Bulletin of the American Physical Society
46th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 60, Number 7
Monday–Friday, June 8–12, 2015; Columbus, Ohio
Session U5: Matter Wave Interferometry |
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Chair: Alexander Cronin, University of Arizona Room: Fairfield |
Friday, June 12, 2015 10:30AM - 10:42AM |
U5.00001: Atom Interferometry on a Sounding Rocket Dennis Becker, Stephan Seidel, Maike Lachmann, Ernst Rasel The universality of free fall is one of the fundamental postulates of our description of nature. The comparison of the free fall of two ultra-cold clouds of different atomic species via atom interferometry comprises a method to precisely test this assumption. By performing the experiments in a microgravity environment the sensitivity of such an atom interferometric measurement can be increased. In order to fully utilize the potential of these experiments the usage of a Bose-Einstein condensate as the initial state of the atom interferometer is necessary. As a step towards the transfer of such a system in space an atom optical experiment is currently being prepared as the scientific payload for a sounding rocket mission. This mission is aiming at the first demonstration of a Bose-Einstein condensate in space and using this quantum degenerate matter as a source for atom interferometry. The launch of the rocket is planned for 2015 from ESRANGE. This first mission will be followed by two more that extend the scientific goals to the creation of degenerate mixtures in space and simultaneous atom interferometry with two atomic species. Their success would mark a major advancement towards a precise measurement of the universality of free fall with a space-born atom interferometer. [Preview Abstract] |
Friday, June 12, 2015 10:42AM - 10:54AM |
U5.00002: Precision Measurements of Tune-out Wavelengths with an Atom Interferometer Raisa Trubko, Maxwell Gregoire, Alexander Cronin Tune-out wavelengths occur were there is a root in the dynamic polarizability between two resonances. Precision measurements of tune-out wavelengths serve as a benchmark test for atomic structure calculations of ratios of dipole matrix elements. We present a new measurement of the longest tune-out wavelength in potassium, with a preliminary result of $\lambda_{\mathrm{zero}} \quad =$ 768.9702(8) nm. We describe experimental improvements such as adding an optical cavity that allows us to reach sub-picometer precision. We discuss systematic errors due to broadband laser light and the Earths' rotation. We also show preliminary results for Rb. [Preview Abstract] |
Friday, June 12, 2015 10:54AM - 11:06AM |
U5.00003: Gradient Magnetometry in an Atomic Fountain Frank A. Narducci, Arvind K. Srinivasan, Jon P. Davis, Sara A. Desavage, Danielle A. Braje We present measurements of gradient magnetic fields using cold atoms in an atomic fountain. We collect the spectrum of driven Raman transitions at various points during the atoms' flight. For arbitrarily oriented magnetic fields, the spectrum consists of 11 peaks, whose separation is a measure of the magnetic field experienced by the atoms at the location of the Raman pulse. Ramsey interferometry ($\frac{\pi}{2}-\frac{\pi}{2}$) can be a more sensitive measure of the location of the resonances and therefore a more sensitive method to measure the fields and field gradients. However, the changing resonance frequency requires that the Raman pulses be chirped in frequency to maintain maximum contrast. Furthermore, we investigate pulse sequences involving one or more $\pi$ pulses ($\frac{\pi}{2}-\pi^N-\frac{\pi}{2}$, where N is the number of $\pi$ pulses). [Preview Abstract] |
Friday, June 12, 2015 11:06AM - 11:18AM |
U5.00004: A time domain matter-wave interferometer for testing the mass limits of quantum mechanics Jonas Rodewald, Nadine Doerre, Philipp Geyer, Philipp Haslinger, Markus Arndt We demonstrate a matter-wave interferometer in the time domain (OTIMA) as a powerful tool for testing the validity of quantum theory for large particles [1,2]. The interferometer operates in the near-field regime and utilizes three pulsed standing laser wave gratings. These periodically deplete the particle beam and imprint a periodic phase pattern on to the traversing matter waves. Depending on the particle's ionization or fragmentation cross section and optical polarizability the gratings act as absorptive masks and phase gratings with a grating period of just 80nm. The pulsed scheme of the experiment facilitates interference measurements in the time domain offering high count rate, visibility and measuring precision. Since the action of optical gratings is non-dispersive the OTIMA is well suited for interference studies on an increasingly large mass scale in the quest for novel decoherence effects, such as continuous spontaneous localization. Experiments with various organic clusters and monomers have demonstrated the functionality of the interferometer and serve as a motivation for investigating the wave-particle character of particles with masses up to 10$^{5}$ amu and beyond. \\[4pt] [1] P. Haslinger, N. D\"{o}rre, P. Geyer, J. Rodewald, S. Nimmrichter, and M. Arndt, Nat. Phys. \textbf{9}, 144 (2013).