The first observation of Pr^{+} ions stored in a Paul trap is reported. Initially the ions were observed by the electronic detection method, and further the laser induced fluorescence, following resonance absorption at a certain optical transition in Pr^{+} ion, which is excited from the ground state, was recorded. Moreover, fluorescence signal following the excitation from a low-lying metastable state could be detected. The Paul trap system and some other parts of the experimental setup were constructed within the frame of this work and thus are briefly described in the present contribution.
A variable length linear trap operating between 20-1000 Hz under standard temperature and pressure conditions is reported. We simulated and observed various kinds of stable patterns: linear strings, planar zig-zag and volume structures. The interparticle distances depend on the trapped particle number and trap length. Our setup allows trapped microparticle diagnosis by various methods.
We describe recent experimental and theoretical results which show that the light pressure force for an atom with more than two levels, in a field with more than one frequency or which is studied in more than one dimension can display striking new features. The importance of these results lies in the fact that they cannot be explained in terms of a two-level, a monochromatic or a one-dimensional theory.
The techniques of laser cooling have now become sufficiently developed that the focus has shifted toward interesting applications such as the quantum domain of atomic motion. This topic is characterized by the failure of the classical description in which atoms move as point particles whose trajectories can be known: instead, atomic motion must be described as the optics of de Broglie waves. For example, when the de Broglie wavelength λ_{dB} exceeds λ_{optical}, then a classical description is insufficient (Bose condensation is done in the dark, and the quantum condition becomes λ_{dB} > nearest neighbor distance). One of the most fascinating topics of quantized atomic motion in a laser field derives from optical dark states that can even occur in the simplest (two-level) atoms, where there are no magnetic sublevels and the polarization is irrelevant. In spite of the simplicity of this two-level atom case however, the more interesting cases occur in multilevel atoms where the internal magnetic states and external quantum states of atomic motion become truly entangled. Schrödinger called such states "the heart of quantum mechanics" because they led to puzzles such as his famous "cat" and the EPR paradox.
In many fields of atomic and molecular physics we need to combine the center-of-mass motion with internal degrees of freedom. In this work, the classical motion in phase space is separated from the quantum processes by a multiple-time-scale approach. The expansion parameter is proportional to Planck's constant. The theory is given and illustrated by examples: the semiclassical description of a particle without internal states, the extraction of a classical trajectory and the derivation of the light-induced force.
The problem of resonant motion induced by the dipole component of the antisymmetric potential function in a radiofrequency Paul trap is investigated here. We show that, at low-level additional rf-voltage, the line-shape and the increasing rate of its amplitude, for the ion-excitation phenomenon, can be derived from the dipole approximation of the antisymmetric term in the potential energy. This approximation does not take into account the observed line-shift.
As research in quantum optics has advanced, so too has our ability to precisely tailor the quantum state of a system. Indeed, techniques for quantum state preparation have become sufficiently advanced that an entire subfield has appeared which has been given the name "quantum control". Parallel to these advances have been other striking developments in quantum optics, in particular, laser cooling and trapping of neutral atoms. In this paper we describe some of the recent advancements in laser cooling, particularly in our laboratories, and point out that laser cooling and trapping is also realizing an important form of quantum control. In laser cooling, instead of exercising control over the internal quantum state of an atom or molecule or a laser field, we are instead controlling a complementary set of degrees of freedom: those of the external coordinates of the atom.
We have designed a gravitational cavity for ultra-cold atoms using an atomic mirror made from an evanescent laser wave. By a temporal variation of the evanescent wave intensity, we have realized various atom optics components such as temporal slits and phase modulators. We have also designed an atom interferometer using this cavity which proves that the coherence of the de Broglie waves can be preserved during the bounce of the atoms on the mirror. Finally we show that an efficient cooling of the atoms inside the cavity can be achieved using a Sisyphus process during the bounce.
Pump-probe spectroscopy of cold, trapped atoms is discussed with particular attention to mechanisms specific for cold atoms and potential diagnostics applications. The discussion is illustrated with experimental results obtained with ^{85}Rb atoms trapped in a magneto-optical trap. Most important applications are non-destructive, real-time velocimetry (thermometry) and analysis of optical lattice dynamics.
This paper presents fundamental principles, characteristics, and limitations of various experimental methods of cooling and trapping of neutral atoms by laser light and magnetic fields. In addition to surveying the experimental techniques, basic properties of quantum degenerate gases are discussed with particular emphasis on the Bose-Einstein condensate. We also present main parameters and expected characteristics of the first Polish Bose-Einstein condensate apparatus built in the National Laboratory of Atomic, Molecular, and Optical Physics in Toruń, Poland.
We report on our studies of atoms contained in a magneto-optical trap using the nonlinear spectroscopy methods. Absorption and four-wave mixing signals are recorded for the probe frequency near the cooling transition frequency and the two methods are compared. The differences in the signal structure and their sensitivity on external conditions are discussed. It is revealed that central feature of these spectra consists of several contributions of different origin.
We review the current status of the U.S. Primary Frequency Standard, NIST-F1. NIST-F1 is a laser-cooled cesium fountain based frequency standard with an inaccuracy of less thanδ f/f<5×10^{-16}; limited mainly by the radiation field in the room-temperature fountain (blackbody shift). NIST-F1 is one of the best cesium fountains currently contributing to international atomic time, but has reached a point that it is impractical to improve its accuracy substantially. Therefore we are building a new fountain, imaginatively named NIST-F2, with a cryogenic (77 K) Ramsey interrogation zone that lowers the blackbody shift by several orders of magnitude. NIST-F2 is currently undergoing final assembly, and we will discuss our planned (hoped for) performance, which includes frequency inaccuracy ofδ f/f<1×10^{-16}.
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