Search results for "Berg"

Spectroscopy of an ultracold Rydberg gas and signatures of Rydberg–Rydberg interactions

2005

We report on experiments on Rydberg–Rydberg interaction-induced effects in a gas of 87Rb Rydberg atoms. A compact setup for two-photon continuous-wave excitation of high-lying Rydberg states out of an ultracold atomic gas is presented. The performance of the apparatus is characterized by high-resolution spectroscopy of Rydberg states. Signatures of interaction-induced effects are identified by qualitatively analysing the dependence of Rydberg excitation spectra on the intensity and the duration of the second-step laser excitation.

Determination of quantum defect for the Rydberg P series of Ca II

2019

We present an experimental investigation of the Rydberg 23 P$_{1/2}$ state of laser-cooled $^{40}$Ca$^+$ ions in a radiofrequency ion trap. Using micromotion sideband spectroscopy on a narrow quadrupole transition, the oscillating electric field at the ion position was precisely characterised, and the modulation of the Rydberg transition due to this field was minimised. From a correlated fit to this P line and previously measured P and F level energies of Ca II, we have determined the ionization energy of 95 751.916(32) $\rm {cm}^{-1}$, in agreement with the accepted value, and the quantum defect for the $n$ P$_{1/2}$ states.

Quantum Computation with Generalized Binomial States in Cavity Quantum Electrodynamics

2008

We study universal quantum computation in the cavity quantum electrodynamics (CQED) framework exploiting two orthonormal two-photon generalized binomial states as qubit and dispersive interactions of Rydberg atoms with high-$Q$ cavities. We show that an arbitrary qubit state may be generated and that controlled-NOT and 1-qubit rotation gates can be realized via standard atom-cavity interactions.

Time evolution of a pair of distinguishable interacting spins subjected to controllable and noisy magnetic fields

2017

The quantum dynamics of a $\hat{\mathbf{J}}^2=(\hat{\mathbf{j}}_1+\hat{\mathbf{j}}_2)^2$-conserving Hamiltonian model describing two coupled spins $\hat{\mathbf{j}}_1$ and $\hat{\mathbf{j}}_2$ under controllable and fluctuating time-dependent magnetic fields is investigated. Each eigenspace of $\hat{\mathbf{J}}^2$ is dynamically invariant and the Hamiltonian of the total system restricted to any one of such $(j_1+j_2)-|j_1-j_2|+1$ eigenspaces, possesses the SU(2) structure of the Hamiltonian of a single fictitious spin acted upon by the total magnetic field. We show that such a reducibility holds regardless of the time dependence of the externally applied field as well as of the statistical…

Spontaneous emission rates and energy shifts of a Rydberg rubidium atom close to an optical nanofiber

2020

The influence of an optical nanofiber on the spontaneous emission rates and Lamb shifts of a Rydberg rubidium atom in its close vicinity is investigated, in view of the implementation of a Rydberg-blockade-based quantum network.

One-dimensional twice kicked hydrogen atom

2004

Our simple theory for excitation of Rydberg atoms by two short, weak half-cycle pulses confirms the experimental data and results of previous calculations. We show that the stronger the field, the faster are the oscillations of the population .

Measurement of the Effective Weak Mixing Angle inpp¯→Z/γ*→e+e−Events

2015

We present a measurement of the fundamental parameter of the standard model, the weak mixing angle, in $p\bar{p}\rightarrow Z/\gamma^{*}\rightarrow e^{+}e^{-}$ events at a center of mass energy of 1.96 TeV, using data corresponding to 9.7 fb$^{-1}$ of integrated luminosity collected by the D0 detector at the Fermilab Tevatron. The effective weak mixing angle is extracted from the forward-backward charge asymmetry as a function of the invariant mass around the Z boson pole. The measured value of $\sin^2\theta_{\text{eff}}^{\text{$\ell$}}=0.23146 \pm 0.00047$ is the most precise measurement from light quark interactions to date, with a precision close to the best LEP and SLD results.

A Measurement of the Bbbar Forward-backward Asymmetry Using the Semileptonic Decay Into Muons

1992

UPDATE OF ELECTROWEAK PARAMETERS FROM Z DECAYS

1993

Based on 520000 fermion pairs accumulated during the first three years of data collection by the ALEPH detector at LEP, updated values of the resonance parameters of the Z are determined to be M(Z) = (91.187 +/- 0.009) GeV, GAMMA(Z) = (2.501 +/- 0.012) GeV, sigma(had)0 = (41.60 +/- 0.27) nb, and R(l) = 20.78 +/- 0.13. The corresponding number of light neutrino species is N(v) = 2.97 +/- 0.05. The forward-backward asymmetry in lepton-pair decays is used to determine the ratio of vector to axial-vector couplings of leptons: g(V)2(M(z)2)/g(A)2 (M(Z)2) = 0.0052 +/- 0.00 1 6. Combining this with ALEPH measurements of the b and c quark asymmetries and tau polarization gives sin2theta(W)eff = 0.23…

Laser spectroscopy of light muonic atoms and the nuclear charge radii

2021

The energy levels of hydrogen-like atomic systems are shifted slightly by the complex structure of the nucleus, in particular by the finite size of the nucleus. These energy shifts are vastly magnified in muonic atoms and ions, i.e. the hydrogen-like systems formed by a negative muon and a nucleus. By measuring the 2S-2P energy splitting in muonic hydrogen, muonic deuterium and muonic helium, we have been able to deduce the p, d, ^33He and ^44He nuclear charge radii to an unprecedented accuracy. These radii provide benchmarks for hadron and nuclear theories, lead to precision tests of bound-state QED in regular atoms and to a better determination of the Rydberg constant.