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S Ejtemaee, P C Haljan
Using a laser polarization gradient, we realize 3D Sisyphus cooling of ^{171}Yb^{+} ions confined in and near the Lamb-Dicke regime in a linear Paul trap. The cooling rate and final mean motional energy of a single ion are characterized as a function of laser intensity and compared to semiclassical and quantum simulations. Sisyphus cooling is also applied to a linear string of four ions to obtain a mean energy of 1-3 quanta for all vibrational modes, an approximately order of magnitude reduction below Doppler cooled energies...
July 28, 2017: Physical Review Letters
Isidro Ferrer
The study of life and living organisms and the way in which these interact and organize to form social communities have been central to my career. I have been fascinated by biology, neurology, and neuropathology, but also by history, sociology, and art. Certain current historical, political, and social events, some occurring proximally but others affecting people in apparently distant places, have had an impact on me. Epicurus, Seneca, and Camus shared their philosophical positions which I learned from. Many scientists from various disciplines have been exciting sources of knowledge as well...
November 17, 2017: Journal of Alzheimer's Disease: JAD
Marc L De Buyzere, Thierry C Gillebert
No abstract text is available yet for this article.
November 21, 2017: European Heart Journal
Bruce J Hillman
No abstract text is available yet for this article.
September 2017: Journal of the American College of Radiology: JACR
Qing-Qing Zhang, Chuan-Lu Yang, Mei-Shan Wang, Xiao-Guang Ma, Wen-Wang Liu
The potential energy curves and transition dipole moments of 1(2)Σ(+), 2(2)Σ(+), 1(2)Π and 2(2)Π states of NH(+) cation and NH(-) anion are calculated by using multi-reference configuration interaction method and large all-electron basis sets. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear movement. The calculated spectroscopic parameters for NH(+) cation and NH(-) anion are in good agreement with available theoretical and experimental results...
October 5, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Valentin Fuster
No abstract text is available yet for this article.
May 30, 2017: Journal of the American College of Cardiology
Ivan Kozyryev, Louis Baum, Kyle Matsuda, Benjamin L Augenbraun, Loic Anderegg, Alexander P Sedlack, John M Doyle
We perform magnetically assisted Sisyphus laser cooling of the triatomic free radical strontium monohydroxide (SrOH). This is achieved with principal optical cycling in the rotationally closed P(N^{''}=1) branch of either the X[over ˜]^{2}Σ^{+}(000)↔A[over ˜]^{2}Π_{1/2}(000) or the X[over ˜]^{2}Σ^{+}(000)↔B[over ˜]^{2}Σ^{+}(000) vibronic transitions. Molecules lost into the excited vibrational states during the cooling process are repumped back through the B[over ˜](000) state for both the (100) level of the Sr-O stretching mode and the (02^{0}0) level of the bending mode...
April 28, 2017: Physical Review Letters
Alec Owens, Emil J Zak, Katy L Chubb, Sergei N Yurchenko, Jonathan Tennyson, Andrey Yachmenev
Ro-vibrational Stark-associated phenomena of small polyatomic molecules are modelled using extensive spectroscopic data generated as part of the ExoMol project. The external field Hamiltonian is built from the computed ro-vibrational line list of the molecule in question. The Hamiltonian we propose is general and suitable for any polar molecule in the presence of an electric field. By exploiting precomputed data, the often prohibitively expensive computations associated with high accuracy simulations of molecule-field interactions are avoided...
March 24, 2017: Scientific Reports
Thom Proven
No abstract text is available yet for this article.
January 2017: British Journal of Psychiatry: the Journal of Mental Science
Miquel Montero, Javier Villarroel
In this paper we consider a particular version of the random walk with restarts: random reset events which suddenly bring the system to the starting value. We analyze its relevant statistical properties, like the transition probability, and show how an equilibrium state appears. Formulas for the first-passage time, high-water marks, and other extreme statistics are also derived; we consider counting problems naturally associated with the system. Finally we indicate feasible generalizations useful for interpreting different physical effects...
September 2016: Physical Review. E
N J Fitch, M R Tarbutt
We explore a technique for decelerating molecules using a static magnetic field and optical pumping. Molecules travel through a spatially varying magnetic field and are repeatedly pumped into a weak-field seeking state as they move towards each strong field region, and into a strong-field seeking state as they move towards weak field. The method is time-independent and so is suitable for decelerating both pulsed and continuous molecular beams. By using guiding magnets at each weak field region, the beam can be simultaneously guided and decelerated...
