Polarization-gradient cooling of 1D and 2D ion Coulomb crystals

Joshi, Manoj K.; Fabre, A.; Maier, C.; Brydges, Tiff; Kiesenhofer, D.; Hainzer, Helene; Blatt, R.; Roos, C. F.

doi:10.1088/1367-2630/abb912

Cited by 43 publications

(31 citation statements)

References 45 publications

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“…11 in Section IV). Therefore, we cool the longitudinal motional modes before and after sideband cooling of the radial modes, via polarizationgradient cooling [24]. Fig.…”

Section: B Laser Cooling and Motional Heating Of Long Stringsmentioning

confidence: 99%

Controlling long ion strings for quantum simulation and precision measurements

Kranzl,

Joshi,

Maier

et al. 2021

Preprint

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Scaling a trapped-ion based quantum simulator to a large number of ions creates a fullycontrollable quantum system that becomes inaccessible to numerical methods. When highly anisotropic trapping potentials are used to confine the ions in the form of a long linear string, several challenges have to be overcome to achieve high-fidelity coherent control of a quantum system extending over hundreds of micrometers. In this paper, we describe a setup for carrying out many-ion quantum simulations including single-ion coherent control that we use for demonstrating entanglement in 50-ion strings. Furthermore, we present a set of experimental techniques probing ion-qubits by Ramsey and Carr-Purcell-Meiboom-Gill (CPMG) pulse sequences that enable detection (and compensation) of power-line-synchronous magnetic-field variations, measurement of path length fluctuations, and of the wavefronts of elliptical laser beams coupling to the ion string.

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“…11 in Section IV). Therefore, we cool the longitudinal motional modes before and after sideband cooling of the radial modes, via polarizationgradient cooling [24]. Fig.…”

Section: B Laser Cooling and Motional Heating Of Long Stringsmentioning

confidence: 99%

Controlling long ion strings for quantum simulation and precision measurements

Kranzl,

Joshi,

Maier

et al. 2021

Preprint

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“…In this case, resonant scattering events due to the amplified spontaneous emission (ASE) of the laser diode represent an additional heating source. The final temperature after PGC would be limited by this effect, especially if the frequency detuning is increased in order to approach the theoretical temperature limit [32,37]. For large detunings, the lower cooling rate will be surpassed by the heating rate of the ASE background.…”

Section: Technique For Improving Pgc Efficiencymentioning

confidence: 99%

“…In an ideal case, the final mean phonon number is expected to be n 0 (ξ ) = ξ + 1/(4ξ ) − 1/2 for a single ion [37], where ξ = s ∆/(3ω z ) is a dimensionless parameter, ∆ is the frequency detuning of 393 nm light, and ω z is the trap frequency in the axial direction. The saturation parameter is defined as s = Ω 2 /2 Γ 2 /4+∆ 2 , with Γ = 2π × 23 MHz the width of the excited state P 3/2 and Ω the Rabi frequency.…”

Section: Technique For Improving Pgc Efficiencymentioning

confidence: 99%

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Robust Polarization Gradient Cooling of Trapped Ions

Li,

Wolf,

Klein

et al. 2021

Preprint

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We implement three-dimensional polarization gradient cooling of trapped ions. Counter-propagating laser beams near 393 nm impinge in lin ⊥ lin configuration, at a frequency below the S 1/2 to P 3/2 resonance in 40 Ca + . We demonstrate mean phonon numbers of 5.4(4) at a trap frequency of 2π × 285 kHz and 3.3(4) at 2π × 480 kHz, in the axial and radial directions, respectively. Our measurements demonstrate that cooling with laser beams detuned to lower frequencies from the resonance is robust against an elevated phonon occupation number, and thus works well for an initial ion motion far out of the Lamb-Dicke regime, for up to four ions, and for a micromotion modulation index β ≤ 0.1. Still, we find that the spectral impurity of the laser field influences both, cooling rates and cooling limits. Thus, a Fabry-Pérot cavity filter is employed for efficiently suppressing amplified spontaneous emission of the diode laser.

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“…The amount of such transverse E-field present in the lateral geometry may be small and insignificant for smaller 2D crystals [17], but may become significant for larger ion crystals. Lateral 2D crystals have been studied since the introduction of the linear Paul trap [21], leading to investigations of normal mode structure [22] and demonstrations of sub-Doppler cooling techniques [23]. Recent improvements in microfabricated ion trap capabilities have led to the formation of 2D crystals that can be cooled near the motional ground state [24].…”

Section: Introductionmentioning

confidence: 99%

Two-tone Doppler cooling of radial two-dimensional crystals in a radiofrequency ion trap

Kato,

Goel,

Lee

et al. 2021

Preprint

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We study the Doppler-cooling of radial two-dimensional (2D) Coulomb crystals of trapped barium ions in a radiofrequency trap. Ions in radial 2D crystals experience micromotion of an amplitude that increases linearly with the distance from the trap center, leading to a position-dependent frequency modulation of laser light in each ion's rest frame. We use two tones of Doppler-cooling laser light separated by approximately 100 MHz to efficiently cool distinct regions in the crystals with differing amplitudes of micromotion. This technique allows us to trap and cool more than 50 ions in a radial two-dimensional crystal. We also individually characterize the micromotion of all ions within the crystals, and use this information to locate the center of the trap and to determine the Matthieu parameters q x and q y .

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Polarization-gradient cooling of 1D and 2D ion Coulomb crystals

Cited by 43 publications

References 45 publications

Controlling long ion strings for quantum simulation and precision measurements

Controlling long ion strings for quantum simulation and precision measurements

Robust Polarization Gradient Cooling of Trapped Ions

Two-tone Doppler cooling of radial two-dimensional crystals in a radiofrequency ion trap

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