(a) (b) (c) N cav P e g cav (2) Δ$_{c }$ [MHz] FIG. 5: Mean photon number N$_{cav}$ , second-order photon correlation function g (2) $_{cav}$, and atomic excited-state population P$_{e}$ as functions of the detuning Δ$_{c}$ of the probe field from the cavity resonance. The cavity is at exact resonance with the atom in free space, i.e. ω$_{c}$ = ω$_{0}$ . The distance from the atom to the fiber surface is r − a = 200 nm (solid lines), 100 nm (dashed lines), and 50 nm (dotted lines). The axial position z of the atom along the fiber corresponds to an antinode of the cavity standing-wave field. Other parameters are as for Fig. 3. the correlation function g (2) cav can become larger than 2, that is, the photon distribution of the guided cavity field can become broader than the Boltzmann distribution for thermal states. Such a broadening of the photon distribution is a consequence of the emission from the excited atom. According to Fig. 5, the effect of the atom on the guided cavity field depends on the FIG. 6: Same as Fig. 3 except for the detuning Δ$_{c}$ = 30 MHz. r - a  [nm] (a) (b) (c) N cav P e g cav (2) 17