November 18, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Andreas Dechant, Shalom Tzvi Shafier, David A Kessler, Eli Barkai
The Boltzmann-Gibbs density, a central result of equilibrium statistical mechanics, relates the energy of a system in contact with a thermal bath to its equilibrium statistics. This relation is lost for nonthermal systems such as cold atoms in optical lattices, where the heat bath is replaced with the laser beams of the lattice. We investigate in detail the stationary phase-space probability for Sisyphus cooling under harmonic confinement. In particular, we elucidate whether the total energy of the system still describes its stationary state statistics...
August 2016: Physical Review. E
M J Gullans, J Stehlik, Y-Y Liu, C Eichler, J R Petta, J M Taylor
We investigate the nonclassical states of light that emerge in a microwave resonator coupled to a periodically driven electron in a nanowire double quantum dot (DQD). Under certain drive configurations, we find that the resonator approaches a thermal state at the temperature of the surrounding substrate with a chemical potential given by a harmonic of the drive frequency. Away from these thermal regions we find regions of gain and loss, where the system can lase, or regions where the DQD acts as a single-photon source...
July 29, 2016: Physical Review Letters
Gimo M Daniel, Adrian Lv Davis, Clarke H Scholtz
Descriptions are provided for three new shade-associated species in the dung beetle genus, Sisyphus Latreille, 1807: Sisyphus umbraphilus sp. nov., Sisyphus oralensis sp. nov., and Sisyphus neobornemisszanus sp. nov. All three species are illustrated by photographs of habitus, diagnostic features, and male aedeagi. A map is provided showing their geographical distributions.
August 2, 2016: Zootaxa
Yuriy V Pershin, Sergey N Shevchenko, Franco Nori
Frequency generators are widely used in electronics. Here, we report the design and experimental realization of a memristive frequency generator employing a unique combination of only digital logic gates, a single-supply voltage and a realistic thresholdtype memristive device. In our circuit, the oscillator frequency and duty cycle are defined by the switching characteristics of the memristive device and external resistors. We demonstrate the circuit operation both experimentally, using a memristor emulator, and theoretically, using a model memristive device with threshold...
2016: Scientific Reports
Alexander Prehn, Martin Ibrügger, Rosa Glöckner, Gerhard Rempe, Martin Zeppenfeld
We demonstrate direct cooling of gaseous formaldehyde (H2CO) to the microkelvin regime. Our approach, optoelectrical Sisyphus cooling, provides a simple dissipative cooling method applicable to electrically trapped dipolar molecules. By reducing the temperature by 3 orders of magnitude and increasing the phase-space density by a factor of ∼10(4), we generate an ensemble of 3×10(5) molecules with a temperature of about 420  μK, populating a single rotational state with more than 80% purity.
February 12, 2016: Physical Review Letters
Sunil Vyas, Yuichi Kozawa, Yoko Miyamoto
We present a detailed theoretical analysis of the formation of standing waves using cylindrically polarized vector Laguerre-Gaussian (LG) beams. It is shown that complex interplay between the radial and azimuthal polarization state can be used to realize different kinds of polarization gradients with cylindrically symmetric polarization distribution. Expressions for four different cases are presented and local dynamics of spatial polarization distribution is studied. We show cylindrically symmetric Sisyphus and corkscrew type polarization gradients can be obtained from vector LG beams...
December 28, 2015: Optics Express
Marvin A Konstam, Jenica Upshaw
No abstract text is available yet for this article.
January 2016: JACC. Heart Failure
Andreas Dechant, David A Kessler, Eli Barkai
We investigate the semiclassical phase-space probability distribution P(x,p) of cold atoms in a Sisyphus cooling lattice with an additional harmonic confinement. We pose the question of whether this nonequilibrium steady state satisfies the equivalence of energy and probability. This equivalence is the foundation of Boltzmann-Gibbs and generalized thermostatic statistics, and a prerequisite for the description in terms of a temperature. At large energies, P(x,p) depends only on the Hamiltonian H(x,p) and the answer to the question is yes...
October 23, 2015: Physical Review Letters
Pauline Yzombard, Mehdi Hamamda, Sebastian Gerber, Michael Doser, Daniel Comparat
We propose a scheme for laser cooling of negatively charged molecules. We briefly summarize the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C_{2}^{-}, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photodetachment process is present, as well as Doppler laser cooling of trapped C_{2}^{-}, are also simulated...
May 29, 2015: Physical Review Letters
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