Frank A. Narducci

Evidence of sympathetic cooling of Na+ ions by a Na magneto-optical trap in a hybrid trap

A hybrid ion-neutral trap provides an ideal system to study collisional dynamics between ions and neutrals. This system provides a general cooling method that can be applied to optically inaccessible species and can also potentially cool internal degrees of freedom. The long range polarization potentials (

Phase dynamics and interference in EIT

V\propto-\alpha/r^4

A proposal for a gradient magnetometer atom interferometer

) between ions and neutrals result in large scattering cross sections at cold temperatures, making the hybrid trap a favorable system for efficient sympathetic cooling of ions by collisions with neutral atoms. We present experimental evidence of sympathetic cooling in a hybrid trap of \ce{Na+} ions, which are closed shell and therefore do not have a laser induced atomic transition, by equal mass cold Na atoms in a magneto-optical trap (MOT).

Ion-neutral-atom sympathetic cooling in a hybrid linear rf Paul and magneto-optical trap

In this paper, we investigate various aspects of electro-magnetically induced transparency (EIT) that are associated with quantum interference. In the first half of this paper, we investigate two cascade schemes and demonstrate two possible absorption pathways in one, which leads to interference, and only one pathway in the other scheme, which does not exhibit EIT. In the second part of this paper, we demonstrate how EIT can be changed into enhanced absorption by changing the phase of either the coupling or probe fields.

Controlling Raman resonances with magnetic fields

We propose the utilization of atom interferometry techniques for the measurement of magnetic fields in noisy environments. We find that the interferometer we propose is insensitive (to first order) to the magnetic field but is sensitive to the field gradient. We propose a technique by which a superposition of magnetically sensitive states (a beam splitter) can be achieved. We experimentally demonstrate our techniques to null the magnetic field at the location of a cold atom cloud and how we can probe the population of magnetic sublevels.

Resonances and excitation pathways in four-level N-scheme atomic systems

Long range polarization forces between ions and neutral atoms result in large elastic scattering cross sections, e.g., 10^6 a.u. for Na+ on Na or Ca+ on Na at cold and ultracold temperatures. This suggests that a hybrid ion-neutral trap should offer a general means for significant sympathetic cooling of atomic or molecular ions. We present SIMION 7.0 simulation results concerning the advantages and limitations of sympathetic cooling within a hybrid trap apparatus, consisting of a linear rf Paul trap concentric with a Na magneto-optical trap (MOT). This paper explores the impact of various heating mechanisms on the hybrid system and how parameters related to the MOT, Paul trap, number of ions, and ion species affect the efficiency of the sympathetic cooling.

Four-level ‘N-scheme’ in bare and quasi-dressed states pictures

We utilize the tools already presented in a previous publication [DeSavage, S.A; Gordon, K.H; Clifton, E.M.; Davis, J.P.; Narducci, F.A. J. Mod. Opt. 2011, 58 (21), 2028--2035] to theoretically and experimentally investigate in detail Raman transitions in a sample of laser cooled 85Rb. Using cross-linearly polarized Raman fields, we find that, for an arbitrarily oriented magnetic field, the Raman spectrum consists of up to eleven peaks. However, by judicious choice of magnetic field direction, the spectrum can be reduced to a five peaked spectrum (transverse magnetic field) or a six peaked spectrum (longitudinal magnetic field). We present cases in which the full spectrum can not be thought of as the incoherent sum of the five and six peaked spectra.

Dynamic control of EIT by changing optical phase

In this work, we theoretically study the absorption and dispersion coefficients of a probe field in four-level N-scheme atomic systems driven by two additional fields. We separate the steady-state solution of the appropriate density matrix element into the sum of three resonances. The effect of each resonance on the overall absorption and dispersion experienced by the probe is studied as a function of the strengths of the two other fields. In the limit of low saturation, we reveal the physics of these resonances and associate them with atomic excitation pathways, which we explicitly explain in the bare-states picture.

Raman resonances in arbitrary magnetic fields

In this work, we consider a four-level ‘N-scheme’ (three radiation fields coupling four atomic levels) that has previously been shown to feature different group velocity regimes (sub-luminal, super-luminal, and negative) controlled by the strength of the third interacting field, which is referred to as the control field. Another interesting aspect of the N-scheme is the ‘appearance’ and ‘disappearance’ of an electromagnetically induced transparency (EIT) window at resonance. In this paper, based on a study in the bare states picture, we point out differences and similarities between two settings (different strengths of the acting fields) of this four-level N-scheme. Conclusions are drawn based on a work in a simplified quasi-dressed states picture. We find that the four-level N-scheme under study can be approached as either a one or two three-level lambda-like system(s) that display the same physics regardless of the relative strength between the two fields that form the EIT portion of the system.

Quantum optic techniques for diagnostics of a gradient magnetometer atom interferometer

We have studied phase dynamics in EIT in a dense rubidium vapor. We have observed a very fast growth of the absorption when the phase of the optical field was abruptly changed, followed by a slow return to the steady state absorption. Then the transmission was slowly restored to stationary magnitude. The recovery time is on the order of the transit time of the atom flying through the laser beam and decreases with increasing optical power. The fast variation of the transparency is proportional to the phase deviation. The obtained result can be used for the fast control of EIT, for example, in an optical switch.