This thesis presents the experimental and theoretical studies of the survival resonances in a dissipative atom-optics system, and their applications. We demonstrate this resonant phenomenon by using an alternative approach to the standard atom-optics
delta-kicked rotor (AODKR), where we add spatially periodic dissipation or loss to each pulse. The system evolution is therefore non-unitary.\n\nWe first investigate the emergence of the survival resonances by exposing a cloud of laser-cooled Rubidium-85 atoms to standing-wave light pulses. The frequency of the light is tuned close to an open atomic transition. Scattering of the light from the standing wave leads the atoms to decay into a dark state that is far-off-resonance to both the standing-wave light and the subsequent detection light. Once the atoms go to the dark state, they are considered to be lost. The atom number is thereby {\\it not} a conserved quantity. Consequently, a meaningful dynamic observable is the survival probability of the atoms. Varying the pulse interval reveals a series of resonant peaks at integer multiples of half the Talbot time. These peaks are deemed survival resonances and are a matter-wave interferometric phenomenon. The appearance of the peaks can be conceptually understood through the matter-wave Talbot-Lau effect. For a complete understanding, we build a model to simulate the system which captures the dynamics well.\n\nIn addition to acting as an optical mask that modulates the wave functions' amplitude, the still present optical dipole force of the standing wave imprints a phase pattern to the atomic wave functions. This gives rise to a micro-lensing effect that increases the peak survival dramatically. Using such an effect can help to enhance the incisiveness of the resonances, which might find applications in precision measurements.\n\nThe width of survival resonance peaks narrows faster than expected from the Fourier-limit when the pulse number is changed. The standard AODKR displays a similar sub-Fourier behavior.\n\nThis thesis also demonstrates two applications of using survival resonances. The temporally pulsed spatially periodic dissipation is used for preparing well-defined initial conditions. Feeding back lost atoms gives a non-thermal atomic state that enhances subsequent survival resonance measurements. This can find its application in the state preparation in atom interferometry.\n\nTo show the feasibility of using survival resonances in an atom interferometer, we construct a proof-of-concept atomic gravimeter. With a vertically arranged standing-wave light beam, we perform an interferometric measurement of the gravitational acceleration
g utilizing the survival resonances. Gravity removes the survival resonances, but they re-emerge when the standing wave co-moves with the free-falling atomic cloud. To study the performance of this technique and find a good parameter combination, we carry out a series of simulations and experiments. We measure
g with a precision of 5 ppm using a drop distance of less than 1 mm. The sensitivity improves with the square of the drop time, which indicates we can reach a precision of the
mu-Gal regime with a drop distance of 10 cm. The simple implementation makes this technique an attractive candidate for a low cost and compact atomic gravimeter.
We present measurements on Earth's gravitational acceleration (g) using an in-house developed cold atom gravimeter (CAG) in an atomic fountain geometry. In the setup, the laser cooled
87Rb atoms are launched vertically up in the fountain geometry and Doppler sensitive two-photon Raman pulse atom interferometry is applied to detect the gravitational acceleration experienced by the atoms. Using our gravimeter setup, we have measured the local value of 'g' in our laboratory with sensitivity of 621
μGal for integration time of 1350 s.
Atoms from an otherwise unconfined 87Rb condensate are shown to be suspended against gravity using repeated reflections from a pulsed optical standing wave. Reflection efficiency was optimized using a triple-pulse sequence that, theoretically, provides accuracies better than 99.9%. Experimentally, up to 100 reflections are observed, leading to dynamical suspension for over 100 ms. The velocity sensitivity of the reflections can be used to determine the local gravitational acceleration. Further, a gravitationally sensitive atom interferometer was implemented using the suspended atoms, with packet coherence maintained for a similar time. These techniques could be useful for the precise measurement of gravity when it is impractical to allow atoms to fall freely over a large distance.
We investigate laser-cooled atoms periodically driven by pulsed standing waves of light tuned close to an open atomic transition. This nonunitary system displays survival resonances for certain driving frequencies. The survival resonances emerge as a result of the matter-wave Talbot-Lau effect, similar to the Talbot effect causing quantum resonances in the atom optics $\ensuremath{\delta}$-kicked rotor. Since the Talbot-Lau effect occurs for incoherent waves, the survival resonances can be observed using thermal atoms. A microlensing effect can enhance the height and incisiveness of the resonances. This may find applications in precision measurements.
We present a scheme of a compact atomic gravimeter based on atom interferometry. Atoms are maintained against gravity using a sequence of coherent accelerations performed by the Bloch oscillations technique. We demonstrate a sensitivity of $4.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ with an integration time of 4 min. Combining this method with an atomic elevator allows us to measure the local gravity at different positions in the vacuum chamber. This method can be of relevance to improve the measurement of the Newtonian gravitational constant
G.
This paper introduces an atomic gravimeter under development at KRISS for precise measurement of gravitational acceleration. The gravimeter based on atom interferometer uses two counter-propagating Raman lasers of π/2-π-π/2 pulse sequence and laser cooled87Rb atoms in free fall. Atomic interference fringes caused by Raman lasers were observed at various time intervals between the three Raman pulses. The frequency sweep rate α which compensates Doppler shift due to gravitational acceleration g was obtained from the interference fringes. In the presentation, the current status and recent results of the KRISS atomic gravimeter will be discussed.