Spin-Polarized Atoms in a Circularly Polarized Optical Dipole Trap

Corwin, Kristan L.; Kuppens, S. J. M.; Cho, D.; Wieman, Carl

doi:10.1103/physrevlett.83.1311

Cited by 85 publications

(42 citation statements)

References 15 publications

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“…13 and 14 for x = 0.17 and x = 0.83. The excess fluctuations g ͑2͒ ͑͒ տ 1 extending over Ӎ ±1 s appear to be related to the interplay of atomic motion and optical pumping into dark states [44], as well as Larmor precession that arises from residual ellipticity in polarization of the intracavity FORT [43,45].…”

Section: A Mean Intracavity Photon Number As a Function Of Pump Intementioning

confidence: 99%

“…The ⍀ 3,4 beams tend to optically pump the atom into dark states, with this pumping counterbalanced by atomic motion leading to cooling [44] and by any residual magnetic field. In our case, imperfections in the FORT polarization [42,43] result in a small pseudomagnetic field along the cavity axis y [45] with peak magnitude B y F Ӎ 0.75 G. This pseudofield B y F is included in our simulations and tends to counteract optical pumping by the ⍀ 3,4 beams into dark states for linear polarization in the x-z plane, 3x = 3z = 4x = 4z = / 2, but has no effect for polarization along the cavity axis y, 3x = 3z = 4x = 4z =0. Overall, the operation of our driven atom-cavity system involves an interplay of cycling through the levels g3 → e3 → g4 → e4 → g3 to achieve output light on the e3 → g4 transition, and of polarization gradient cooling for extended trapping times.…”

Section: Quantum Theory Including Zeeman States and Two Cavity Modesmentioning

confidence: 99%

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Comparison of theory and experiment for a one-atom laser in a regime of strong coupling

et al. 2004

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Our recent paper reports the experimental realization of a one-atom laser in a regime of strong coupling [J. McKeever, A. Boca, A. D. Boozer, J. R. Buck, and H. J. Kimble, Nature (London) 425, 268 (2003)]. Here we provide the supporting theoretical analysis relevant to the operating regime of our experiment. By way of a simplified four-state model, we investigate the passage from the domain of conventional laser theory into the regime of strong coupling for a single intracavity atom pumped by coherent external fields. The four-state model is also employed to exhibit the vacuum-Rabi splitting and to calculate the optical spectrum. We next extend this model to incorporate the relevant Zeeman hyperfine states as well as a simple description of the pumping processes in the presence of polarization gradients and atomic motion. This extended model is employed to make quantitative comparisons with our earlier measurements for the intracavity photon number versus pump strength and for the photon statistics as expressed by the intensity correlation function g ͑2͒ ͑͒.

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Section: A Mean Intracavity Photon Number As a Function Of Pump Intementioning

confidence: 99%

Section: Quantum Theory Including Zeeman States and Two Cavity Modesmentioning

confidence: 99%

Comparison of theory and experiment for a one-atom laser in a regime of strong coupling

et al. 2004

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“…Our system is in the strong coupling regime of cavity QED g 0 ≫ (γ, κ) [1], with critical photon and atom numbers n 0 ≡ γ 2 /(2g 2 0 ) ≈ 0.0029 and N 0 ≡ 2κγ/g 2 0 ≈ 0.018. The intracavity FORT is driven by a linearly polarized input field E F ORT at λ F = 935.6 nm [24], resulting in nearly equal ac-Stark shifts for all Zeeman states in the 6S 1/2 , F = 3, 4 manifold [25]. At an antinode of the field, the peak value of the trapping potential for these states is U 0 /h = −39 MHz for all our measurements.…”

Section: Figmentioning

confidence: 99%

Observation of the Vacuum Rabi Spectrum for One Trapped Atom

Boca

Miller²,

Birnbaum³

et al. 2004

Phys. Rev. Lett.

