Bulletin of the American Physical Society
2013 Joint Meeting of the APS Division of Atomic, Molecular & Optical Physics and the CAP Division of Atomic, Molecular & Optical Physics, Canada
Volume 58, Number 6
Monday–Friday, June 3–7, 2013; Quebec City, Canada
Session H3: Rydberg Interactions and Spectroscopy |
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Chair: Georg Raithel, University of Michigan Room: 202 |
Wednesday, June 5, 2013 10:30AM - 10:42AM |
H3.00001: Magnetic trapping of circular Rydberg atoms David Anderson, Andrew Schwarzkopf, Georg Raithel Circular Rydberg atoms [1] exhibit a unique combination of properties: long lifetimes ($\sim$$\textit{n}^{5}$), large magnetic moments and angular momenta ($|\textit{m}|=\ell=\textit{n}-1$), and no first order Stark shift. Here, $\textit{n}, \ell$ and $\textit{m}$ are the principal, orbital and magnetic quantum numbers, respectively. Several of these features have made circular Rydberg atoms attractive for a number of applications including photon-atom interaction [2] and Rydberg interaction experiments. We present here the realization of a magnetic trap for circular Rydberg atoms. The Rydberg-atom trap is characterized using state-selective electric-field ionization, direct spatial imaging of the atom distributions and time-of-flight analysis of the ion signal. At room temperature, we observe 70 percent of the trapped atoms remaining after 6ms. We measure an increase of the center-of-mass trap oscillation frequency by the expected factor of $\sqrt{|m|}$. Simulations of the state-evolution of circular-state atoms in our magnetic trap, held at 300K radiation temperature, are performed and results are in good agreement with the observed phenomena.\\[4pt] [1] Randall G. Hulet and Daniel Kleppner, PRL, \textbf{51}, 1430-1433 (1983),\\[0pt] [2] M. Brune et al., PRL, \textbf{77}, 4887-4890 (1996). [Preview Abstract] |
Wednesday, June 5, 2013 10:42AM - 10:54AM |
H3.00002: Observation of spatially ordered structures in a two-dimensional Rydberg gas Peter Schauss, Marc Cheneau, Manuel Endres, Takeshi Fukuhara, Sebastian Hild, Ahmed Omran, Johannes Zeiher, Thomas Pohl, Christian Gross, Stefan Kuhr, Immanuel Bloch The ability to control interactions in ultra-cold atomic gases has paved the way for the realization of new phases of matter with short-range interactions. Rydberg atoms, which are strongly interacting via van der Waals forces, are promising candidates to gain the same amount of control over long-range interacting systems. Here we report on the experimental observation of strong correlations between laser-excited Rydberg atoms using a high-resolution optical detection scheme. The measurements reveal the emergence of spatially ordered excitation patterns with random orientation, but well-defined geometry in the high-density components of the prepared many-body state. The developed techniques might allow for the deterministic adiabatic preparation of ordered states and the investigation of their coherence properties. In combination with single-site addressing the Rydberg atom imaging techniques will enable experiments towards quantum information processing. \\[4pt] [1] P. Schau{\ss} et al., Nature 491, 87 (2012) [Preview Abstract] |
Wednesday, June 5, 2013 10:54AM - 11:06AM |
H3.00003: Steady-state crystallization of Rydberg excitations in optically driven atomic ensembles Michael Hoening, David Petrosyan, Michael Fleischhauer We study the emergence of many-body correlations in the steady state of strongly-interacting, driven dissipative systems. Specifically, we examine resonant optical excitations of Rydberg states of a confined gas of atoms interacting via long-range van der Waals potential employing numerical semiclassical Monte-Carlo simulations. At high atomic densities, all atoms within the so-called blockade radius form ``superatoms,'' each accommodating at most one Rydberg excitation. Under strong uniform driving, the saturation of superatoms leads to quasi-crystallization of Rydberg excitations whose correlations exhibit damped spatial oscillations. Main features of the system can be understood in terms of an analytically soluble rate equation model with a ``hard-rod'' interatomic potential. Moreover we discuss the effect of a finite detuning of the optical excitations for which in the ground state of the corresponding unitary system incompressible phases have been predicted. To this end we apply DMRG simulations of the steady state density matrix. [Preview Abstract] |
Wednesday, June 5, 2013 11:06AM - 11:18AM |
H3.00004: Crystallization of photons via light storage in Rydberg gases Matthias Moos, Johannes Otterbach, Dominik Muth, Michael Fleischhauer Rydberg atoms driven by light fields under conditions of electromagnetically induced transparency (EIT) can be described in terms of strongly interacting slow-light Rydberg-polaritons with tunable effective mass. In a 1D setting the physics can be described by a Luttinger liquid model. The Rydberg interaction gives rise to density-wave correlations decaying as a power law. For sufficiently strong interactions the density-wave becomes dominant, marking the onset of a quasi-crystalline photon state. We calculate the Luttinger K parameter using DMRG simulations and compare it to analytic approximations. We find that under typical slow-light conditions the interactions are too weak for crystalline order to emerge. However, adiabatically increasing the effective mass of the polaritons by turning them into stationary spin excitations allows to generate long-range crystalline order. This can be done by storing the polaritons in a stationary spin-wave. We analyze the dynamics of this process in terms of a time-dependent Luttinger theory and derive conditions for an optimal storage scenario. [Preview Abstract] |
Wednesday, June 5, 2013 11:18AM - 11:30AM |
