38 research outputs found
Observation of dressed intra-cavity dark states
Cavity electromagnetically induced transparency in a coherently prepared
cavity-atom system is manifested as a narrow transmission peak of a weak probe
laser coupled into the cavity mode. We show that with a resonant pump laser
coupling the cavity-confined four-level atoms from free space, the narrow
transmission peak of the cavity EIT is split into two peaks. The two peaks
represent the dressed intra-cavity dark states and have a frequency separation
approximately equal to the Rabi frequency of the free-space pump laser. We
observed experimentally the dressed intra-cavity dark states in cold Rb atoms
confined in a cavity and the experimental results agree with theoretical
calculations based on a semiclassical analysis.Comment: 10 pages, 6 figure
Coherent manipulation of quantum states in a coupled cavity-atom system
We study atomic coherence and interference in four-level atoms confined in an optical cavity and explores the interplay between cavity QED and electromagnetically induced transparency (EIT). The destructive interference can be induced in the coupled cavityatom system with a free-space control laser tuned to the normal mode resonance and leads to suppression of the normal mode excitation. Then by adding a pump laser coupled to the four-level atoms from free space, the control-laser induced destructive interference can be reversed and the normal mode excitation is restored. When the free-space control laser is tuned to the atomic resonance and forms a Λ-type EIT configuration with the cavity-atom system, EIT is manifested as a narrow transmission peak of a weak probe laser coupled into the cavity mode. With the free-space pump laser driving the cavity-confined atoms in a four-level configuration, the narrow transmission peak of the cavity EIT can be split into two peaks and the dressed intra-cavity dark states are created analogous to the dressed states in free space. We report experimental studies of such coherently coupled cavityatom system realized with cold Rb atoms confined in an optical cavity and discuss possible applications in quantum nonlinear optics and quantum information science
Vacuum Rabi splitting and intracavity dark state in a cavity-atoms system
We report experimental measurements of the transmission spectrum of an
optical cavity coupled with cold Rb atoms. We observe the multi-atom vacuum
Rabi splitting of a composite cavity and atom system. When a coupling field is
applied to the atoms and induces the resonant two-photon Raman transition with
the cavity field in a Lamda-type three-level system, we observe a cavity
transmission spectrum with two vacuum Rabi sidebands and a central peak
representing the intracavity dark state. The central peak linewidth is
significantly narrowed by the dark-state resonance and its position is
insensitive to the frequency change of the empty cavity.Comment: 11 pages, 4 figure
Batch-based Model Registration for Fast 3D Sherd Reconstruction
3D reconstruction techniques have widely been used for digital documentation
of archaeological fragments. However, efficient digital capture of fragments
remains as a challenge. In this work, we aim to develop a portable,
high-throughput, and accurate reconstruction system for efficient digitization
of fragments excavated in archaeological sites. To realize high-throughput
digitization of large numbers of objects, an effective strategy is to perform
scanning and reconstruction in batches. However, effective batch-based scanning
and reconstruction face two key challenges: 1) how to correlate partial scans
of the same object from multiple batch scans, and 2) how to register and
reconstruct complete models from partial scans that exhibit only small
overlaps. To tackle these two challenges, we develop a new batch-based matching
algorithm that pairs the front and back sides of the fragments, and a new
Bilateral Boundary ICP algorithm that can register partial scans sharing very
narrow overlapping regions. Extensive validation in labs and testing in
excavation sites demonstrate that these designs enable efficient batch-based
scanning for fragments. We show that such a batch-based scanning and
reconstruction pipeline can have immediate applications on digitizing sherds in
archaeological excavations. Our project page:
https://jiepengwang.github.io/FIRES/.Comment: Project page: https://jiepengwang.github.io/FIRES
Nonlinear optical effects manifested by electromagnetic induced transparency in cold atoms
This dissertation reports experimental studies of nonlinear optical effects manifested by electromagnetically induced transparency (EIT) in cold Rb atoms. The cold Rb atoms are confined in a magneto-optic trap (MOT) obtained with the standard laser cooling and trapping technique. Because of the near zero Doppler shift and a high phase density, the cold Rb sample is well suited for studies of atomic coherence and interference and related applications, and the experiments can be compared quantitatively with theoretical calculations. It is shown that with EIT induced in the multi-level Rb system by laser fields, the linear absorption is suppressed and the nonlinear susceptibility is enhanced, which enables studies of nonlinear optics in the cold atoms with slow photons and at low light intensities. Three independent experiments are described and the experimental results are presented. First, an experimental method that can produce simultaneously co-propagating slow and fast light pulses is discussed and the experimental demonstration is reported. Second, it is shown that in a three-level Rb system coupled by multi-color laser fields, the multi-channel two-photon Raman transitions can be manipulated by the relative phase and frequency of a control laser field. Third, a scheme for all-optical switching near single photon levels is developed. The scheme is based on the phase-dependent multi-photon interference in a coherently coupled four-level system. The phase dependent multi-photon interference is observed and switching of a single light pulse by a control pulse containing ∼20 photons is demonstrated. These experimental studies reveal new phenomena manifested by quantum coherence and interference in cold atoms, contribute to the advancement of fundamental quantum optics and nonlinear optics at ultra-low light intensities, and may lead to the development of new techniques to control quantum states of atoms and photons, which will be useful for applications in quantum measurements and quantum photonic devices