A comparatively small Seebeck coefficient implies that Li{0.9}Mo{6}O{17} is bipolar with large, partial Seebeck coefficients of opposite sign. A very large thermomagnetic figure of merit, ZT~0.5, is found at high field in the range T≈35-50 K. 相似文献
944.
A Muñoz ME McConney T Kosa P Luchette L Sukhomlinova TJ White TJ Bunning B Taheri 《Optics letters》2012,37(14):2904-2906
Despite numerous efforts, continuous wave (CW) lasing in dye doped, one-dimensional (1D) photonic bandgap cholesteric liquid crystal (CLC) structures has not been previously reported, to our knowledge. Here we report on the observation of lasing in such structures under both coherent (laser) and incoherent (LED) CW light excitation. To achieve this effect, we used a 1D-photonic bandgap structure made of a polymer stabilized CLC with a pitch gradient across the cell thickness. A spectral reflectivity profile of such a CLC structure reveals local minima in the area within a photonic stopband and close to it. The realization of lasing pumped by low power CW light sources opens the possibility of all-organic, compact, tunable CW lasers for display and medical applications. 相似文献
945.
Schroeder BC Ashraf RS Thomas S White AJ Biniek L Nielsen CB Zhang W Huang Z Tuladhar PS Watkins SE Anthopoulos TD Durrant JR McCulloch I 《Chemical communications (Cambridge, England)》2012,48(62):7699-7701
Thieno[3,2-b]thienobis(silolothiophene), a new electron rich hexacyclic monomer has been synthesized and incorporated into three novel donor-acceptor low-bandgap polymers. By carefully choosing the acceptor co-monomer, the energy levels of the polymers could be modulated and high power conversion efficiencies of 5.52% were reached in OPV devices. 相似文献
946.
Wei D Grande L Chundi V White R Bower C Andrew P Ryhänen T 《Chemical communications (Cambridge, England)》2012,48(9):1239-1241
Graphite was electrochemically exfoliated in mixtures of room temperature ionic liquids and deionized water containing lithium salts to produce functionalized graphenes and such an electrochemical exfoliation technique can be directly used in making primary battery electrodes with significantly enhanced specific energy capacity. 相似文献
947.
Cowley MJ Abersfelder K White AJ Majumdar M Scheschkewitz D 《Chemical communications (Cambridge, England)》2012,48(52):6595-6597
The first magnesium, copper and zinc disilenides were prepared via transmetallation reactions of a lithium disilenide and structurally characterised. The copper and zinc derivatives show red-shifted UV/vis absorptions due to admixture of metal d-orbitals to the highest occupied molecular orbital. 相似文献
948.
A catenane host system containing integrated triazole C-H hydrogen bond donors for anion recognition
A 3,5-bis(triazole)-pyridinium motif is integrated into a catenane structural framework via chloride anion templation. The catenane host system displays a high degree of selectivity for halide anions over dihydrogen phosphate. 相似文献
949.
A homochiral diamond framework was obtained by using a secondary building unit (SBU) comprising an oxo-cluster containing 4Fe(III) and 3Mn(II) ions supported by Sb(3)O tartrate scaffolds. A fully protonated tetratopic cation, tetrakis(4-pyridyloxymethylene)methane (TPOM), acts as a template to arrange the clusters on a diamond lattice. 相似文献
950.