Abstract-A new parameter-free graph-morphology-based segmentation algorithm is proposed to address the problem of partitioning a 3D triangular mesh into disjoint submeshes that correspond to the physical parts of the underlying object. Curvedness, which is a rotation and translation invariant shape descriptor, is computed at every vertex in the input triangulation. Iterative graph dilation and morphological filtering of the outlier curvedness values result in multiple disjoint maximally connected submeshes such that each submesh contains a set of vertices with similar curvedness values, and vertices in disjoint submeshes have significantly different curvedness values. Experimental evaluations using the triangulations of a number of complex objects demonstrate the robustness and the efficiency of the proposed algorithm and the results prove that it compares well with a number of state-of-the-art mesh segmentation algorithms.

Designer optical control of interactions in ultracold atomic gases has wide application, from creating new quantum phases to modeling the physics of black holes. We demonstrate spatial control of interactions in a two-component cloud of 6 Li fermions, using electromagnetically induced transparency (EIT) to create a "sandwich" of resonantly and weakly interacting regions. Interaction designs are imprinted on the trapped cloud by two laser beams and manipulated with just MHz changes in the frequency of one beam. We employ radio-frequency spectroscopy to measure the imprinted 1D spatial profiles of the local mean-field interactions and to demonstrate that the tuning range of the scattering length is the same for both optical and magnetic control. All of the data are in excellent agreement with our continuum-dressed state theoretical model of optical control, which includes both the spatial and momentum dependence of the interactions. PACS numbers:Tunability of interactions in ultracold atomic gases has been achieved by exploiting magnetically controlled collisional (Feshbach) resonances [1], where the total energy of two colliding atoms in an energetically open channel is tuned into resonance with a bound dimer state in a closed channel. Optical field control offers a much richer palate, by creating designer interactions with high resolution in position, energy, momentum, and time. These techniques enable new paradigms. For example, energy resolution will provide better models of neutron matter by controlling the effective range [2, 6], while momentum resolution will permit non-zero momentum pairing in two component Fermi gases, i.e., synthetic FFLO states [4, 5]. The increased temporal resolution enables studies of nonequilibrium thermodynamics of strongly interacting gases on time scales faster than the Fermi time [6]. Spatial manipulation of interactions can be utilized to study controllable soliton emission [7], exotic quantum phases [8], long-living Bloch oscillations of matter waves [9], the physics of Hawking radiation from black holes [10], and scale-invariant dimer pairing [11]. However, optical techniques generally suffer from atom loss and heating due to spontaneous scattering, which severely limits their applicability [12][13][14][15][16][17][18][19][20].In a major breakthrough for suppressing spontaneous scattering, Bauer et al., [18] used a bound-to-bound transition in the closed channel, which is far away from the atomic resonance. To further suppress atom loss, large detunings on the bound-bound transition were employed. The large detunings limited the tunability of the scattering length a to ∆a ≃ 2 a bg , where a bg is the background scattering length. In addition, interactions were tuned by changing the intensity of the laser light, which changes the net external potential experienced by the atoms. Recently, Clark and coworkers [20] avoided this problem by using a "magic" wavelength, tuned in between D1 and D2 lines of 137 Cs atoms, to suppress the atomic polarizability and hence the change in the ...

Optical control of interactions in ultracold gases opens new fields of research by creating "designer" interactions with high spatial and temporal resolution. However, previous optical methods using single optical fields generally suffer from atom loss due to spontaneous scattering. This thesis reports new optical methods, employing two optical fields to control interactions in ultracold gases, while suppressing spontaneous scattering by quantum interference. In this dissertation, I will discuss the experimental demonstration of two optical field methods to control narrow and broad magnetic Feshbach resonances in an ultracold gas of 6 Li atoms. The narrow