Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 59, Number 11
Friday–Saturday, October 17–18, 2014; Orem, Utah
Session K6: Atomic, Molecular and Optical Physics III |
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Chair: Dallin Durfee, Brigham Young University Room: Science Building 280 |
Saturday, October 18, 2014 1:15PM - 1:39PM |
K6.00001: Spin squeezing and Enhanced Atom-Photon Entanglement via Quantum Control Invited Speaker: Ivan Deutsch Spins are natural carriers of quantum information given their long coherence time and our ability to precisely control and measure them with magneto-optical fields. Spins in cold atomic gases provide a pristine environment for such quantum control and measurement, and thus this system can act as a test-bed for the development of quantum simulators. I will discuss the progress my group has made in collaboration with Prof. Jessen, University of Arizona, to develop the toolbox for this test-bed. Through its interactions with rf and microwave magnetic fields, whose waveforms are designed through optimal control techniques, we can implement arbitrary unitary control on the internal hyperfine spins of cesium atoms, a 16 dimensional Hilbert space (isomorphic to 4 qubits). Control of the collective spin of the ensemble of many atoms is performed via the mutual coupling of the atomic ensemble to a mode of the electromagnetic field that acts as a quantum data bus for entangling atoms with one another. Internal spin control can be used to enhance the entangling power of the atom-photon interface. This provides a mechanism for greatly enhanced spin squeezing of the atomic ensemble. [Preview Abstract] |
Saturday, October 18, 2014 1:39PM - 1:51PM |
K6.00002: Quantum dynamics for generating non-classical states Carlos Moran, Manuel Berrondo, Jean-Francois S. Van Huele We study the time evolution of quantum systems including explicit time-dependent interactions. We are particularly interested in quantum control and the generation of non-classical states. We choose non-linear Hamiltonians and apply algebraic techniques to obtain an analytic expression for the evolution operator, which we then apply to special initial states. In particular we study nonlinear oscillators in Kerr media to look for the formation of Schr\"{o}dinger-cat states from coherent states. We construct the Lie algebras corresponding to the operators of the Hamiltonian. This allows us to separate the complexity of the time-dependence from the complexity of the non-commuting operators. We also consider mean field approximations in the case that the interaction operators do not lead to a closed algebra. [Preview Abstract] |
Saturday, October 18, 2014 1:51PM - 2:03PM |
K6.00003: Characterization of an Expanding Plasma Generated in Laser-Ionized Helium Nicholas Harrison, Dan Crunkleton, Justin Peatross, Scott Bergeson An 800 nm, 35 fs laser pulse is focused using f/20 optics into a jet of helium. The peak intensity exceeding $10^{16}$ W/cm$^2$ is well above the ionization threshold for helium. Subsequently, two weak probe pulses, one passing coaxially through the track of ionized plasma and the other to the side, create an interference pattern in the far field to reveal the optical path difference induced by the presence of the plasma. The probe pulses are systematically delayed over several nanoseconds to characterize how the central plasma density decreases as a function of time, owing to radial expansion of the plasma. The expansion rate is tied to the ionized electron temperature as well as the mass of the helium ions. The ion temperature and density place this plasma just inside the strongly coupled plasma regime. We show that the electron temperature increases with ionizing laser intensity. [Preview Abstract] |
Saturday, October 18, 2014 2:03PM - 2:15PM |
K6.00004: Increasing the Coulomb coupling of an ultracold neutral plasma Mary Lyon, Scott Bergeson Ultracold neutral plasmas are strongly coupled Coulomb systems that are generated by photoionizing laser-cooled atoms close to threshold. The strong coupling parameter $\Gamma$, defined as the ratio of the nearest-neighbor Coulomb potential energy to the average ion kinetic energy, is limited at times later than $\sim$100 ns by an ultrafast, nonequilibrium relaxation of the ions. This process is called ``disorder-induced heating'' and it limits $\Gamma$ in our plasmas to order unity. A recent simulation predicted that higher values of $\Gamma$ can be realized in an ultracld plasma if the plasma ions are excited to higher ionization states. The maximum value of $\Gamma$ depends on the time at which the second ionization laser pulses arrive. I will present recent results from an experiment designed to increase the ion strong coupling of an ultracold neutral plasma by promoting the plasma ions to the second ionization state. Using laser-induced fluorescence we map out the ion velocity distribution of the Ca$^{+}$ ions in a partially doubly ionized plasma and show that the heating due to the second ionization depends on the timing of the second ionization laser pulses, as predicted by MD simulations. [Preview Abstract] |
Saturday, October 18, 2014 2:15PM - 2:27PM |
K6.00005: Precision Measurement of Laser Wavelength Using an RGB Sensor Common in Consumer Electronics Tyler Jones, Nils Otterstrom, Jarom Jackson, James Archibald, Dallin Durfee RGB sensors in consumer electronics are built to function at standards far above those needed for their typical uses. For one such sensor, the data sheet lists a 16 bit ADC and indicates that it has a temperature coefficient of only a few parts per million. These high specifications indicate that the sensors can be used in other applications, such as laser spectroscopy. Device Precision of 0.05 nm is demonstrated. Factors that influence the precision, such as etalon effects in the sensor, temperature dependence, intensity variations, and time dependence will be discussed. Funding from Brigham Young University and the National Science Foundation. [Preview Abstract] |
Saturday, October 18, 2014 2:27PM - 2:39PM |
K6.00006: Precision External Timer Adam Kingsley, Dallin Durfee In the construction of various sensors in the lab, highly accurate integration times are required. It is advantageous to have a precise external timer to run the circuitry contained in the sensor. By taking a signal in the range of megahertz down to hertz or milihertz range, it is possible to control the start and stop times for circuits. Overall this means that every time a measurement is taken it represents the same length of time. [Preview Abstract] |
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