We present a unique matter-wave interferometer whose phase scales with the cube of the time the atom spends in the interferometer. Our scheme is based on a full-loop Stern-Gerlach interferometer ...incorporating four magnetic field gradient pulses to create a state-dependent force. In contrast to typical atom interferometers that make use of laser light for the splitting and recombination of the wave packets, this realization uses no light and can therefore serve as a high-precision surface probe at very close distances.
Negatively charged nitrogen-vacancy (NV super(-)) centers in diamond have generated much recent interest for their use in sensing. The sensitivity improves when the NV ground-state microwave ...transitions are narrow, but these transitions suffer from inhomogeneous broadening, especially in high-density NV ensembles. To better understand and remove the sources of broadening, we demonstrate room-temperature spectral "hole burning" of the NV ground-state transitions. We find that hole burning removes the broadening caused by magnetic fields from super(13)C nuclei and demonstrate that it can be used for magnetic-field-insensitive thermometry.
Diamond magnetometry of superconducting thin films Waxman, A.; Schlussel, Y.; Groswasser, D. ...
Physical review. B, Condensed matter and materials physics,
02/2014, Letnik:
89, Številka:
5
Journal Article
Recenzirano
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In recent years, diamond magnetometers based on the nitrogen-vacancy (NV) center have been of considerable interest for applications at the nanoscale. An interesting application which is well suited ...for NV centers is the study of nanoscale magnetic phenomena in superconducting materials. We employ NV centers to interrogate magnetic properties of a thin-layer yttrium barium copper oxide (YBCO) superconductor. Using fluorescence-microscopy methods and samples integrated with an NV sensor on a microchip, we measure the temperature of phase transition in the layer to be 70.0(2)K and the penetration field of vortices to be 46(4) G. We observe pinning of the vortices in the layer at 65 K and estimate their density after cooling the sample in a ~ 10-G field to be 0.45(1) mu m super(-2). These measurements are done with a 10-nm-thick NV layer, so that high spatial resolution may be enabled in the future. Based on these results, we anticipate that this magnetometer could be useful for imaging the structure and dynamics of vortices. As an outlook, we present a fabrication method for a superconductor chip designed for this purpose.
Cold atoms hold much promise for the realization of quantum technologies, but still encounter many challenges. In this work we show how the fundamental Casimir-Polder force, by which atoms are ...attracted to a surface, may be temporarily suppressed by utilizing a specially designed quantum potential, which is familiar from the hydrodynamic or Bohmian reformulations of quantum mechanics. We show that when harnessing the quantum potential via suitable atomic wave-packet engineering, the absorption by the surface can be dramatically reduced. As a result, the probing time of the atoms as sensors can increase. This is proven both analytically and numerically. Furthermore, an experimental scheme is proposed for achieving the required shape for the atomic wave packet. All these may assist existing applications of cold atoms in metrology and sensing and may also enable prospective ones. Finally, these results shed light on the notion of quantum potential and its significance.
Ultracold atom magnetic field microscopy enables the probing of current flow patterns in planar structures with unprecedented sensitivity. In polycrystalline metal (gold) films, we observed ...long-range correlations forming organized patterns oriented at ±45° relative to the mean current flow, even at room temperature and at length scales larger than the diffusion length or the grain size by several orders of magnitude. The preference to form patterns at these angles is a direct consequence of universal scattering properties at defects. The observed amplitude of the current direction fluctuations scales inversely to that expected from the relative thickness variations, the grain size, and the defect concentration, all determined independently by standard methods. Ultracold atom magnetometry thus enables new insight into the interplay between disorder and transport.
To better understand the underlying fundamental physical processes in nitrogen-vacancy centers in diamond, and to realize improvements in the use of this system for technological applications, it is ...imperative to gain new insight into the origins of the apparent inhomogeneous broadening. In this work we make use of a type of spectroscopy developed specifically for this task. The pump-probe spectroscopy closely follows Doppler-free spectroscopy used in atomic vapor. We show that the origin of inhomogeneous broadening comes from local magnetic field variations in the diamond lattice.
We discuss the experimental feasibility of quantum simulation with trapped ion crystals, using magnetic field gradients. We describe a micro structured planar ion trap, which contains a central wire ...loop generating a strong magnetic gradient of about 20 T/m in an ion crystal held about 160
μ
m above the surface. On the theoretical side, we extend a proposal about spin-spin interactions via magnetic gradient induced coupling (MAGIC) J. Phys. B At. Mol. Opt. Phys.
42
, 154009 (2009). We describe aspects where planar ion traps promise novel physics: spin-spin coupling strengths of transversal eigenmodes exhibit significant advantages over the coupling schemes in longitudinal direction that have been previously investigated. With a chip device and a magnetic field coil with small inductance, a resonant enhancement of magnetic spin forces through the application of alternating magnetic field gradients is proposed. Such resonantly enhanced spin-spin coupling may be used, for instance, to create Schrödinger cat states. Finally we investigate magnetic gradient interactions in two-dimensional ion crystals, and discuss frustration effects in such two-dimensional arrangements.
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