Joe Britton

The Atacama Cosmology Telescope: CMB polarization at 200 < ℓ < 9000

We report on measurements of the cosmic microwave background (CMB) and celestial polarization at 146 GHz made with the Atacama Cosmology Telescope Polarimeter (ACTPol) in its first three months of observing. Four regions of sky covering a total of 270 square degrees were mapped with an angular resolution of 1.3. The map noise levels in the four regions are between 11 and 17 μK-arcmin. We present TT, TE, EE, TB, EB, and BB power spectra from three of these regions. The observed E-mode polarization power spectrum, displaying six acoustic peaks in the range 200 < l < 3000, is an excellent fit to the prediction of the best-fit cosmological models from WMAP9+ACT and Planck data. The polarization power spectrum, which mainly reflects primordial plasma velocity perturbations, provides an independent determination of cosmological parameters consistent with those based on the temperature power spectrum, which results mostly from primordial density perturbations. We find that without masking any point sources in the EE data at l < 9000, the Poisson tail of the EE power spectrum due to polarized point sources has an amplitude less than 2.4 μ {sup 2} at l = 3000 at 95% confidence. Finally, we report that the Crab Nebula, an important polarization calibration source at microwavemorexa0» frequencies, has 8.7% polarization with an angle of 150.7{sup o} ± 0.6{sup o} when smoothed with a 5 Gaussian beam.«xa0less

Stylus ion trap for enhanced access and sensing

Small, controllable, highly accessible quantum systems can serve as probes at the single quantum level to study multiple physical e ects, for example in quantum optics or for electric and magnetic eld sensing. The applicability of trapped atomic ions as probes is highly dependent on the measurement situation at hand and thus calls for specialized traps. Previous approaches for ion traps with enhanced optical access included traps consisting of a single ring electrode [1, 2] or two opposing endcap electrodes [2, 3]. Other possibilities are planar trap geometries, which have been investigated for Penning traps [4, 5] and rf-trap arrays [6, 7, 8]. By not having the electrodes lie in a common plane the optical access in the latter cases can be substantially increased. Here, we discuss the fabrication and experimental characterization of a novel radio-frequency (rf) ion trap geometry. It has a relatively simple structure and provides largely unrestricted optical and physical access to the ion, of up to 96% of the total 4π solid angle in one of the three traps tested. We also discuss potential applications in quantum optics and eld sensing. As a force sensor, we estimate sensitivity to forces smaller than 1 yN Hz−1/2.

Ultrasensitive detection of force and displacement using trapped ions

The ability to detect extremely small forces and nanoscale displacements is vital for disciplines such as precision spin-resonance imaging, microscopy, and tests of fundamental physical phenomena. Current force-detection sensitivity limits have surpassed 1 aN Hz(-1/2) (refs 6,7) through coupling of nanomechanical resonators to a variety of physical readout systems. Here, we demonstrate that crystals of trapped atomic ions behave as nanoscale mechanical oscillators and may form the core of exquisitely sensitive force and displacement detectors. We report the detection of forces with a sensitivity of 390 +/- 150 yN Hz(-1/2), which is more than three orders of magnitude better than existing reports using nanofabricated devices(7), and discriminate ion displacements of approximately 18 nm. Our technique is based on the excitation of tunable normal motional modes in an ion trap and detection through phase-coherent Doppler velocimetry, and should ultimately allow force detection with a sensitivity better than 1 yN Hz(-1/2) (ref. 16). Trapped-ion-based sensors could enable scientists to explore new regimes in materials science where augmented force, field and displacement sensitivity may be traded against reduced spatial resolution.

The Atacama Cosmology Telescope: Two-Season ACTPol Spectra and Parameters

Author(s): Louis, T; Grace, E; Hasselfield, M; Lungu, M; Maurin, L; Addison, GE; Ade, PAR; Aiola, S; Allison, R; Amiri, M; Angile, E; Battaglia, N; Beall, JA; De Bernardis, F; Bond, JR; Britton, J; Calabrese, E; Cho, HM; Choi, SK; Coughlin, K; Crichton, D; Crowley, K; Datta, R; Devlin, MJ; Dicker, SR; Dunkley, J; Dunner, R; Ferraro, S; Fox, AE; Gallardo, P; Gralla, M; Halpern, M; Henderson, S; Hill, JC; Hilton, GC; Hilton, M; Hincks, AD; Hlozek, R; Patty Ho, SP; Huang, Z; Hubmayr, J; Huffenberger, KM; Hughes, JP; Infante, L; Irwin, K; Kasanda, SM; Klein, J; Koopman, B; Kosowsky, A; Li, D; Madhavacheril, M; Marriage, TA; McMahon, J; Menanteau, F; Moodley, K; Munson, C; Naess, S; Nati, F; Newburgh, L; Nibarger, J; Niemack, MD; Nolta, MR; Nunez, C; Page, LA; Pappas, C; Partridge, B; Rojas, F; Schaan, E; Schmitt, BL; Sehgal, N; Sherwin, BD; Sievers, J; Simon, S; Spergel, DN; Staggs, ST; Switzer, ER; Thornton, R; Trac, H; Treu, J; Tucker, C; Engelen, AV; Ward, JT; Wollack, EJ | Abstract:

Toward spin squeezing with trapped ions

Building robust instruments capable ofmaking interferometric measurements with precision beyond the standard quantum limit remains an important goal in many metrology laboratories. We describe here the basic concepts underlying spin squeezing experiments that allow one to surpass this limit. In principle it is possible to reach the so-called Heisenberg limit, which constitutes an improvement in precision by a factorv N, where N is the number of particles on which the measurement is carried out. In particular, we focus on recent progress toward implementing spin squeezing with a cloud of beryllium ions in a Penning ion trap, via the geometric phase gate used more commonly for performing two-qubit entangling operations in quantum computing experiments.

Ions on a needle's tip - Traps with enhanced optical and physical access

The properties of single atomic ions allow them to be used as sensitive probes to measure a multitude of physical effects, ranging from light field distributions to weak force fields, for example electric or magnetic fields. However trapping and controlling ions reliably calls for a more or less encompassing electrode configuration, that depending on the realization can block a substantial amount of access to the ion. Here we present a novel radio-frequency (rf) ion trap geometry that reduces the solid angle obstructed by trap electrodes to a minimum. Since access and proper ion confinement are inherently opposing goals, we realized three different traps with access ranging from 71% to 96% of 4π to characterize the trade-offs. Fabrication, characterization, as well as promising applications of similar traps in quantum optics and field sensing are discussed.