Experimental demonstration of a Rydberg-atom beam splitter

Inhomogeneous electric fields generated above two-dimensional electrode structures have been used to transversely split beams of helium Rydberg atoms into pairs of spatially separated components. The atomic beams had initial longitudinal speeds of between 1700 and 2000 m/s and were prepared in Rydberg states with principle quantum number $n=52$ and electric dipole moments of up to 8700 D by resonance-enhanced two-color two-photon laser excitation from the metastable $1s2s{}^3{S}_1$ level. Upon exiting the beam splitter the ensembles of Rydberg atoms were separated by up to 15.6 mm and were detected by pulsed electric field ionization. Effects of amplitude modulation of the electric fields of the beam splitter were shown to cause particle losses through transitions into unconfined Rydberg-Stark states.

Figure 1

(a) Schematic diagram of a Rydberg-atom beam splitter. (b) Electric-field distribution in the $xz$ plane of the beam splitter at $y=1.4$ mm for $V_{\mathrm{g}}=30$ V (see text for details). The electric field strength indicated by the white contour lines in (b) is displayed in intervals of 20 V/cm.

Figure 2

Schematic diagram of the experimental setup (not to scale). Rydberg-state photoexcitation occurs between electrodes E1 and E2. The excited Rydberg atoms are detected by pulsed electric field ionization upon the application of a pulsed potential $V_{\mathrm{ion}}=+500$ V to E3 with the resulting ${\mathrm{He}}^{+}$ ions accelerated through the aperture in E4 to the microchannel plate (MCP) detector.

Figure 3

(a) ${\mathrm{He}}^{+}$ time-of-flight distributions recorded following pulsed electric field ionization (PFI) in the detection region of the apparatus when $V_{\mathrm{g}}=0$ V (black curve), 15 V (blue curve), and 22 V (red curve) as indicated. The inset axis shows the calculated relative positions of the atoms in the $x$ dimension at the time of PFI. (b) Simulated spatial distributions of Rydberg atoms in the $x$ dimension in the detection region at the time of PFI. The data for $V_{\mathrm{g}}=0$ V (dashed black curve) have been scaled by a factor of 0.45 as indicated.

Figure 4

Normalized ${\mathrm{He}}^{+}$ time-of-flight distributions for a range of beam-splitter operating potentials, $V_{\mathrm{g}}$, for (a) a low-field-seeking Rydberg-Stark state for which ${\mu }_{\mathrm{elec}}=8700$ D, and (b) a center Stark state with ${\mu }_{\mathrm{elec}}\simeq 0$ D. The color scale in (b) is common to both plots.

Figure 5

${\mathrm{He}}^{+}$ time-of-flight distributions for $V_{\mathrm{g}}=20$ V with no amplitude modulation (black curve) and with modulations of $V_{\mathrm{mod}}^{\mathrm{pp}}=56$ and 280 mV (blue and red curves, respectively) at 100 MHz.