We study the vortex structures of a (pseudo)spin-1/2 Fermi gas experiencing a uniform effective magnetic field in an anisotropic trap that interpolates between quasi-one dimensional (1D) and quasi-two dimensional (2D). At a fixed chemical potential, reducing the anisotropy (or equivalently increasing the attractive interactions or increasing the magnetic field) leads to instabilities towards pair density waves and vortex lattices. Reducing the chemical potential stabilizes the system. We calculate the phase diagram and explore the density and pair density.

By combining experiments and numerical simulations, we investigate the redistribution of quasimomentum in a gas of atoms trapped in an optical lattice when the lattice depth is rapidly reduced. We find that interactions lead to significant momentum redistribution on millisecond time scales, thereby invalidating previous assumptions regarding adiabaticity. Our results indicate band mapping is an inaccurate probe of the equilibrium quasimomentum distributions of interacting bosons in the single-band regime. © 2012 American Physical Society.

Single-particle imaging experiments of biomolecules at x-ray free-electron lasers (XFELs) require processing hundreds of thousands of images that contain very few x-rays. Each low-fluence image of the diffraction pattern is produced by a single, randomly oriented particle, such as a protein. We demonstrate the feasibility of recovering structural information at these extremes using low-fluence images of a randomly oriented 2D x-ray mask.

The design of the FPGA Pixel Array Detector (PAD) prototype and initial experimental results of real-time implementations of its autocorrelation function are presented. This is a pixelated 2D silicon device for detecting X-rays in X-ray Diffraction Experiments and is comprised of three layers: the diode detection and ASIC analog electronics layers connected by a massively parallel interface to a third FPGA layer consisting of a Xilinx XC6VLX550T device. A high-speed labor intensive asynchronous interface as well as a more traditional synchronous interface will be presented.

Small-angle X-ray scattering (SAXS) was performed on single-crystal chemical vapor deposition (CVD) diamonds with low nitrogen concentrations, which were fabricated by microwave plasma-assisted chemical vapor deposition at high growth rates. High optical quality undoped 500 m-thick single-crystal CVD diamonds grown without intentional nitrogen addition proved to be excellent as windows on SAXS cells, yielding parasitic scattering no more intense than a 7.5 m-thick Kapton film. A single-crystal CVD diamond window was successfully used in a high-pressure SAXS cell.

We use spectroscopic imaging scanning tunneling microscopy (SI-STM) to visualize the spatial symmetries of the electronic states that occur at the pseudogap energy scale in underdoped cuprates. We find evidence for the local intra-unit-cell electronic nematicity - by which we mean the disordered breaking of C 4v symmetry within each CuO 2 unit cell [1]. We also find that the coexisting incommensurate (smectic) electronic modulations couple to the intra-unit-cell nematicity through their 2π topological defects [2]. © 2012 Elsevier B.V. All rights reserved.

The effect of lutetium doping on the structural, electronic, and magnetic properties of epitaxial EuO thin films grown by reactive molecular-beam epitaxy is experimentally investigated. The behavior of Lu-doped EuO is contrasted with doping by lanthanum and gadolinium. All three dopants are found to behave similarly despite differences in electronic configuration and ionic size. Andreev reflection measurements on Lu-doped EuO reveal a spin-polarization of 96% in the conduction band, despite non-magnetic carriers introduced by 5% lutetium doping. © 2012 American Institute of Physics.

Direct visualization of electronic-structure symmetry within each crystalline unit cell is a new technique for complex electronic matter research (Lawler et al 2010 Nature 466 347-51, Schmidt et al 2011 New J. Phys. 13 065014, Fujita K et al 2012 J. Phys. Soc. Japan 81 011005). By studying the Bragg peaks in Fourier transforms of electronic structure images and particularly by resolving both the real and imaginary components of the Bragg amplitudes, distinct types of intra-unit-cell symmetry breaking can be studied.

We describe sensing of chemical vapors from the atmosphere using critically buckled polycrystalline silicon doubly clamped mechanical resonators coated on one side with polymethyl methacrylate (PMMA). Our method of sensing is based on stress-induced resonance frequency shifts through volumetric swelling of the 60 nm thick PMMA layer resulting in altered tension in the beams. The stress change produces shifts in the resonance frequency as large as 150 of the baseline frequency.

Employing a classical density-functional description of liquid environments, we introduce a rigorous method for the diffusion quantum Monte Carlo calculation of free energies and thermodynamic averages of solvated systems that requires neither thermodynamic sampling nor explicit solvent electrons. We find that this method yields promising results and small convergence errors for a set of test molecules. It is implemented readily and is applicable to a range of challenges in condensed matter, including the study of transition states of molecular and surface reactions in liquid environments.