16,198 research outputs found
Experimental Test of Quantum Jarzynski Equality with a Trapped Ion System
The past two decades witnessed important developments in the field of
non-equilibrium statistical mechanics. Among these developments, the Jarzynski
equality, being a milestone following the landmark work of Clausius and Kelvin,
stands out. The Jarzynski equality relates the free energy difference between
two equilibrium states and the work done on the system through far from
equilibrium processes. While experimental tests of the equality have been
performed in classical regime, the verification of the quantum Jarzynski
equality has not yet been fully demonstrated due to experimental challenges.
Here, we report an experimental test of the quantum Jarzynski equality with a
single \Yb ion trapped in a harmonic potential. We perform projective
measurements to obtain phonon distributions of the initial thermal state.
Following that we apply the laser induced force on the projected energy
eigenstate, and find transition probabilities to final energy eigenstates after
the work is done. By varying the speed of applying the force from equilibrium
to far-from equilibrium regime, we verified the quantum Jarzynski equality in
an isolated system.Comment: 18 pages, 4 figures, 1 tabl
Tephrostratigraphic investigations of the Late Pleistocene-Holocene deposits in the northwestern Pacific Ocean and adjacent seas (Okhotsk and Bering)
STM and RHEED study of the Si(001)-c(8x8) surface
The Si(001) surface deoxidized by short annealing at T~925C in the ultrahigh
vacuum molecular beam epitaxy chamber has been in situ investigated by high
resolution scanning tunnelling microscopy (STM) and reflected high energy
electron diffraction (RHEED). RHEED patterns corresponding to (2x1) and (4x4)
structures were observed during sample treatment. The (4x4) reconstruction
arose at T<600C after annealing. The reconstruction was observed to be
reversible: the (4x4) structure turned into the (2x1) one at T>600C, the (4x4)
structure appeared again at recurring cooling. The c(8x8) reconstruction was
revealed by STM at room temperature on the same samples. A fraction of the
surface area covered by the c(8x8) structure decreased as the sample cooling
rate was reduced. The (2x1) structure was observed on the surface free of the
c(8x8) one. The c(8x8) structure has been evidenced to manifest itself as the
(4x4) one in the RHEED patterns. A model of the c(8x8) structure formation has
been built on the basis of the STM data. Origin of the high-order structure on
the Si(001) surface and its connection with the epinucleation phenomenon are
discussed.Comment: 26 pages, 12 figure
Preparation and thermal properties of mesoporous silica/phenolic resin nanocomposites via in situ polymerization
In order to enhance the adhesion between inorganic particles and polymer matrix, in this paper, the mesoporous silica SBA-15 material was synthesized by the sol-gel method. The surface of SBA-15 was modified using γ-glycidyloxypropyltrimethoxysilane (GOTMS) as a coupling agent, and then mesoporous silica/phenolic resin (SBA-15/PF) nanocomposites were prepared via in situ polymerization. The structural parameters and physical properties of SBA-15, SBA-15-GOTMS (SBA-15 surface treated using GOTMS as coupling agents) and E-SBA-15/PF (SBA-15/PF nanocomposites extracted using ethanol as solvent) were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The thermal properties of the nanocomposites were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results demonstrated that the GOTMS were successfully grafted onto the surface of SBA-15, and chemical bonds between PF and SBA-15-GOTMS were formed after in situ polymerization. In addition, it is found that the in situ polymerization method has great effects on the textural parameters of SBA-15. The results also showed that the glass transition temperatures and thermal stability of the PF nanocomposites were obviously enhanced as compared with the pure PF at silica contents between 1–3 wt%, due to the uniform dispersion of the modified SBA-15 in the matrix
Possible Multiple Gap Superconductivity with Line Nodes in Heavily Hole-Doped Superconductor KFe2As2 Studied by 75As-NQR and Specific Heat
We report the 75As nuclear quadrupole resonance (NQR) and specific heat
measurements of the heavily hole-doped superconductor KFe2As2 (Tc = 3.5 K). The
spin-lattice relaxation rate 1/T1 in the superconducting state exhibits quite
gradual temperature dependence with no coherence peak below Tc. The
quasi-particle specific heat C_QP/T shows small specific heat jump which is
about 30% of electronic specific heat coefficient just below Tc. In addition,
it suggests the existence of low-energy quasi-particle excitation at the lowest
measurement temperature T = 0.4 K \simeq Tc/10. These temperature dependence of
1/T1 and C_QP/T can be explained by multiple nodal superconducting gap scenario
rather than multiple fully-gapped s_\pm-wave one within simple gap analysis.Comment: 5 pages, 5 figures, to be published in J. Phys. Soc. Jpn. No.8 issue
(2009
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