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We explore the potential of direct spectroscopy of ultranarrow optical transitions of atoms localized in an optical cavity. In contrast to stabilization against a reference cavity, which is the approach currently used for the most highly stabilized lasers, stabilization against an atomic transition does not suffer from Brownian thermal noise. Spectroscopy of ultranarrow optical transitions in a cavity operates in a very highly saturated regime in which nonlinear effects such as bistability play an important role. From the universal behavior of the Jaynes-Cummings model with dissipation, we derive the fundamental limits for laser stabilization using direct spectroscopy of ultranarrow atomic lines. We find that, with current lattice clock experiments, laser linewidths of about 1 mHz can be achieved in principle, and the ultimate limitations of this technique are at the 1 µHz level. [ABSTRACT FROM AUTHOR]

Optical Feshbach resonances (OFRs) have generated significant experimental interest in recent years. These resonances are promising for many-body physics experiments, yet the practical application of OFRs has been limited. The theory of OFRs has been based on an approximate model that fails in important detuning regimes, and the incomplete theoretical understanding of this effect has hindered OFR experiments. We present the most complete theoretical treatment of OFRs to date, demonstrating important characteristics that must be considered in OFR experiments and comparing OFRs to the well-studied case of magnetic Feshbach resonances. We also present a comprehensive treatment of the approximate OFR model, including a study of the range of validity for this model. Finally, we derive experimentally useful expressions that can be applied to real experimental data to extract important information about the resonance structure of colliding atoms. [ABSTRACT FROM AUTHOR]

We consider the phase stability of a local oscillator (or laser) locked to a cavity-QED system composed of atoms with an ultranarrow optical transition. The atoms are cooled to milli-Kelvin temperatures and then released into the optical cavity. Although the atomic motion introduces Doppler broadening, the standing-wave nature of the cavity causes saturated absorption features to appear, which are much narrower than the Doppler width. These features can be used to achieve an extremely high degree of phase stabilization, competitive with the current state of the art. Furthermore, the inhomogeneity introduced by finite atomic velocities can cause optical bistability to disappear, resulting in no regions of dynamic instability and thus enabling a new regime accessible to experiments where optimum stabilization may be achieved. [ABSTRACT FROM AUTHOR]

Based on spectroscopy of the (3s3p)3P0-(3s3d)³D1 Mg i transitions for the stable isotopes 24Mg(I = 0), 25Mg(I = 5/2), and 26Mg(I = 0) we report measurements of the 25Mg(3s3d)³DJ hyperfine coefficients A(³D1) = 141±7,A(³D2) = -59±6, and A(3D3) = -97±3MHz. We find the hyperfine coefficients in agreement with state-of-the-art theoretical predictions presented here giving A(³D1) = 143.3±1.4,A(³D2) = -48.3±0.5, and A(³D3) = -96±1MHz. We also report measurements of the isotope shifts for the investigated transitions Δ24-25 = 6±9 and Δ24-26 = 59.7±0.5MHz, significantly reducing the uncertainty compared to previous measurements. [ABSTRACT FROM AUTHOR]

Hybrid systems of cold atoms and optical cavities are promising systems for increasing the stability of laser oscillators used in quantum metrology and atomic clocks. In this paper we map out the atom-cavity dynamics in such a system and demonstrate limitations as well as robustness of the approach. We investigate the phase response of an ensemble of cold 88Sr atoms inside an optical cavity for use as an error signal in laser frequency stabilization. With this system we realize a regime where the high atomic phase shift limits the dynamical locking range. The limitation is caused by the cavity transfer function relating input field to output field. The cavity dynamics is shown to have only little influence on the prospects for laser stabilization, making the system robust towards cavity fluctuations and ideal for the improvement of future narrow linewidth lasers. [ABSTRACT FROM AUTHOR]

A correction to the article "Laser stabilization using saturated absorption in a cavity-QED system" is presented.