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Register a new userInteracting quantum mixtures for precision atom interferometry
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Authors
Robin Corgier
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We present a source engineering concept for a binary quantum mixture suitable as input for differential, precision atom interferometry with drift times of several seconds. To solve the non-linear dynamics of the mixture, we develop a set of scaling approach equations and verify their validity contrasting it to the one of a system of coupled Gross-Pitaevskii equations. This scaling approach is a generalization of the standard approach commonly used for single species. Its validity range is discussed with respect to intra- and inter-species interaction regimes. We propose a multi-stage, non-linear atomic lens sequence to simultaneously create dual ensembles with ultra-slow kinetic expansion energies, below 15 pK. Our scheme has the advantage of mitigating wave front aberrations, a leading systematic effect in precision atom interferometry.
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We propose a tractor atom interferometer (TAI) based on three-dimensional (3D) confinement and transport of split atomic wavefunction components in potential wells that follow programmed paths. The paths are programmed to split and recombine atomic wavefunctions at well-defined space-time points, guaranteeing closure of the interferometer. Uninterrupted 3D confinement of the interfering wavefunction components in the tractor wells eliminates coherence loss due to wavepacket dispersion. Using Crank-Nicolson simulation of the time-dependent Schrodinger equation, we compute the quantum evolution of scalar and spinor wavefunctions in several TAI sample scenarios. The interferometric phases extracted from the wavefunctions allow us to quantify gravimeter sensitivity, for the TAI scenarios studied. We show that spinor-TAI supports matter-wave beam splitters that are more robust against non-adiabatic effects than their scalar-TAI counterparts. We confirm the validity of semiclassical path-integral phases taken along the programmed paths of the TAI. Aspects for future experimental realizations of TAI are discussed.
We demonstrate matterwave interference in a warm vapor of rubidium atoms. Established approaches to light pulse atom interferometry rely on laser cooling to concentrate a large ensemble of atoms into a velocity class resonant with the atom optical light pulse. In our experiment, we show that clear interference signals may be obtained without laser cooling. This effect relies on the Doppler selectivity of the atom interferometer resonance. This interferometer may be configured to measure accelerations, and we demonstrate that multiple interferometers may be operated simultaneously by addressing multiple velocity classes.
Atom interferometers offer excellent sensitivity to gravitational and inertial signals but have limited dynamic range. We introduce a scheme that improves on this trade-off by a factor of 50 using composite fringes, obtained from sets of measurements with slightly varying interrogation times. We analyze analytically the performance gain in this approach and the trade-offs it entails between sensitivity, dynamic range, and temporal bandwidth, and we experimentally validate the analysis over a wide range of parameters. By combining composite-fringe measurements with a particle-filter estimation protocol, we demonstrate continuous tracking of a rapidly varying signal over a span two orders of magnitude larger than the dynamic range of a traditional atom interferometer.
We present a modular rack-mounted laser system for the cooling and manipulation of neutral rubidium atoms which has been developed for a portable gravimeter based on atom interferometry that will be capable of performing high precision gravity measurements directly at sites of geophysical interest. This laser system is constructed in a compact and mobile design so that it can be transported to different locations, yet it still offers improvements over many conventional laboratory-based laser systems. Our system is contained in a standard 19 rack and emits light at five different frequencies simultaneously on up to 12 fibre ports at a total output power of 800 mW. These frequencies can be changed and switched between ports in less than a microsecond. The setup includes two phase-locked diode lasers with a phase noise spectral density of less than 1 mu rad/sqrt(Hz) in the frequency range in which our gravimeter is most sensitive to noise. We characterize this laser system and evaluate the performance limits it imposes on an interferometer.
We propose a set of experiments in which Ramsey-fringe techniques are tailored to probe transitions originating and terminating on the same ground state level. When pulses of resonant radiation, separated by a time delay $% T, $ interact with atoms, it is possible to produce Ramsey fringes having widths of order 1/T. If each pulse contains two counterpropagating travelling wave modes, the atomic wave function is split into two or more components having different center-of-mass momenta. Matter-wave interference of these components leads to atomic gratings, which have been observed in both spatially separated fields and time separated fields. Time-dependent signals can be transformed into frequency dependent signals, leading to ground state Ramsey fringes (GSRF). The signals can be used to probe many problems of fundamental importance: a precise measurement of the earth gravitational acceleration $g$ and residual gravity in a microgravity environment with an accuracy $6 10^{-9}g;$ the rotation rate measurement with an accuracy of 6 10^{-3} deg/h; the recoil frequency measurement. Since only transitions originating and terminating on the same ground state are involved, frequency measurements can be carried out using lasers phase-locked by quartz oscillators having relatively low frequency. Our technique may allow one to increase the precision by a factor of 100 (the rf- to quartz oscillator frequencies ratio) over previous experiments based on Raman-Ramsey fringes or reduce on the same factor requirements for frequency stabilization.
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