Bulletin of the American Physical Society
2018 Annual Meeting of the APS Mid-Atlantic Section
Volume 63, Number 20
Friday–Sunday, November 9–11, 2018; College Park, Maryland
Session F04: Cold Atoms |
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Chair: Michael Noel, Bryn Mawr Room: Edward St. John 2204 |
Saturday, November 10, 2018 1:30PM - 2:06PM |
F04.00001: Beat the diffraction limit with geometric potentials Invited Speaker: Yang Wang Berry's phase characterizes the geometric properties of the parameter space of a Hamiltonian, where after adiabatically following a closed path in the parameter space, the wavefunction of a system acquires a net phase. In this talk, I will explain how to use this geometric phase to overcome the diffraction limit in the optical manipulation of cold atoms. I will report our creation of a conservative optical potential with a feature size that is below λ/50. This is achieved by engineering the geometric phase associated with the dark state of a three-level atom in the EIT configuration. The ability to manipulate atoms on a subwavelength scale opens many exciting opportunities, including tunnel junctions for atomtronics applications, nearly perfect box-like atom traps, and synthesizing (arbitrary) subwavelength optical potentials. |
Saturday, November 10, 2018 2:06PM - 2:18PM |
F04.00002: A Wavefunction Microscope for Ultracold Atoms Sarthak Subhankar, Yang Wang, Tsz-Chun Tsui, Steven L Rolston, James V Porto New imaging techniques that enhance optical resolution have proven important in opening new areas of study, particularly in biological systems. The size of the features that can be optically resolved is typically limited by diffraction to the wavelength of light used to image; the field of super-resolution imaging has developed to find ways around this. We exploit the nonlinearity of an atom coupled to two laser fields to massively beat the diffraction limit by demonstrating a resolution of lambda/50. We use this sub-wavelength imaging to study the static and dynamic properties of wavefunctions of atoms in optical lattices. We use dynamic light fields to locally flip the spin composition of a narrow slice of the wavefunction to be imaged. By choosing the position of the narrow slice and selectively imaging atoms only within this slice, we can recreate the target wavefunction. The technique has fast measurement times, allowing us to study the static and dynamic properties of the atomic wavefunction. By bringing super-resolution imaging to cold atomic systems, we add a new technique to the atomic physics toolbox. This will allow for new direct probes of the atomic wavefunction in a variety of many-body systems. |
Saturday, November 10, 2018 2:18PM - 2:30PM |
F04.00003: Isotope shift spectroscopy in neutral strontium Peter Elgee, Neal Pisenti, Hirokazu Miyake, Ananya Sitaram, Nick Mennona, Gretchen K Campbell We present isotope shift measurements between 88Sr, 87Sr, 86Sr, and 84Sr, on the 1S0 -> 3P0 clock transition and the 1S0 -> 3P1 intercombination line. The two main contributions to isotope shifts come from the change in mass (the mass shift) and the change in nuclear charge radius (the field shift). Comparing bosonic measurements in a King plot analysis allow us to extract the difference in mass shift constants and the ratio of field shift constants between the two transitions without knowledge of the nuclear charge radius. Previous results have found discrepancies between measured and theoretical values for the field shift constants from a similar analysis in Ca+ [Shi, C., Gebert, F., Gorges, C. et al. Appl. Phys. B (2017) 123: 2], which this work could help resolve. In addition, recent proposals have suggested looking for nonlinearities in King plots as a signature of new physics [J.C. Berengut et al., Phys. Rev. Lett. 120, 091801 (2018)]. Along with proper incorporation of the hyperfine structure of the fermionic isotope, or with new measurements in one of the unstable isotopes of Sr, this work could help provide limits on these theories. |
Saturday, November 10, 2018 2:30PM - 3:06PM |
F04.00004: Measurement induced dynamics and defect stabilization in spinor condensates Invited Speaker: Hilary M. Hurst Understanding system-reservoir dynamics in many-body physics is a new frontier. An external environment can be thought of as a `measurement reservoir' which extracts information about the quantum system. Weak (i.e. minimally destructive) measurements provide a time-resolved but noisy record of system evolution. In this talk, we propose using weak measurement and feedback to probe and manipulate spinor Bose-Einstein condensates, focusing on the trade-off between usable information obtained from measurement and the effect of measurement on the system (quantum backaction). As a prototype example, we consider the dynamics of a domain wall in a two-component BEC and show that quantum backaction due to measurement causes two primary effects: domain wall diffusion and overall heating. The system dynamics and signal-to-noise ratio depend on the choice of measurement observable. We describe a feedback protocol to create and stabilize a domain wall in the regime where domain walls are unstable, giving a prototype example of Hamiltonian engineering using measurement and feedback. |
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