387

320

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The transmission spectrum for one atom strongly coupled to the field of a high finesse optical resonator is observed to exhibit a clearly resolved vacuum-Rabi splitting characteristic of the normal modes in the eigenvalue spectrum of the atom-cavity system. A new Raman scheme for cooling atomic motion along the cavity axis enables a complete spectrum to be recorded for an individual atom trapped within the cavity mode, in contrast to all previous measurements in cavity QED that have required averaging over many atoms.A cornerstone of optical physics is the interaction of a single two-level atom with the electromagnetic field of a high quality resonator. Of particular importance is the regime of strong coupling, for which the frequency scale g associated with reversible evolution for the atom-cavity system exceeds the rates (γ, κ) for irreversible decay of atom and cavity field, respectively [1]. In the domain of strong coupling, a photon emitted by the atom into the cavity mode is likely to be repeatedly absorbed and reemitted at the single-quantum Rabi frequency 2g before being irreversibly lost into the environment. This oscillatory exchange of excitation between atom and cavity field results from a normal mode splitting in the eigenvalue spectrum of the atom-cavity system [2] which is manifest in emission [3] and absorption [4] spectra, and has been dubbed the vacuum-Rabi splitting [3].Strong coupling in cavity QED as evidenced by the vacuum-Rabi splitting provides enabling capabilities for quantum information science, including for the implementation of scalable quantum computation [5,6], for the realization of distributed quantum networks [7,8], and more generally, for the study of open quantum systems [9]. Against this backdrop, experiments in cavity QED have made great strides over the past two decades to achieve strong coupling [10]. The vacuum-Rabi splitting for single intracavity atoms has been observed with atomic beams in both the optical [11,12,13] and microwave regimes [14]. The combination of laser cooled atoms and large coherent coupling has enabled single atomic trajectories to be monitored in real time with high signal-to-noise ratio, so that the vacuum-Rabi spectrum could be obtained from atomic transit signals produced by single atoms [15]. A significant advance has been the trapping of individual atoms in an optical cavity in a regime of strong coupling [16,17], with the vacuum-Rabi splitting first evidenced for single trapped atoms in Ref.[16] and the entire transmission spectra recorded in Ref. [18].Without exception these prior single atom experiments related to the vacuum-Rabi splitting in cavity QED [11,12,13,14,15,16,17,18] have required averaging over trials with many atoms to obtain quantitative spec- tral information, even if individual trials involved only single atoms (e.g., 10 5 atoms were required to obtain a spectrum in Ref. [14] and > 10 3 atoms were needed in Ref. [18]). By contrast, the implementation of complex algorithms in quantum information science requires the capabili...

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“…Vector light shifts arising from elliptical light polarization [20] are known to be a major obstacle to cooling and manipulating atoms in optical dipole traps. In the paraxial limit, the vector light shift can be eliminated by using a linearly polarized trapping beam.…”

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Coherence and Raman Sideband Cooling of a Single Atom in an Optical Tweezer

et al. 2013

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We investigate quantum control of a single atom in an optical tweezer trap created by a tightly focused optical beam. We show that longitudinal polarization components in the dipole trap arising from the breakdown of the paraxial approximation give rise to significant internal-state decoherence. We show that this effect can be mitigated by appropriate choice of magnetic bias field, enabling Raman sideband cooling of a single atom close to its three-dimensional ground state in an optical trap with a beam waist as small as w = 900 nm. We achieve vibrational occupation numbers of nr = 0.01 andna = 8 in the radial and axial directions of the trap, corresponding to an rms size of the atomic wavepacket of 24 nm and 270 nm, respectively. This represents a promising starting point for future hybrid quantum systems where atoms are placed in close proximity to surfaces.Single atoms in "optical tweezer" traps [1] are a promising resource for various applications in quantum science and engineering. They can be individually moved [2], manipulated [3,4], and read-out [5] in a manner similar to trapped ions. At the same time, they may be strongly coupled to photonic [6,7], plasmonic [8], or other solid-state systems [9][10][11], opening a new frontier for the realization of quantum networks and hybrid quantum systems. These intriguing applications require trapping single ultra-cold atoms near surfaces at distances well below an optical wavelength. While this is challenging for ions [12], and magnetically trapped atoms [9,13], it is readily achievable with neutral atoms in optical dipole traps.The collisional blockade regime [1] of optical dipole traps is an attractive starting point for such experiments because it provides a simple way to load and tightly confine single atoms starting with only a conventional optical molasses. In several experiments, it has been found that the temperature of an atom loaded from a molasses into an optical dipole trap in the collisional blockade regime is in the range 30 µK to 180 µK [3,4,7,[14][15][16][17]. This elevated temperature compared to free-space cooling has been identified as a limiting factor in many recent experiments, as the thermal motion reduces the coherence time [3,4,16] and impedes full quantum control [17,18]. Moreover, lower temperatures and a reduction in the spatial extent of the atomic wavepacket are necessary to control the atom at sub-wavelength distances from a surface, or to implement proposed quantum gates using collisional interactions between two ground state atoms [19].One major challenge to laser cooling and quantum control are polarization effects associated with the breakdown of the paraxial approximation in very tightly focused optical dipole traps. Vector light shifts arising from elliptical light polarization [20] are known to be a major obstacle to cooling and manipulating atoms in optical dipole traps. In the paraxial limit, the vector light shift can be eliminated by using a linearly polarized trapping beam. However, in the tightly focused regime, nonpara...

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Spin-Polarized Atoms in a Circularly Polarized Optical Dipole Trap

Cited by 85 publications

References 15 publications

Comparison of theory and experiment for a one-atom laser in a regime of strong coupling

Comparison of theory and experiment for a one-atom laser in a regime of strong coupling

Observation of the Vacuum Rabi Spectrum for One Trapped Atom

Coherence and Raman Sideband Cooling of a Single Atom in an Optical Tweezer

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