While for the most part quantum statistical processes in quantum optics are investigated in a weak coupling regime, it has recently become possible to realize experimentally optical systems for which the internal coupling coefficient g is comparable to the external dissipative rates. Within this context the subject of our investigation is the quantum dynamical processes for a collection of N two-state atoms strongly coupled to a single mode of a high finesse optical cavity, Our particular experiment consists of a small collection of Cesium atoms (6S1/2, F = 4 → 6P3/2, F = 5 transition at 852nm) interacting with the TEM00 mode of a spherical mirror cavity. The critical technical advance for this work is the attainment of extremely low loss mirrors for high finesse (103 – 106) and hence long photon lifetime even in a small cavity.[1]
While for the most part quantum statistical processes in quantum optics are investigated in a weak coupling regime, it has recently become possible to realize experimentally optical systems for which the internal coupling coefficient g is comparable to the external dissipative rates. Within this context the subject of our investigation is the quantum dynamical processes for a collection of N two-state atoms strongly coupled to a single mode of a high finesse optical cavity, Our particular experiment consists of a small collection of Cesium atoms (6S1/2, F = 4 → 6P3/2, F = 5 transition at 852nm) interacting with the TEM00 mode of a spherical mirror cavity. The critical technical advance for this work is the attainment of extremely low loss mirrors for high finesse (103 – 106) and hence long photon lifetime even in a small cavity.[1]
While for the most part quantum statistical processes in quantum optics are investigated in a weak-coupling regime, it has recently become possible to realize experimentally systems for which the internal coupling coefficient g is comparable to the external dissipative rates. Within this context the subject of our investigation is the quantum dynamical processes for a collection of N two-state atoms strongly coupled to a single mode of a high finesse optical cavity. Our particular system consists of a collection of N~20 Cesium atoms (6S 1/2, f = 4– > 6P 3/2, f = 5 transition at 852 nm) interacting with the TEMoo mode of a spherical mirror cavity of finesse 4 × 104. Of principal importance are the single atom cooperativity parameter C1 = g 2/κγ and the saturation photon number no = g2/8γ 2, where (κ,γ) are the cavity and atomic decay rates. For our system, c1~1 and n0~0.5. In measurements of the joint probability of photoelectric detection we observe photon antibunching and sub-Poissonian photon statistics.1,2 An interpretation of our results in terms of quantum state reduction and interference in a dissipative dynamical setting is presented.2 We emphasize the decisive role played by the quantum fluctuations of a single atom (c1~1), which can result in a field of large variance even in the presence of N>1 atoms.
Of fundamental importance in quantum optics has been the investigation of the radiative coupling of a collection of atoms to the field of a resonant cavity1. Within this context we are conducting a research program to investigate the interaction of optically prepared two-state atoms with the fields of high finesse optical cavities. With regard to our specific observations, we have employed a sodium atomic beam apparatus to make direct spectroscopic measurements of the normal-mode splitting for the coupled oscillator system formed by the collective atomic polarization of N two-state atoms and a single mode of a resonator of finesse of approximately 2x10⁴. At the transition wavelength of 589 nm (³, S_(1/2), F = 2, m_F = 2→3 P_(3/2), m_F = 3 and for one of our spherical mirror standing-wave cavities, the relevant parameters for the system are as follows: transverse atomic decay rate γ_⊥ = 2πX5X10⁶/S, cavity damping rate K/γ⊥= 0.18, and single-atom coupling coefficient g/γ_⊥ = 0.2.
