Atomic Physics Latest Preprints | 2019-06-10
Atomic Physics
Spin-alignment noise in atomic vapor (1906.03163v1)
A. A. Fomin, M. Yu. Petrov, G. G. Kozlov, M. M. Glazov, I. I. Ryzhov, M. V. Balabas, V. S. Zapasskii
2019-06-07
In the conventional spin noise spectroscopy, the probe laser light monitors fluctuations of the spin orientation of a paramagnet revealed as fluctuations of its gyrotropy, i.e., circular birefringence. For spins larger than 1/2, there exists spin arrangement of a higher order --- the so-called spin alignment --- which also exhibits spontaneous fluctuations. We show theoretically and experimentally that alignment fluctuations manifest themselves as the noise of the linear birefringence. In a magnetic field, the spin-alignment fluctuations, in contrast to those of spin orientation, show up as the noise of the probe-beam ellipticity at the double Larmor frequency, with the most efficient geometry of its observation being the Faraday configuration with the light propagating along the magnetic field. We have detected the spin-alignment noise in a cesium-vapor cell probed at the wavelength of D2 line (852.3 nm). The magnetic-field and polarization dependence of the ellipticity noise are in full agreement with the developed theory.
Dicke subradiance and thermal decoherence (1906.02918v1)
P. Weiss, A. Cipris, M. O. Araújo, R. Kaiser, W. Guerin
2019-06-07
Subradiance is the cooperative inhibition of the radiation by several emitters coupled to the same electromagnetic modes. It has been predicted by Dicke in 1954 and only recently observed in cold atomic vapors. Here we address the question to what extend this cooperative effect survives outside the limit of frozen two-level systems by studying the subradiant decay in an ensemble of cold atoms as a function of the temperature. Experimentally, we observe only a slight decrease of the subradiant decay time when increasing the temperature up to several millikelvins, and in particular we measure subradiant decay rates that are much smaller than the Doppler broadening. This demonstrates that subradiance is surprisingly robust against thermal decoherence. The numerical simulations are in good agreement and allow us to extrapolate the behavior of subradiance at higher temperatures.
Thermodynamics of Bose gases from functional renormalization with a hydrodynamic low-energy effective action (1902.07135v2)
Felipe Isaule, Michael C. Birse, Niels R. Walet
2019-02-19
The functional renormalization group for the effective action is used to construct an effective hydrodynamic description of weakly interacting Bose gases. We employ a scale-dependent parametrization of the boson fields developed previously to start the renormalization evolution in a Cartesian representation at high momenta and interpolate to an amplitude-phase one in the low-momentum regime. This technique is applied to Bose gases in one, two and three dimensions, where we study thermodynamic quantities such as the pressure and energy per particle. The interpolation leads to a very natural description of the Goldstone modes in the physical limit, and compares well to analytic and Monte-Carlo simulations at zero temperature. The results show that our method improves aspects of the description of low-dimensional systems, with stable results for the superfluid phase in two dimensions and even in one dimension.
Deep laser cooling and efficient magnetic compression of molecules (1812.07926v2)
L. Caldwell, J. A. Devlin, H. J. Williams, N. J. Fitch, E. A. Hinds, B. E. Sauer, M. R. Tarbutt
2018-12-19
We introduce a scheme for deep laser cooling of molecules based on robust dark states at zero velocity. By simulating this scheme, we show it to be a widely applicable method that can reach the recoil limit or below. We demonstrate and characterise the method experimentally, reaching a temperature of 5.4(7)
K. We solve a general problem of measuring low temperatures for large clouds by rotating the phase-space distribution and then directly imaging the complete velocity distribution. Using the same phase-space rotation method, we rapidly compress the cloud. Applying the cooling method a second time, we compress both the position and velocity distributions.
Optical waveguiding by atomic entanglement in multilevel atom arrays (1906.02204v1)
A. Asenjo-Garcia, H. J. Kimble, D. E. Chang
2019-06-05
The optical properties of sub-wavelength arrays of atoms or other quantum emitters have attracted significant interest recently. For example, the strong constructive or destructive interference of emitted light enables arrays to function as nearly perfect mirrors, support topological edge states, and allow for exponentially better quantum memories. In these proposals, the assumed atomic structure was simple, consisting of a unique electronic ground state. Within linear optics, the system is then equivalent to a periodic array of classical dielectric particles, whose periodicity supports the emergence of guided modes. However, it has not been known whether such phenomena persist in the presence of hyperfine structure, as exhibited by most quantum emitters. Here, we show that waveguiding can arise from rich atomic entanglement as a quantum many-body effect, and elucidate the necessary conditions. Our work represents a significant step forward in understanding collective effects in arrays of atoms with realistic electronic structure.
