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The de Broglie Wave Nature of Molecules, Clusters and Nanoparticles
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2019
Stefan Gerlich, Stefan Kuhn, Armin Shayeghi, Markus Arndt
All grating types described above are known as wave-front beam splitters, since they affect different parts of the matter wavefront differently. In contrast to that, amplitude beam splitters utilize the coherent dynamics between light and atoms to impart a recoil on a part of the wave amplitude, independent of the particle position. When light is resonantly coupled to two energy levels of an atom, it will drive Rabi oscillations, i.e. coherent population oscillations between its ground state lg〉 and excited state |e〉. If the laser intensity and the duration of its interaction with the atom are chosen to be π/2=∫Ω(t)dt, the atom can be transferred into a coherent 50:50 superposition of |g〉 and |e〉. The π/2-beam splitter, thus, transforms the atomic wave function ψ ∝ |g,p〉 into ψ ∝ |g,p〉 + eiφ |e,p + ħk), where k = 2π/λL is the wave number of the incident light. This state contains maximal entanglement, i.e. inseparable quantum correlation between the internal atomic energy and its momentum. The excited state |e〉 must have absorbed a photon and received a momentum kick, while the remaining ground state |g〉 has not. In a sequence of typically four π/2 atom-laser interaction stages, one can prepare a closed atom interferometer, nowadays often referred to as Ramsey-Bordé interferometer [13].
Matterwave interferometric velocimetry of cold Rb atoms
Published in Journal of Modern Optics, 2018
Max Carey, Mohammad Belal, Matthew Himsworth, James Bateman, Tim Freegarde
The sensitivity of atom interferometry to the atomic velocities is the basis for atom interferometric measurement of accelerations, rotations, gravitational fields and their gradients, all of which are based upon the differential measurement of velocities in a back-to-back pair of velocity-sensing Ramsey interferometers which, from discrete measurements of the atomic velocity components, reveal the linear or Coriolis accelerations of atoms relative to the apparatus. The interferometer pair in each case allows the interfering paths to be closed, cancelling the path separation phase of Equation (13).
Light, the universe and everything – 12 Herculean tasks for quantum cowboys and black diamond skiers
Published in Journal of Modern Optics, 2018
Girish Agarwal, Roland E. Allen, Iva Bezděková, Robert W. Boyd, Goong Chen, Ronald Hanson, Dean L. Hawthorne, Philip Hemmer, Moochan B. Kim, Olga Kocharovskaya, David M. Lee, Sebastian K. Lidström, Suzy Lidström, Harald Losert, Helmut Maier, John W. Neuberger, Miles J. Padgett, Mark Raizen, Surjeet Rajendran, Ernst Rasel, Wolfgang P. Schleich, Marlan O. Scully, Gavriil Shchedrin, Gennady Shvets, Alexei V. Sokolov, Anatoly Svidzinsky, Ronald L. Walsworth, Rainer Weiss, Frank Wilczek, Alan E. Willner, Eli Yablonovitch, Nikolay Zheludev
Recent advances in optical atomic clocks and atom interferometry may permit a new class of gravitational wave sensors that only require a single baseline. In these interferometers, the atoms can act as inertial proof masses and their internal energy levels can also be used to measure time. In this scheme, two atom interferometers separated by a distance L (see Figure 16) are operated by a common set of lasers. The atoms are exposed to the laser light at times 0, T and 2 T. The atom–light interaction causes the atom to change its internal state, resulting in the development of a measurable phase shift. This phase shift is sensitive to the arrival time between the laser pulses. In the absence of a gravitational wave, the relative distance between atom interferometers is constant and thus the arrival times of the laser pulses do not change. In the presence of a gravitational wave, the distance between the atom interferometers modulates, resulting in a differential phase between the two atom interferometers. Since the interferometers are operated by the same laser, the noise from the laser is common and is cancelled to a high degree in the differential phase [1], while the gravitational wave signal is retained [2]. In this scheme, the cancellation of noise from the laser solely relies on the constancy of the speed of light. The atom clouds themselves need to be decoupled from environmental activity – this could be achieved by simply dropping them in free fall (ballistic interferometers) [2] or by confining them to an optical lattice whose position is well engineered to be decoupled from the environment [138]. While the atom technology is not presently as mature as optical interferometry, rapid technological developments in this field may make single baseline gravitational wave detectors suitable to search for gravitational waves in the frequency band 100 mHz–10 Hz between LIGO and LISA.