For the most part, quantum statistical processes in quantum optics are investigated in a weak-coupling regime, but it has become possible recently to realize experimentally optical systems for which the internal coupling coefficient g is comparable to the external dissipative rates. Within, this context, the subject of our investigation is the quantum dynamical processes for a small collection of N two-state atoms strongly coupled to a single mode of a high-finesse optical cavity. For this system, we record input-output characteristics for steady-state operation with 3 ⪝ N ⪝ 65 intracavity atoms and observe optical bistability for N⪞15 atoms.1
Investigations of the radiative processes for the composite system of N two-state atoms coupled to the field of a high finesse optical cavity are reported. In an experiment employing an atomic beam of optically prepared sodium atoms (3S1/2, F = 2, mF = 2 → 3P3/2, F = 3, mF = 3 transition at 589 nm), we make direct spectroscopic measurements of the normal mode splitting for the coupled oscillator system of atoms and cavity field over a 20 ≤ N ≤ 600 range. Linewidth reduction below the atomic free-space width is observed and results from dynamic linewidth averaging due to the strong coherent interaction of atoms and cavity. The dependence of the normalmode structure on atom-cavity detuning is explored, and the decoupling of the system with detuning is described. A second experimental program employs a cesium atomic beam (6S1/2, F = 4, mF = 4 → 6P3/2, F = 5, mF = 5 transition at 852 nm), for which the single-atom coupling coefficient can be made larger than the free-space atomic and cavity damping rates. Our initial efforts are directed both toward the investigation of the spectroscopic properties of this system and toward the observation of photon antibunching for the field transmitted from the cavity. More generally our measurements of intensity correlations can be applied to the problem of continuous quantum measurement for a dissipative system.
Strong coupling of single cesium atoms with a high-finesse optical micro-cavity (the finesse of our Fabry-Perot-type micro-cavity is F = 3.3 x 105 and the cavity length is lc = 86 μm) has been realized for the both cases of TEM00 and TEM10 cavity modes in our experiments. The typical parameters are (g00, κ, Υ) = 2π x (23.9, 2.6, 2.6) MHz and (g10, κ, Υ) = 2π x (20.5, 2.6, 2.6) MHz for these two cases, respectively. Obviously our system reaches the strong coupling regime. The first application is to adopt strong coupling of free-fall individual atoms with the TEM00 cavity mode for determining the effective temperature of laser-cooled atoms prepared in a magneto-optical trap located just above the micro-cavity. The second application is to employ strong coupling of free-fall individual atoms with the tilted TEM10 cavity mode, in stead of TEM00 mode, for more precisely tracking the trajectories of atoms passing through the cavity mode.
Cavity quantum electrodynamics (cavity QED) describes electromagnetic fields in a confined space and the radiative properties of atoms in such fields. The simplest example of such system is a single atom interacting with one mode of a high-finesse resonator. Besides observation and exploration of fundamental quantum mechanical effects, this system bears a high potential for applications quantum information science such as, e.g., quantum logic gates, quantum communication and quantum teleportation. In this thesis I present an experiment on the deterministic coupling of a single neutral atom to the mode of a high-finesse optical resonator. In Chapter 1 I describe our basic techniques for trapping and observing single cesium atoms. As a source of single atoms we use a high-gradient magneto-optical trap, which captures the atoms from background gas in a vacuum chamber and cools them down to millikelvin temperatures. The atoms are then transferred without loss into a standing-wave dipole trap, which provides a conservative potential required for experiments on atomic coherence such as quantum information processing and metrology on trapped atoms. Moreover, shifting the standing-wave pattern allows us to deterministically transport the atoms (Chapter 2). In combination with non-destructive fluorescence imaging of individual trapped atoms, this enables us to control their position with submicrometer precision over several millimeters along the dipole trap. The cavity QED system can distinctly display quantum behaviour in the so-called strong coupling regime, i.e., when the coherent atom-cavity coupling rate dominates dissipation in the system. This sets the main requirements on the resonator's properties: small mode volume and high finesse. Chapter 3 is devoted to the manufacturing, assembling, and testing of an ultra-high finesse optical Fabry-Perot resonator, stabilized to the atomic transition. In Chapter 4 I present the transportation of single atoms into the cavity and their coupling to the cavity mode. The strong coupling manifests itself in a strong reduction of the cavity transmission probed by a weak external laser. The atoms remain trapped and coupled to the cavity mode for several seconds until we move them out of the cavity for final analysis of their number and position.