\\[0pt] [2] N. D\"{o}rre, J. Rodewald, P. Geyer, B. von Issendorff, P. Haslinger, and M. Arndt, Phys. Rev. Lett. \textbf{113}, 233001 (2014). [Preview Abstract] |
Friday, June 12, 2015 11:18AM - 11:30AM |
U5.00005: Generation and detection of neutron beams with orbital angular momentum Dmitry A. Pushin, Roman A. Barankov, Charles W. Clark, Michael G. Huber, Muhammad Arif, David G. Cory Orbital angular momentum (OAM) states of light, in which photons carry $l \hbar$ units of angular momentum along their direction of propagation, are of interest in a variety of applications.\footnote{\textit{Twisted Photons: Applications of Light with Orbital Angular Momentum}, ed. J. P. Torres and L. Torner (Wiley-VCH, 2011)} The Schr{\"o}dinger equation for massive particles also supports OAM solutions, and OAM states have been demonstrated with ultracold atoms and electrons. Here we report the first generation and detection of OAM states of neutrons, with $l$ up to 7. These are made using spiral phase plates (SPP), milled out of 6061 aluminum alloy dowels with a high-resolution computer-controlled milling machine. When a SPP is placed in one arm of a Mach-Zehnder neutron interferometer, the interferogram reveals the characteristic patterns of OAM states. Addition of angular momenta is effected by concatenation of SPPs with different values of $l$; we have found the experimental result $1 + 2 = 3$, in reasonable agreement with theory. The advent of OAM provides an additional, quantized, degree of freedom to neutron interferometry, enlarging the qubit structure available for tests of quantum information processing and foundations of quantum physics. [Preview Abstract] |
Friday, June 12, 2015 11:30AM - 11:42AM |
U5.00006: Hong-Ou-Mandel Interference with Atomic Many-Body States Rajibul Islam, Alexander Lukin, Ruichao Ma, Philipp Preiss, Matthew Rispoli, M. Eric Tai, Markus Greiner Hong-Ou-Mandel (HOM) interference experiments are a powerful probe for the indistinguishability and underlying quantum statistics of particles. In the classic HOM experiment, a pair of identical photons incident on different input ports of a beamsplitter exits via the same output port. Using the precise control and readout afforded by our quantum gas microscope, we present an implementation of this classic experiment using massive bosons in a doublewell optical potential. Identical states are prepared on each site of the doublewell and by lowering the tunnel coupling between the sites for specific times, we drive a beam splitter operation between the sites. For single-atom Fock input states, we have realized a high fidelity beamsplitter operation and observed an HOM interference contrast of \textgreater 90{\%}. By generalizing to more complex initial states on the input ports, we have been able to establish HOM experiment protocols as a robust approach towards studying the indistinguishability of many-body states as well as probe interaction-induced effects. These techniques open a path towards the measurement of purity in a quantum system and entanglement entropy in many-body states. [Preview Abstract] |
Friday, June 12, 2015 11:42AM - 11:54AM |
U5.00007: Microgravity gradiometry measurement schemes with multiple-pathway atom interferometers E. Ashwood, M. Edwards, C.W. Clark We propose a new atom-interferometric scheme for measuring the value and derivatives of the gravitational field in the microgravity environment found in the Cold-Atom Laboratory to be deployed to the International Space Station. The operation of the proposed atom interferometer consists of splitting a harmonically confined Bose-Einstein condensate into multiple pieces using a sequence of laser pulses. In a perfect harmonic oscillator potential all of the condensate pieces will come to rest at the same time. At this point, the harmonic trap is turned off. The nearly motionless condensate clouds then accumulate different phases due to their respective accelerations at different points in space. The trap is then turned back on bringing all of the clouds together at the same time at which point they are again split producing multiple interference patterns. We have simulated some of these interferometric schemes using a Lagrangian variational approximation to the 3D time--dependent Gross--Pitaevskii equation. We have used this method to facilitate rapid interferometer design and to understand how these interference patterns can be used to measure the gravitational field and its derivatives. We also compare the sensitivity of the different interferometric schemes. [Preview Abstract] |
