No abstract

The production of high-n, n ∼ 300, quasi-one-dimensional (quasi-1D) strontium Rydberg atoms through two-photon excitation of selected extreme Stark states in the presence of a weak dc field is examined using a crossed laser-atom beam geometry. The dipolar polarization of the electron wave function in the product states is probed using two independent techniques. The experimental data are analyzed with a classical trajectory Monte Carlo simulation employing initial ensembles that are obtained with the aid of quantum calculations based on a two-active-electron model. Comparisons between theory and experiment highlight different characteristics of the product quasi-1D states, in particular, their large permanent dipole moments, ∼1.0 to 1.2n 2 ea 0 , where e is the electronic charge and a 0 is the Bohr radius. Such states can be engineered using pulsed electric fields to create a wide variety of target states.

Nondispersive localized Trojan wave packets with n i $ 305 moving in near-circular Bohr-like orbits are created and transported to localized near-circular Trojan states of higher n, n f $ 600, by driving with a linearly polarized sinusoidal electric field whose period is slowly increased. The protocol is remarkably efficient with over 80% of the initial atoms being transferred to the higher n states, a result confirmed by classical trajectory Monte Carlo simulations.

The efficient production of very-high-n, n ∼ 300, quasi-one-dimensional (quasi-1D) strontium Rydberg atoms through three-photon excitation of extreme Stark states in the presence of a weak dc field is demonstrated using a crossed laser-atom beam geometry. Strongly polarized quasi-1D states with large permanent dipole moments ∼1.2n 2 a.u. can be created in the beam at densities (∼10 6 cm −3) where dipole blockade effects should become important. A further advantage of three-photon excitation is that the product F states are sensitive to the presence of external fields, allowing stray fields to be reduced to very small values. The experimental data are analyzed using quantum calculations based on a two-active-electron model together with classical trajectory Monte Carlo simulations. These allow determination of the atomic dipole moments and confirm that stray fields can be reduced to 25 μV cm −1 .

We demonstrate experimentally and theoretically that the spatial distribution of high angular momentum Rydberg wave packets, and thus off-diagonal elements of the density matrix, can be probed in detail through extraction of the moments of the position distribution y λ (λ = 1, 2) from quantum beat revivals. Detailed knowledge of the position distribution allows precise manipulation of the wave packet which is demonstrated by the control of its n distribution.

Traditional pen and paper based neuropsychological tests (NPT) for cognition assessment have several challenges limiting their use. They are time consuming, expensive, and require highly trained specialists to administer. This leads to testing being available to only a small portion of the population and often with wait times of several months. In clinical practice, we have found results tend not to be integrated effectively into assessment and plans of the ordering provider. Here we compared several tests using BrainCheck (BC), a computer-based NPT battery, to traditional paper-based NPT, by evaluating individual tests as well as comparing composite scores to scores on traditional screening tools. 26 volunteers took both paper-based tests and BC. We found scores of four assessments (Ravens Matrix, Digit Symbol Modulation, Stroop Color Word Test and Trails Making A&B Test) were highly correlated. The Balance Examination and Immediate/Delayed Hopkins Verbal Learning, however, were not correlated. The BC composite score was correlated to results of the Saint Louis University Mental Status (SLUMS) exam [1], the Mini-Mental State Examination (MMSE) [2], and the Montreal Cognitive Assessment (MoCA). Our results suggest BC may offer a computer-based avenue to address the gap between basic screening and formal neuropsychological testing.

We demonstrate that circular wave packets in high Rydberg states generated by a pulsed electric field applied to extreme Stark states are characterized by a position-dependent energy gradient that leads to a correlation between the principal quantum number n and the spatial coordinate. This correlation is rather insensitive to the initial state and can be seen even in an incoherent mix of states such as is generated experimentally allowing information to be placed into, and extracted from, such wave packets. We show that detailed information on the spatial distribution of a circular wave packet can be extracted by analyzing the complex phase of its expansion coefficients.