The Momentum Representation of the Hydrogen Atom in Paraboloidal Coordinates (1906.02375v1)
John R. Lombardi
2019-06-05
We examine the procedure to construct the variables of use for the momentum representation in quantum mechanics. The momentum variables must be chosen properly conjugate to the corresponding position space variables, such that valid uncertainty relationships are maintained. We then apply such considerations to the hydrogen atom to obtain the momentum space wave functions corresponding to the position space functions in paraboloidal coordinates. The advantages and disadvantages of employing the momentum representation are explored.
Multipolar and higher-order lattice shifts in the Sr and Mg clocks (1906.02024v1)
Fang-Fei Wu, Yong-Bo Tang, Ting-Yun Shi, Li-Yan Tang
2019-06-05
The progress in optical clock with uncertainty at a level of
requires unprecedented precision in estimating the contribution of multipolar and higher-order effects of atom-field interactions. Previous theoretical and experimental results of dynamic multipolar polarizabilities and hyperpolarizabilities at the 813 nm magic wavelength of the Sr clock differ substantially. We employ the sum-over-states method to calculate dynamic multipolar polarizabilities and hyperpolarizabilities for the Sr and Mg clocks. Our differential dynamic hyperpolarizability at the magic wavelength of 813.4280(5) nm for the Sr clock is
a.u., which agrees well with the recent theoretical and measurement results. Our differential multipolar polarizability of the Sr clock is
a.u., which is consistent with the theoretical work of Porsev {\em et al.} [Phys. Rev. Lett. 120, 063204 (2018)], but different from recent measurement of Ushijima {\em et al.} [Phys. Rev. Lett. 121, 263202 (2018)]. In addition, the lattice light shifts as the detuning and trap depth changed are studied in detail by using present multipolar polarizability and hyperpolarizability. It illustrates that for the Mg clock, there exists a distinctive operational lattice depth of
that allows the total light shift reduced to less than
over the trap depth variation of
.
Multimode collective scattering of light in free space by a cold atomic gas (1906.02000v1)
R. Ayllon, J. T. Mendonça, A. T. Gisbert, N. Piovella, G. R. M. Robb
2019-06-05
We have studied collective recoil lasing by a cold atomic gas, scattering photons from an incident laser into many radiation modes in free space. The model consists of a system of classical equations for the atomic motion of N atoms, where the radiation field has been adiabatically eliminated. We performed numerical simulations using a molecular dynamics code, Pretty Efficient Parallel Coulomb Solver or PEPC, to track the trajectories of the atoms. These simulations show the formation of an atomic density grating and collective enhancement of scattered light, both of which are sensitive to the shape and orientation of the atomic cloud. In the case of an initially circular cloud, the dynamical evolution of the cloud shape plays an important role in the development of the density grating and collective scattering. The ability to use efficient molecular dynamics codes will be a useful tool for the study of the multimode interaction between light and cold gases.
factor of the 
state of middle-
boronlike ions (1812.06431v2)
V. A. Agababaev, D. A. Glazov, A. V. Volotka, D. V. Zinenko, V. M. Shabaev, G. Plunien
2018-12-16
Theoretical \emph{g}-factor calculations for the first excited \exst state of boronlike ions in the range
Stochastic amplitude fluctuations of bosonic dark matter and revised constraints on linear couplings (1905.13650v2)
Gary P. Centers, John W. Blanchard, Jan Conrad, Nataniel L. Figueroa, Antoine Garcon, Alexander V. Gramolin, Derek F. Jackson Kimball, Matthew Lawson, Bart Pelssers, Joeseph A. Smiga, Yevgeny Stadnik, Alexander O. Sushkov, Arne Wickenbrock, Dmitry Budker, Andrei Derevianko
2019-05-31
If the dark matter is composed of virialized particles with mass
eV, it is well described as a classical bosonic field. This field is stochastic in nature, where the field oscillation amplitude fluctuates following a Rayleigh distribution. Most experimental searches have been in the regime
eV, where it is reasonable to assume a fixed field oscillation amplitude determined by the average local dark matter energy density. However, several direct-detection experiments are searching in the ultra-light mass regime where the dark matter field coherence time greatly exceeds the measurement time and the field oscillation amplitude is uncertain. We show that the corresponding laboratory constraints of bosonic dark matter field couplings to standard model particles are overestimated by as much as an order of magnitude.
