Motivated by recent results using shaken optical lattices to perform atom interferometry, we explore the splitting of an atom cloud trapped in a phase-modulated (‘shaken’) optical lattice. Using a simple analytic model we are able to show that we can obtain the simplest case of ±2ℏ k L splitting via single-frequency shaking. This is confirmed both via simulation and experiment. Furthermore, we are able to split with a relative phase θ between the two split arms of 0 or π depending on our shaking frequency. Addressing higher-order splitting, we determine that ±6ℏ k L splitting is sufficient to be able to accelerate the atoms in counterpropagating lattices. Finally, we show that we can use a genetic algorithm to optimize ±4ℏ k L and ±6ℏ k L splitting to within ≈0.1% by restricting our optimization to the resonance frequencies corresponding to single- and two-photon transitions between Bloch bands. As a proof-of-principle, an experimental demonstration of simplified optimization of 4ℏ k L splitting is presented.
Motivated by recent results using shaken optical lattices to perform atom interferometry, we explore the splitting of an atom cloud trapped in a phase-modulated (‘shaken’) optical lattice. Using a simple analytic model we are able to show that we can obtain the simplest case of ±2ℏ k L splitting via single-frequency shaking. This is confirmed both via simulation and experiment. Furthermore, we are able to split with a relative phase θ between the two split arms of 0 or π depending on our shaking frequency. Addressing higher-order splitting, we determine that ±6ℏ k L splitting is sufficient to be able to accelerate the atoms in counterpropagating lattices. Finally, we show that we can use a genetic algorithm to optimize ±4ℏ k L and ±6ℏ k L splitting to within ≈0.1% by restricting our optimization to the resonance frequencies corresponding to single- and two-photon transitions between Bloch bands. As a proof-of-principle, an experimental demonstration of simplified optimization of 4ℏ k L splitting is presented.
We introduce shaken lattice interferometry with atoms trapped in a one-dimensional optical lattice. By phase modulating (shaking) the lattice, we control the momentum state of the atoms. Through a sequence of shaking functions, the atoms undergo an interferometer sequence of splitting, propagation, reflection, reverse propagation, and recombination. Each shaking function in the sequence is optimized with a genetic algorithm to achieve the desired momentum state transitions. As with conventional atom interferometers, the sensitivity of the shaken lattice interferometer increases with interrogation time. The shaken lattice interferometer may also be optimized to sense signals of interest while rejecting others, such as the measurement of an ac inertial signal in the presence of an unwanted dc signal.
We experimentally demonstrate a shaken-lattice interferometer. Atoms are trapped in the ground Bloch state of a red-detuned optical lattice. Using a closed-loop optimization protocol based on the dcrab algorithm, we phase-modulate (shake) the lattice to transform the atom momentum state. In this way, we implement an atom beam splitter and build five interferometers of varying interrogation times T_{I}. The sensitivity of shaken-lattice interferometry is shown to scale as T_{I}^{2}, consistent with simulation (2C. A. Weidner, H. Yu, R. Kosloff, and D. Z. Anderson, Phys. Rev. A 95, 043624 (2017).PLRAAN2469-992610.1103/PhysRevA.95.043624). Finally, we show that we can measure the sign of an applied signal and optimize the interferometer in the presence of a bias signal.
Since the first demonstrations in 1991, atom interferometry has been a burgeoning field of research. The work done in this field is motivated by the potential sensitivity improvements that atom-based devices can have over the current state-of-the-art light- and MEMS-based devices. This dissertation presents a new and unique approach to atom interferometry in that we perform the basic interferometric sequence of splitting, propagation, reflection, reverse-propagation, and recombination with atoms trapped in a phase-modulated (shaken) optical lattice. In both simulation and experiment we demonstrate a one-dimensional shaken lattice interferometer configured as an accelerometer. The interferometry sequence is developed through the use of learning and optimal control algorithms that allow us to implement the desired state-to-state transformations and perform the desired operations, e.g. splitting and recombination of the atoms trapped in the lattice. This device has a sensitivity that scales as the square of the interrogation time and an ability to distinguish both the magnitude and sign of an applied acceleration signal. Furthermore we show that we can tailor the transfer function of the interferometer to be sensitive to a signal of interest, e.g. an AC signal of a given frequency. Finally, we explore the analytics of shaken lattice interferometry and offer some suggestions as to the future of this new technology.
The creation of a 1D matter-wave interferometer can be achieved by utilizing ultracold atoms loaded into an optical lattice. By shaking the lattice via either phase or frequency modulation, the traditional steps of interferometry- effectively splitting, propagating, reflecting, again propagating and then recombining the atomic wavefunction- can be implemented, allowing for the sensing of inertial signals. This approach is interesting, since the atoms can be supported against external forces and perturbations, and the system can be completely reconfigurable on-the-fly for a new design goal. We report on experimental results in which atoms are cooled into a dipole trap and subsequently loaded into an optical lattice. Shaking protocols for obtaining interferometry steps are derived via machine learning and quantum optimal control methods. We report experimental progress in realizing a shaken lattice interferometer and its sensitivity to an applied acceleration signal along with the possibility of tailoring the signal to specific scenarios. Additionally, closed loop learning from the experiment to improve signal sensitivity is explored and demonstrated.
The creation of a matter-wave interferometer can be achieved by loading Bose-Einstein condensed atoms into an optical lattice. By shaking the lattice via either phase or frequency modulation, the traditional steps of interferometry; splitting, propagating, reflecting, again propagating and then recombining the atomic wavefunction, can be implemented, allowing for the sensing of broad range of inertial signals. This approach is interesting, since the atoms can be supported against external forces and perturbations, and the system can be completely reconfigurable on-the-fly for a new design goal. We report on theoretical and experimental results in which atoms are cooled to degeneracy in a dipole trap and subsequently loaded into a multidimensional optical lattice. Shaking protocols for obtaining interferometry steps are derived via machine-design approaches consisting of machine learning and quantum optimal control. Experimental confirmation of the designed operation of a two-dimensional vector accelerometer is shown and its performance to applied accelerations measured. Both the direction and magnitude of the applied signal is varied and validation of both scenarios presented.
We present a simple way to control the phase of an optical lattice by detecting the interference signal of two beams. The optical lattice is intentionally shaken by varying the relative phase of the beams. However, the lattice may also be shaken by unwanted variations of the relative optical path length, e.g., due to mirror vibrations. The purpose of the servo is to attenuate these unwanted variations while the intended shaking remains. We demonstrate that the servo changes the relative phase between beams and follows the intended shaking function with 99% accuracy. The bandwidth for the acceptable attenuation of unwanted shaking, -13 dB, is measured to 1.2 kHz to control the atomic Bloch state. The servo will be implemented to attenuate the unknown system vibrations for a shaken lattice and engineer the momentum state of atoms trapped in the lattice. This idea can also be applied to any time varying experiment.