Quasideterministic Generation of Entangled Atoms in a Cavity

Hong, Jin-Woong; Lee, Hai‐Woong

doi:10.1103/physrevlett.89.237901

Cited by 92 publications

(67 citation statements)

References 22 publications

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“…Provided the time the photons need to travel from the cavities to the detectors is much shorter than their mutual coherence time (as is in fact the case for mode B in our experiment), the first photodetection would establish an entanglement between the distant atom-cavity systems [12,13,14,15], since the states |1 A,B and |0 A,B refer in this case to these systems. This entanglement would live until it is destructively probed by a second photodetection.…”

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confidence: 77%

Quantum Beat of Two Single Photons

et al. 2004

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The interference of two single photons impinging on a beam splitter is measured in a time-resolved manner. Using long photons of different frequencies emitted from an atom-cavity system, a quantum beat with a visibility close to 100% is observed in the correlation between the photodetections at the output ports of the beam splitter. The time dependence of the beat amplitude reflects the coherence properties of the photons. Most remarkably, simultaneous photodetections are never observed, so that a temporal filter allows one to obtain perfect twophoton coalescence even for non-perfect photons. 03.67.Mn, 42.50.Xa, 42.50.Dv, 42.65.Dr The quantum nature of light impressively manifests itself in the fourth-order interference of two identical and mutually coherent single photons that impinge simultaneously on a beam splitter (BS). The photons coalesce and both leave the beam splitter in the same direction. Hong et al. first demonstrated this phenomenon with photon pairs from parametric down conversion [1] and Santori et al. used the same effect to show the indistinguishability of independently generated photons that are successively emitted from a quantum dot embedded in a micro cavity [2]. In all experiments performed so far, the photons were short compared to the time resolution of the employed detectors, so that interference phenomena were only observed as a function of the spatial delay between the interfering photons [3].To investigate the temporal dynamics behind this interference phenomenon, we now use an adiabatically driven strongly coupled atom-cavity system as single-photon emitter [4,5,6,7]. Photons are generated by a unitary process, so that their temporal and spectral properties can be arbitrarily adjusted. In fact, the duration of the photons used in our experiment exceeds the time resolution of the employed singlephoton counters by three orders of magnitude. This allows for the first time an experimental investigation of fourth-order interference phenomena in a time-resolved manner with photons arriving simultaneously at the beam splitter [8]. We find perfect interference even if the frequency difference between the two photons exceeds their bandwidths. This surprising result is very robust against all kinds of fluctuations and opens up new possibilities in all-optical quantum information processing [9].The principal scheme of the experiment is sketched in Fig. 1. We consider an initial situation where two single photons in modes A and B impinge simultaneously on a BS. In front of the BS, we distinguish states |1 A,B and |0 A,B , where either a photon is present or where it has been annihilated by transmission through the BS and subsequent detection by detector C or D. Mode A is an extended spatiotemporal photonic field mode, traveling along an optical fiber, which initially carries a photon. The photon in mode B emerges from a strongly coupled atom-cavity system, which is driven in a way that the photon is deterministically generated by a vacuum-stimulated Raman transition between two long-lived S...

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Quantum Beat of Two Single Photons

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“…Although the trap loading is not deterministic, N can be measured quickly compared to the subsequent trapping time 3 s [9]. These new techniques could assist in the realization of various protocols in quantum information science, including probabilistic schemes for entangling multiple atoms in a cavity [11][12][13]. Although our current investigation has centered on the case of small N 3, there are reasonable prospects for an extension to higher values N & 10 [see Fig.…”

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confidence: 99%

“…However, many protocols in QIS require multiple atoms to be trapped within the same cavity, with ''quantum wiring'' between internal states of the various atoms accomplished by way of strong coupling to the cavity field [6,[11][12][13]. Clearly, the experimental ability to determine the number of trapped atoms coupled to a cavity is a critical first step toward the realization of diverse goals in QIS.…”

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Determination of the Number of Atoms Trapped in an Optical Cavity

et al. 2004

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The number of atoms trapped within the mode of an optical cavity is determined in real time by monitoring the transmission of a weak probe beam. Continuous observation of atom number is accomplished in the strong coupling regime of cavity quantum electrodynamics and functions in concert with a cooling scheme for radial atomic motion. The probe transmission exhibits sudden steps from one plateau to the next in response to the time evolution of the intracavity atom number, from N 3 to N 2 ! 1 ! 0 atoms, with some trapping events lasting over 1 s. DOI: 10.1103/PhysRevLett.93.143601 PACS numbers: 42.50.Pq, 03.67.-a, 32.80.Pj Cavity quantum electrodynamics (QED) provides a setting in which atoms interact predominantly with light in a single mode of an electromagnetic resonator [1,2]. Not only can the light from this mode be collected with high efficiency [3], but the associated rate of optical information for determining atomic position can greatly exceed the rate of free-space fluorescent decay employed for conventional imaging [4]. Moreover, the regime of strong coupling, in which coherent atom-cavity interactions dominate dissipation, offers a unique setting for the study of open quantum systems [5]. Dynamical processes enabled by strong coupling in cavity QED provide powerful tools in the emerging field of quantum information science (QIS), including for the realization of quantum computation [6] and distributed quantum networks [7].With these prospects in mind, experiments in cavity QED have made great strides in trapping single atoms in the regime of strong coupling [4,[8][9][10]. However, many protocols in QIS require multiple atoms to be trapped within the same cavity, with ''quantum wiring'' between internal states of the various atoms accomplished by way of strong coupling to the cavity field [6,[11][12][13]. Clearly, the experimental ability to determine the number of trapped atoms coupled to a cavity is a critical first step toward the realization of diverse goals in QIS. Experimental efforts to combine ion trap technology with cavity QED are promising [14], but have not yet reached the regime of strong coupling.In this Letter, we report measurements in which the number of atoms trapped inside an optical cavity is observed in real time. After initial loading of the intracavity dipole trap with N 5 atoms, the decay of atom number N 3 ! 2 ! 1 ! 0 is monitored via the transmission of a near-resonant probe beam, with the transmitted light exhibiting a cascade of ''stair steps'' as successive atoms leave the trap. After the probabilistic loading stage, the time required for the determination of a particular atom number N 1; 2; 3 is much shorter than the mean interval over which the N atoms are trapped. Hence, this scheme can be used to prepare a precise number of trapped intracavity atoms for subsequent experiments in QIS, for which the time scales g ÿ1 10 ÿ8 s 3 s ), where is the atomic trapping time [9] and hg is the atom-field interaction energy. In addition, it requires none of the imaging optics or sh...

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“…See are strongly coupled to left and right circularly polarizing cavity modes, respectively. The atomic level structure can be achieved by Zeeman sublevels [27] and has been realized to entangled two atoms [28]. We suppose the two atoms are all initially prepared in their excited states and cavity in the vacuum state.…”

Section: Two -Atom In One Cavitymentioning

confidence: 99%