Laser Trapping of Circular Rydberg Atoms

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Laser Trapping of Circular Rydberg Atoms

R. G. Cortiñas, M. Favier, B. Ravon, P. Méhaignerie, Y. Machu, J. M. Raimond, C. Sayrin, and M. Brune

Phys. Rev. Lett. 124, 123201 – Published 23 March 2020

Abstract

Rydberg atoms are remarkable tools for quantum simulation and computation. They are the focus of an intense experimental activity, mainly based on low-angular-momentum Rydberg states. Unfortunately, atomic motion and levels lifetime limit the experimental timescale to about $100 μ s$ . Here, we demonstrate two-dimensional laser trapping of long-lived circular Rydberg states for up to 10 ms. Our method is very general and opens many opportunities for quantum technologies with Rydberg atoms. The 10 ms trapping time corresponds to thousands of interaction cycles in a circular-state-based quantum simulator. It is also promising for quantum metrology and quantum information with Rydberg atoms, by bringing atom-field interaction times into unprecedented regimes.

Received 6 November 2019
Accepted 2 March 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.123201

Physics Subject Headings (PhySH)

Cooling & trapping

Rydberg atoms & molecules

Atom & ion cooling Atom & ion trapping & guiding Cryogenics Microwave techniques Optical lattices & traps

General PhysicsAtomic, Molecular & Optical

Authors & Affiliations

R. G. Cortiñas ^†, M. Favier^†, B. Ravon, P. Méhaignerie, Y. Machu, J. M. Raimond , C. Sayrin ^*, and M. Brune

Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université, 11 place Marcelin Berthelot, F-75231 Paris, France

^*Corresponding author. clement.sayrin@lkb.ens.fr
^†These authors contributed equally to this work.

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Vol. 124, Iss. 12 — 27 March 2020

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Images

Figure 1
(a) Experimental setup with axes definition. The blue and red Rydberg excitation lasers cross in the cold atom cloud (green), about 4 mm away from the surface of the MOT mirror. The electrode $V_{s}$ applies the electric field $F$ and the ionization field. The ${Rb}^{+}$ ions (violet dashed line) are guided toward the Channeltron $C$ by the deflection electrode $V_{d}$ . Four additional electrodes (only two, ${rf}_{1}$ and ${rf}_{2}$ , are shown for clarity) apply the circular state preparation rf field and a static electric-field gradient $\partial_{z} F$ . The LG beam (purple) traps the Rydberg atoms (dark blue) (b) Simplified level scheme. (Left) Two-photon laser excitation (solid arrows) and circular state preparation (dotted arrow). (Right) Partial diagram of the Stark levels in the $n = 50$ and $n = 52$ manifolds sorted by $m$ values. The arrows represent the microwave transitions ${MW}_{S}$ (level selection) and ${MW}_{P}$ (probe). (c) Timing of the experiment (not to scale). (Top, from left to right) Main events. Laser excitation (light blue), circular state preparation (gray), selection pulse ${MW}_{S}$ (dark green), partial ionization (light yellow), probe pulse ${MW}_{P}$ (dark green), field ionization (dark yellow). (Middle) LG beam intensity versus time for the trapping experiment. (Bottom) LG intensity for the trap oscillation-frequency measurement.
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Figure 2
Laser trapping. (a) FWHM $σ_{P}$ of the probe transition as a function of the delay time $τ$ for untrapped (red rectangles) and trapped (blue circles) atoms. In all panels, full symbols correspond to an average atom number ${\bar{N}}_{0}$ . Open symbols correspond to the same measurements with about ${\bar{N}}_{0} / 2$ atoms. The lines result from a model of the Rydberg atoms expansion for untrapped (red) and trapped (blue) atoms, with $\bar{N} = {\bar{N}}_{0}$ (solid) or $\bar{N} \approx {\bar{N}}_{0} / 2$ (dotted). (b) Total population of $| 50 C ⟩$ at $t = τ$ , before the ${MW}_{P}$ probe pulse for trapped (blue circles) and untrapped (red rectangles) atoms. The lines correspond to an exponential fit with a single decay time of $4.6 \pm 0.3 ms$ . The number of atoms at $t = 0$ , uncorrected from detection efficiency, is $\bar{N} = {\bar{N}}_{0} = 0.18 \pm 0.01$ for solid symbols and $\bar{N} = 0.08 \pm 0.01 \approx {\bar{N}}_{0} / 2$ for open symbols. (c) Integrated area $A_{P}$ of the ${MW}_{P}$ probe spectrum for trapped (blue) and untrapped (red) atoms. Error bars correspond to $1 − σ$ standard error deviation.
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Figure 3
Trap frequency measurement. Blue circles with statistical error bars: number of atoms, $N_{52 E}$ in $| 52 E ⟩$ , as a function of the time $Δ t$ at which the trap is switched off. (Blue line) Damped sinusoidal fit to the data.
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Figure 4
Test of atomic coherence. Microwave spectrum of the two-photon $| 50 C ⟩ \to | 52 C ⟩$ transition for trapped (blue circles) and untrapped (red rectangles) atoms (statistical error bars) with $ν_{offset} = 49.639 071 GHz$ . The fraction of atoms transferred to $| 52 C ⟩$ is plotted with respect to the detuning of the microwave source from resonance. The red points have been shifted upward for clarity.
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