Friday, June 12, 2015 11:54AM - 12:06PM |
U5.00008: Efficient loading of a BEC into a matter wave resonator Vyacheslav Lebedev, Changhyun Ryu, Malcolm Boshier Matter wave resonators have long attracted attention [1]. Their applications include velocity filtering, storage of BECs, and sensing. Resonant transmission of polaritons through a double barrier was recently observed [2], but cavities for cold atoms have not yet been created. The challenges here include creating suitable potentials and nonlinearity due to inter-atomic interactions. We present GPE simulation results which demonstrate that it is possible to realize a matter wave cavity resonator with the incident BEC propagating in an optical waveguide generated by the painted potential technique [3]. We will discuss the coupling of both interacting and non-interacting BECs into such resonators and the methods required to make the coupling efficient, along with experimental progress.\\[4pt] [1] V. I. Balykin and V. S. Letokhov, Appl. Phys. B 48, 517 (1989); M. Wilkens et al., Phys. Rev. A 47, 2366 (1993); I. Carusotto, Phys. Rev. A 63, 023610 (2001); T. Paul et al., Phys. Rev. Lett. 94, 020404 (2005); F. Damon et al., Phys. Rev. A 89, 053626 (2014).\\[0pt] [2] H. S. Nguyen et al., Phys. Rev. Lett. 110, 236601 (2013)\\[0pt] [3] K. Henderson et al., New J. Phys. 11, 043030 (2009); C. Ryu et al., Phys. Rev. Lett. 111, 205301 (2013); C. Ryu and M. G. Boshier, arXiv:1410.8814 (2014); [Preview Abstract] |
Friday, June 12, 2015 12:06PM - 12:18PM |
U5.00009: Shaken Lattice Interferometry Carrie Weidner, Hoon Yu, Dana Anderson This work introduces a method to perform interferometry using atoms trapped in an optical lattice. Starting at $t = 0$ with atoms in the ground state of a lattice potential $V(x) = V_0\cos[2kx + \phi(t)]$, we show that it is possible to transform from one atomic wavefunction to another by a prescribed shaking of the lattice, i.e., by an appropriately tailored time-dependent phase shift $\phi(t)$. In particular, the standard interferometer sequence of beam splitting, propagation, reflection, reverse propagation, and recombination can be achieved via a set of phase modulation operations $\{\phi_j(t)\}$. Each $\phi_j(t)$ is determined using a learning algorithm, and the split-step method calculates the wavefunction dynamics. We have numerically demonstrated an interferometer in which the shaken wavefunctions match the target states to better than $1\%$. We carried out learning using a genetic algorithm [1] and optimal control techniques [2]. The atoms remain trapped in the lattice throughout the full interferometer sequence. Thus, the approach may be suitable for use in an dynamic environment. In addition to the general principles, we discuss aspects of the experimental implementation. \\[4pt] [1] P\"{o}tting, S, et.al. PRA 64, 063613, (2001)\\[0pt] [2] Palao, J.P, et.al. PRA 77, 063412, (2009) [Preview Abstract] |
Friday, June 12, 2015 12:18PM - 12:30PM |
U5.00010: Ramsey Spectroscopy Using a Tilted 2D MOT Erin Knutson, Raghav Simha, Jonathan M. Kwolek, Frank A. Narducci We study Ramsey spectroscopy using a 2D tilted MOT. We use a tilted two-dimensional magneto-optical trap (2D MOT) to form a cold and continuous beam of Rubidium 85 atoms. The beam emerges from a pinhole where it passes through an on-resonance state preparation laser beam and then through a pair of co-propagating laser beams tuned to drive stimulated Raman transitions in the atoms. Finally, the beam passes through an on-resonance readout beam. We show that, by controlling the intensity of the Raman beams, we can make the product of the Rabi frequency and the transit time of the atoms through the laser beam equal to $\pi$ or $\pi/2$ as desired. We find a multi-peak Raman spectrum. We compare the width of the clock transition to the reciprocal of the atoms' transit time through the Raman fields. Finally, we study Ramsey spectroscopy using our system. [Preview Abstract] |
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