Michael Bishof

Michael Bishof
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Michael Bishof

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Physics - Atomic Physics (6)
Quantum Physics (5)
Cosmology and Nongalactic Astrophysics (2)
Astrophysics of Galaxies (2)
Physics - Optics (1)
Nuclear Experiment (1)

Publications Authored By Michael Bishof

Background: Octupole-deformed nuclei, such as that of $^{225}$Ra, are expected to amplify observable atomic electric dipole moments (EDMs) that arise from time-reversal and parity-violating interactions in the nuclear medium. In 2015, we reported the first "proof-of-principle" measurement of the $^{225}$Ra atomic EDM. Purpose: This work reports on the first of several experimental upgrades to improve the statistical sensitivity of our $^{225}$Ra EDM measurements by orders of magnitude and evaluates systematic effects that contribute to current and future levels of experimental sensitivity. Read More

We investigate collective emission from coherently driven ultracold $ ^{88} $ Sr atoms. We perform two sets of experiments, using a strong and weak transition that are insensitive and sensitive, respectively, to atomic motion at one microKelvin. We observe highly directional forward emission with a peak intensity that is enhanced, for the strong transition, by > $ 10 ^3 $ compared to that in the transverse direction. Read More

We present a quantum-enhanced atomic clock protocol based on groups of sequentially larger Greenberger-Horne-Zeilinger (GHZ) states, that achieves the best clock stability allowed by quantum theory up to a logarithmic correction. The simultaneous interrogation of the laser phase with such a cascade of GHZ states realizes an incoherent version of the phase estimation algorithm that enables Heisenberg-limited operation while extending the Ramsey interrogation time beyond the laser noise limit. We compare the new protocol with state of the art interrogation schemes, and show that entanglement allow a significant quantum gain in the stability for short averaging time. Read More

The development of precise atomic clocks has led to many scientific and technological advances that play an increasingly important role in modern society. Shared timing information constitutes a key resource for positioning and navigation with a direct correspondence between timing accuracy and precision in applications such as the Global Positioning System (GPS). By combining precision metrology and quantum networks, we propose here a quantum, cooperative protocol for the operation of a network consisting of geographically remote optical atomic clocks. Read More

We have improved upon our previous search technique of systematically searching QSO spectra for narrow galactic H-alpha emission, which indicates a foreground galaxy within the Sloan Digital Sky Survey (SDSS) spectral fiber. We now search for H-alpha plus eight other galactic emission lines in the same manner. We have scanned the SDSS DR7 QSO catalog spectra searching for these emission lines. Read More

Interactions between atoms and lasers provide the potential for unprecedented control of quantum states. Fulfilling this potential requires detailed knowledge of frequency noise in optical oscillators with state-of-the-art stability. We demonstrate a technique that precisely measures the noise spectrum of an ultrastable laser using optical lattice-trapped $^{87}$Sr atoms as a quantum projection noise-limited reference. Read More

A search for emission lines in foreground galaxies in quasar spectra (z(gal) < z(QSO)) of the Sloan Digital Sky Survey (SDSS) data release 5 (DR5) reveals 23 examples of quasars shining through low redshift, foreground galaxies at small impact parameters (< 10 kpc). About 74,000 quasar spectra were examined by searching for narrow H{\alpha} emission lines at z < 0.38, at a flux level greater than 5 \times 10^-17 ergs cm^-2 s^-1, then confirming that other expected emission lines of the H II regions in the galaxy are detected. Read More

We observe two-body loss of ${}^3P_0$ ${}^{87}$Sr atoms trapped in a one-dimensional optical lattice. We measure loss rate coefficients for atomic samples between 1 and 6 $\mu$K that are prepared either in a single nuclear-spin-sublevel or with equal populations in two sublevels. The measured temperature and nuclear spin preparation dependence of rate coefficients agree well with calculations and reveal that rate coefficients for distinguishable atoms are only slightly enhanced over those of indistinguishable atoms. Read More

We report the observation of resolved atomic interaction sidebands (ISB) in the ${}^{87}$Sr optical clock transition when atoms at microkelvin temperatures are confined in a two-dimensional (2D) optical lattice. The ISB are a manifestation of the strong interactions that occur between atoms confined in a quasi-one-dimensional geometry and disappear when the confinement is relaxed along one dimension. The emergence of ISB is linked to the recently observed suppression of collisional frequency shifts in [1]. Read More

Optical lattice clocks have the potential for extremely high frequency stability owing to the simultaneous interrogation of many atoms, but this precision may come at the cost of systematic inaccuracy due to atomic interactions. Density-dependent frequency shifts can occur even in a clock that uses fermionic atoms if they are subject to inhomogeneous optical excitation [1, 2]. Here we present a seemingly paradoxical solution to this problem. Read More