H3.00005: Quantum Manybody Physics with Rydberg Polaritons Jonathan Simon, Alex Georgakopoulos, Albert Ryou, Jia Ningyuan Hybrid materials are an emerging frontier in condensed matter physics and quantum information science. By coupling two unlike systems, it is possible to leverage the advantages of each. Among the most famous examples are exciton-polariton gases, opto-mechanics, and Rydberg EIT; in each case photons are employed for their fast motional dynamics, in conjunction with a medium that is either nonlinear, or designed to be manipulated and read out optically. Here we describe ongoing work to produce a low-dissipation, strongly-correlated quantum material that arises from hybridizing Rydberg excitations with a 2D photon gas in a high-finesse optical resonator. This platform holds tremendous promise for studies of quantum crystallization dynamics and topological materials under pristinely controlled, easily probed conditions. [Preview Abstract] |
Wednesday, June 5, 2013 11:30AM - 11:42AM |
H3.00006: Rydberg gases at room temperature - coherent dynamics and interaction Robert Loew, Bernhard Huber, Andreas K\"olle, Thomas Baluktsian, Tilman Pfau Rydberg atoms are of great interest due to their prospects in quantum information. We present our progress on the coherent control and investigation of Rydberg atoms at room temperature. We show that we are able to drive Rabi oscillations on the nanosecond timescale to a Rydberg state by using a pulsed laser excitation and are therefore faster than the coherence time limitation given by the Doppler width [1]. By systematically investigating the dephasing of these oscillations for different atomic densities and Rydberg states we find evidence for van-der Waals interaction in thermal vapor [2]. The strength of the interaction exceeds the energy scale of thermal motion (i.e. the Doppler broadening) and therefore enables strong quantum correlations. Furthermore we present our latest results on the combination of the pulsed Rydberg excitation with a four-wave-mixing scheme and our progress towards the creation of non-classical light.\\[4pt] [1] Huber et al., PRL 107, 243001 (2011)\\[0pt] [2] Baluktsian et al., arXiv:1212.0690 [Preview Abstract] |
Wednesday, June 5, 2013 11:42AM - 11:54AM |
H3.00007: Long-range spatial correlations in a driven-dissipative system of Rydberg atoms Anzi Hu, Tony Lee, Charles Clark We consider a one-dimensional lattice of atoms with laser excitation to a Rydberg state and spontaneous emission. The atoms are coupled due to the dipole-dipole interaction of the Rydberg states. This driven-dissipative system has a broad range of non-equilibrium phases, such as bistability. Using the quantum trajectory method, we calculate the spatial correlation function throughout the parameter space. Our results show that there are long-range correlations in the bistable region, despite the low dimensionality and the presence of dissipation. We compare and contrast our results with known equilibrium results. [Preview Abstract] |
Wednesday, June 5, 2013 11:54AM - 12:06PM |
H3.00008: Measurement of time-varying electric fields near an atom chip using cold Rydberg atoms J.D. Carter, J.D.D. Martin Inhomogeneous fluctuating electric fields near metal surfaces cause undesired heating or decoherence in devices which confine atoms or ions near such a surface (microfabricated ion traps or proposed gas-phase atom/solid-state hybrid quantum systems, for example). Heating of the motion of trapped ions has been used to measure the noise spectral density of these fields but the microscopic mechanism responsible is unknown. We have implemented a complementary measurement technique using cold atoms released from an atom chip and excited to Rydberg states. The dephasing of a coherent superposition of two Rydberg states is used to measure the inhomogeneous electric field, and spin-echo techniques are used to constrain the frequency scaling of the noise spectral density. Compared to ion trap measurements, this technique has the advantage of flexibility in varying parameters such as atom-surface distance since the atoms do not need to be trapped. Field noise at levels typical for room temperature ion traps is detectable in principle, though the frequency resolution and ultimate sensitivity are inferior to ion traps. [Preview Abstract] |
Wednesday, June 5, 2013 12:06PM - 12:18PM |
H3.00009: Photoionization of Rydberg atoms in a standing-wave light field Sarah E. Anderson, Georg Raithel We investigate, experimentally and in calculations, the photoionization of Rydberg atoms in a one-dimensional optical lattice (wavelength 1064 nm). Since the Rydberg atom's size may equal or exceed the lattice period, we are able to sweep the lattice light-field maxima through the volume of the atom. We can thereby determine where the photoionization process occurs inside the atom. We measure photoionization rates for various $^{85}$Rb Rydberg nD states (45$\leq$n$\leq$65) for various positions of the light maxima relative to the center-of-mass position of the atoms. The measured rates are consistent with photoionization occurring primarily near the atom's nucleus, and not where the Rydberg electron's probability distribution is highest. We present experimental results and discuss them in context with theoretical calculations. [Preview Abstract] |
Wednesday, June 5, 2013 12:18PM - 12:30PM |
H3.00010: Laser spectroscopy of Rydberg atoms in deep optical lattices Yun-Jhih Chen, Georg Raithel We investigate the trapping of cold Rydberg atoms with a deep optical lattice. The light field of the lattice is established by coupling a 1064 nm laser into a near concentric field-enhancement cavity, which allows us to reach lattice depths up to about 1 GHz. In deep lattices Rydberg atoms exhibit a rich set of adiabatic trapping potentials that differ in many respects from those of trapped ground-state atoms. We have calculated the trapping potentials, the corresponding adiabatic states, and the associated photo-ionization rates as a function of center-of-mass position in a one GHz deep lattice. In view of ongoing experimental work, we also investigate the excitation spectra for experimentally accessible excitation schemes. We will review our theoretical results, describe the utilized experimental setup, and report on the current stage of our spectroscopic studies. We will also discuss the applications of concentric cavities in future optical lattices experiments. [Preview Abstract] |
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