Trapping Rydberg Atoms in an Optical Lattice

Rubidium Rydberg atoms are laser excited and subsequently trapped in a one-dimensional optical lattice (wavelength 1064 nm). Efficient trapping is achieved by a lattice inversion immediately after laser excitation using an electro-optic technique. The trapping efficiency is probed via analysis of the trap-induced shift of the two-photon microwave transition $50S\to 51S$. The inversion technique allows us to reach a trapping efficiency of 90%. The dependence of the efficiency on the timing of the lattice inversion and on the trap laser power is studied. The dwell time of $50D_{5/2}$ Rydberg atoms in the lattice is analyzed using lattice-induced photoionization.

Figure 1

Sketch of the experimental setup. Rydberg atoms are optically excited at potential maxima of a one-dimensional Rydberg-atom optical lattice. An electro-optic modulator (EOM) is used to switch the lattice polarization by 90° from $A$ to $B$ immediately after excitation, resulting in lattice inversion and efficient Rydberg-atom trapping.

Figure 2

(a) Experimental microwave spectra for $P=0.8\mathrm{W}$ and optical pulse length ${\tau }_{\mathrm{ex}}=0.5\mu \mathrm{s}$ for the indicated values of $\eta =P_{\mathrm{trans}}/P$ (spectra offset for clarity). (b) Lattice potentials after inversion vs position for several of the $\eta$ values used in panel (a). The fully inverted case, $\eta =1$, leads to the strongest blueshifted signal component, indicative of most efficient Rydberg-atom trapping.

Figure 3

(a) Simulated microwave spectra for the indicated values of $\eta =P_{\mathrm{trans}}/P$ and the same conditions as in Fig. 2. (b) Simulated atomic trajectories for the cases of no inversion (bottom) and complete inversion (top). The Rydberg-atom trapping potential is shown in the background on a scale from 3 MHz (white) to 15 MHz (dark).

Figure 4

Effect of varying excitation pulse length ${\tau }_{\mathrm{ex}}$ and lattice power $P$ on trapping efficiency for $\eta =1$ (complete lattice inversion). (a) Varying ${\tau }_{\mathrm{ex}}$ at fixed $P=0.8\mathrm{W}$. (b) Varying $P$ at fixed ${\tau }_{\mathrm{ex}}=0.5\mu \mathrm{s}$.

Figure 5

Measurements of lattice-induced photoionization of $50D_{5/2}$ Rydberg atoms in an optical lattice ($P=0.8\mathrm{W}$). Atom number vs time after excitation without (black squares) and with lattice (red circles) for $\eta =0$ (a) and $\eta =1$ (b). The data without lattice are fitted with an exponential function (lifetime $100\pm 15\mu \mathrm{s}$). (c) Symbols: ratios $F(t)$ obtained from the experimental data in panels (a) and (b). Lines: simulation results.