Observation of Quantum Jumps in a Single Atom

Abstract

Dehmelt had proposed this optical double-resonance scheme (terming it electron shelving) as an amplification mechanism to detect a weak transition in singleatom spectroscopy. 5 This technique has been used for several years in high-resolution spectroscopic studies of samples of many laser-cooled ions, achieving quantum amplifications of 10 and higher. In 1981, electron-shelving amplification was used to perform optical-optical double resonance in a single, lasercooled, trapped ion. While the signal-to-noise ratio in that experiment was not sufficient to see quantum jumps directly, the fact that the atomic fluorescence would be bistable was noted. More recently, the statistics of quantum switching in a single atom have been theoretically treated in some detail first by Cook and Kimble7 and subsequently by several other authors. s '3 In this Letter we report the clear experimental demonstration of quantum jumps in a single laser-cooled '9sHg+ ion stored in a miniature radio-frequency trap.The basic idea for quantum switching and the associated statistics is illustrated with the three-level system shown in Fig. 1 is also admitted, then the atom will occasionally be driven into the metastable state and the fluorescence from the strong transition will abruptly disappear. The cessation of the scattering of many photons on the strong transition for one photon absorbed on the weak transition permits unit detection efficiency of the transition to the metastable state. 6' Some time later, the atom returns spontaneously or is driven out of the D state back to the ground state, which causes a sudden return of the fluorescence on the strong transition.

Speed of ion-trap quantum-information processors

“…Then, by monitoring fluorescence at 397 nm under laser excitation, we detect whether a transition to the non-fluorescing state D 5/2 occurred. The scheme allows one to discriminate between the internal states of the ion with an efficiency close to 100% [18][19][20]. In our experiment,the discrimination effiency is approximately 99.8%, limited by the lifetime of the metastable state [21].…”

“…Our calculations lead to quantitative statements of the precision of the operations, taking into account the complete Hamiltonian including all the vibrational states and the off-resonant coupling terms. These statements are given in equations (17), (18) for the Monroe et al "magic Lamb Dicke parameter" gate, and in equations (19), (20) for the Cirac-Zoller swap gate. If we set a limit of a fixed number of laser wavelengths for the spacing of the ions in a linear trap, then we arrive at a gate time per ion, for the swap gate, which depends only on the precision and the choice of ion and transition.…”

Monitoring the Decoherence of Mesoscopic Quantum Superpositions in a Cavity

“…In many modern experiments, an information is continuously extracted from the system's environment and its wave function follows a random trajectory exhibiting explicit quantum jumps [21,22,23]. The statistics of these jumps is reproduced by a Monte Carlo simulation involving an environment with as many states as the number of possible exclusive measurements outcomes.…”

An optical soliton pair among absorbing three-level atoms

“…The off-diagonal elements describe atomic coherences. The 10 -and ρ 20 -terms oscillate at the respective driving field frequency and the 21 oscillate with the frequency differences of the two light fields. So, we can define the slowly varying amplitudes of the off-diagonal density matrix elementsρ 10 ,ρ 20 , andρ 21 through the relations…”

“…Using this theoretical approximation, interesting phenomena have been predicted and then observed, such as the resonance fluorescence spectrum [3,4], photon antibunching [5][6][7], sub-Poissonian photon statistics [8,9], squeezing [10][11][12], photon echoes [13], and self-induced transparency [14][15][16]. With multilevel treatments of atoms, other phenomena are explained, such as quantum jumps [17][18][19][20] and laser cooling and trapping [21,22].…”