Guiding of Rydberg atoms in a high-gradient magnetic guide

Abstract

We study the guiding of 87 Rb 59D 5/2 Rydberg atoms in a linear, high-gradient, two-wire magnetic guide. Time delayed microwave ionization and ion detection are used to probe the Rydberg atom motion. We observe guiding of Rydberg atoms over a period of 5 ms following excitation. The decay time of the guided atom signal is about five times that of the initial state. We attribute the lifetime increase to an initial phase of l-changing collisions and thermally induced RydbergRydberg transitions. Detailed simulations of Rydberg atom guiding reproduce most experimental observations and offer insight into the internal-state evolution.There has been a recent surge of interest in cold Rydberg atoms in a linear trapping geometry. Such systems present the possibility of creating one-dimensional spin chains by exciting atoms into high-lying Rydberg levels, which interact strongly due to their large dipole moments [1][2][3]. Rydberg crystals, which have been proposed in a frozen atomic gas using the Rydberg excitation blockade effect, may be an interesting application within a linear structure [4]. Entangled Rydberg atoms prepared in a linear guiding geometry could act as a shuttle for quantum information [5,6]. A one-dimensional trap or guide for Rydberg atoms could be used to further these types of research. Cold Rydberg atoms have been experimentally trapped using magnetic [7], electrostatic [8], and light fields [9]. Conservative trapping of Rydberg atoms in magnetic atom guides has been theoretically investigated in [10][11][12]. Theoretical calculations also indicate the possibility of stationary Rydberg atoms confined in magnetic traps and magnetoelectric traps [13][14][15]. These systems would allow one to study Rydberg gases in a one-dimensional geometry. The Rydberg-Rydberg interaction properties in such a system have been theoretically studied in [16]. In the present paper we report the first guiding of Rydberg atoms in a linear magnetic guide.Two parallel wires carrying equal currents guide cold atoms in low magnetic field seeking states along a linear guiding channel located between the guide wires, where the magnetic field approaches zero. Briefly, our 1.5 m long linear guide [17,18] operates with a magnetic field gradient of ∼1.5 kG/cm, which tightly confines a beam of 87 Rb atoms (prepared in the |F = 1, m F = −1 level of the 5S 1/2 ground-state) in the guiding channel. The forward velocity of the guided atoms is adjusted to ≈1 m/s. The ground state atoms have transverse and longitudinal temperatures of T x,y ≈ 400 µK and T z ≈ 1 mK, respectively. An excitation and detection region for Rydberg atoms is located 85 cm down the guide, illustrated in Fig. 1. We use a three-step Rydberg atom excitation process. A pulsed 780 nm beam (duration 10 µs) pumps the atoms from 5S 1/2 |F = 1, m F = −1 to F = 2. A second pulsed 780 nm beam (duration 5 µs) subsequently drives the atoms on the cycling transition into 5P 3/2 F ′ = 3. The atoms are excited from the 5P 3/2 level to the 59D 5/2 Rydberg level with a tunable, cont...

Coupled internal-state and center-of-mass dynamics of Rydberg atoms in a magnetic guide

“…Such an extension of the simulation could possibly be implemented in the future. An initial phase of state-mixing collisions, which would coincide in time with the Penning ionization phase, may explain why the fraction of Rydberg atoms left at late times is larger than expected from a collision-free model by a factor on the order of 10 [11].…”

“…The guide carries a beam of ^^Rb atoms in the |F = l,m/r = -1) sublevel of the 5Si/2 ground state. For details of the guide apparatus see [11,24,25]. The fiux of guided ground-state atoms is several 10^ s~'.…”

“…Using microwave ionization, we observed a sample lifetime of about 700 ßs, which exceeds the initial state lifetime by about a factor of 5. The increase in lifetime was attributed to internal-state redistribution into long-lived states [11].…”

“…Collisions play a role in the intemal-state distribution of the Rydberg atoms, as well. We have estimated that ~ 10% of the Rydberg atoms are Penning ionized [11], which implies that another ~ 10% are transferred into lower-« states due to Penning collisions. The Penning ionization rate is dependent on Rydberg-atom density (~2 x 10' "* m~^), thermal velocity (on the order of 0.4 m/s), and collision cross sections (on the order of 2 x 10"'^ m^ for n = 59).…”

“…Theoretically modeled systems include conservative trapping of Rydberg atoms in magnetic guides [4][5][6] and magnetoelectric trapping of stationary Rydberg atoms [7][8][9][10]. We have demonstrated guiding of Rydberg atoms in a linear, high-gradient magnetic atom guide [11]. Trapped Rydberg atoms are of interest in quantum information processing [12], antihydrogen experiments [13][14][15], and highprecision spectroscopy.…”