Bulletin of the American Physical Society
38th Annual Meeting of the Division of Atomic, Molecular, and Optical Physics
Volume 52, Number 7
Tuesday–Saturday, June 5–9, 2007; Calgary, Alberta, Canada
Session X1: Hot Topics Session |
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Chair: K. Kirby, Harvard-Smithsonian Center for Astrophysics Room: TELUS Convention Centre Macleod BC |
Saturday, June 9, 2007 10:30AM - 11:06AM |
X1.00001: New Measurement of the Electron Magnetic Moment and the Fine Structure Constant . Invited Speaker: Remarkably, the famous UW measurement of the electron magnetic moment has stood since 1987.~ With QED theory, this measurement has determined the accepted value of the fine structure constant.~~ This colloquium is about a~new Harvard measurement of these fundamental constants.~ The new measurement has an uncertainty that is about six times smaller, and it shifts the values by 1.7 standard deviations.~ One electron suspended in a Penning trap is used for the new measurement, like in the old measurement.~ What is different is that the lowest quantum~levels of the spin and cyclotron motion are resolved, and the cyclotron as well as spin frequencies are determined using quantum jump spectroscopy.~ In addition, a 0.1 K Penning trap that is also a cylindrical microwave cavity is used to control the radiation field, to suppress spontaneous emission by more than a factor of 100, to control cavity shifts, and to eliminate the blackbody photons that otherwise stimulate excitations from the cyclotron ground state.~ Finally, great signal-to-noise for one-quantum transitions is obtained using electronic feedback to realize the first one-particle self-excited oscillator.~ The new methods may also allow a million times improved measurement of the 500 times smaller antiproton magnetic moment. \textbf{New Measurement of the Electron Magnetic Moment} B. Odom, D. Hanneke, B. D'Urson and G. Gabrielse, Phys. Rev. Lett. \textbf{97}, 030801 (2006). \textbf{New Determination of the Fine Structure Constant} G. Gabrielse, D. Hanneke, T. Kinoshita, M. Nio, B. Odom, Phys. Rev. Lett. 97, 030802 (2006). \textbf{AIP Physics Story of the Year }(Phys. News Update, 5 Dec. 2006) \begin{itemize} \item Science \textbf{313}, 448-449 (2006) \item Nature \textbf{442}, 516-517 (2006) \item Physics Today, 15-17 (August, 2006) \item Cern Courier (October 2006) \item New Scientist \textbf{2568}, 40-43 (2006) \item Physics World (March 2007) \end{itemize} [Preview Abstract] |
Saturday, June 9, 2007 11:06AM - 11:42AM |
X1.00002: Electron Matter Optics Invited Speaker: Our group has realized a Mach-Zehnder interferometer for electron matter waves and a source of femtosecond electron pulses. In the first experiment a highly collimated electron beam passes through three gold coated nano-fabricated gratings and reveals interference fringes. Measured dephasing processes poses limitations on the low energy use of this device. In the second experiment a femtosecond laser pump-probe experiment on a field emission tip was performed. Control of the electron emission mechanisms, which are multi-photon absorption and optical field tunneling, may be useful for the production of attosecond electron pulses. We will discuss the use of the first device to test the dispersionless nature of the Aharonov-Bohm effect and the use of the second device to test the macroscopic limit of the Aharonov-Bohm effect. [Preview Abstract] |
Saturday, June 9, 2007 11:42AM - 12:18PM |
X1.00003: Coherent manipulation of individual electronic and nuclear spin qubits in diamond Invited Speaker: The complex environment of solid-state quantum bits is generally believed to form a central challenge for solid state realizations of quantum information science. We here demonstrate how the environment of a single electronic spin can be understood, controlled, and utilized as a resource. Specifically, coherent manipulation of a single electronic spin associated with a nitrogen-vacancy (NV) center in diamond was used to probe its interactions with the $^{13}$C nuclear spin bath formed by isotopic impurities in the surrounding diamond lattice. We show that this environment is effectively separated into a set of individual, proximal $^{13}$C nuclear spins which are coupled coherently to the electron spin, and the remainder of the $^{13}$C nuclear spins, which cause the loss of coherence. A proximal nuclear spin can be addressed individually because of quantum back-action from the electron, which modifies its energy levels and magnetic moment, effectively distinguishing it from the rest of the spin bath. By manipulating the NV center via microwave and optical excitation, we demonstrate robust, room-temperature initialization of the two-qubit register formed by the electronic spin and the neearest-neighbor $^{13}$C nuclear spin. Within this register, arbitrary quantum states can be transferred between the electronic and nuclear spin, while the nuclear spin qubit can be well isolated from the electron spin, even during optical polarization and measurement of the electronic state. Finally, we observe coherent interactions between individual nuclear spins, and demonstrate that they have excellent coherence properties, approaching those of isolated atoms and ions. Such registers may be used as a basis for scalable, optically coupled quantum information systems. [Preview Abstract] |
Saturday, June 9, 2007 12:18PM - 12:54PM |
X1.00004: Producing and detecting correlated atoms in degenerate gases Invited Speaker: This talk will cover two conceptually simple experiments in which atom correlations have been demonstrated in our laboratory. In the first experiment we reproduced the atomic analog of the celebrated Hanbury Brown and Twiss experiment for photons. Correlations between atoms appear because of a constructive interference between two alternate possibilities for detecting two atoms in two detectors. We are able to reconstruct the two particle correlation function in three dimensions. This interference effect results in an enhanced probability to detect two bosons close together, provide the Bose gas is not degenerate, and a decreased probability to detect two fermions close together. The interference absent for atoms in a Bose-Einstein condensate. We have demonstrated a second type of correlation resulting from the atomic analog of four wave mixing. Two condensates are produced with a well defined relative velocity. Binary collisions (or spontaneous four wave mixing) results in atom pairs with equal and opposite momenta. Interestingly a colinear Hanbury Brown Twiss correlation is also present. We will discuss the data and our progress in their quantitative understanding. The possibility of observing a sub-Poissonian dispersion in the relative number of atoms in opposite directions will be discussed. [Preview Abstract] |
Saturday, June 9, 2007 12:54PM - 1:30PM |
X1.00005: Recording the Birth and Death of a Photon in a Cavity Invited Speaker: |
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