Wireless network control of interacting Rydberg atoms

We identify a relation between the dynamics of ultracold Rydberg gases in which atoms experience a strong dipole blockade and spontaneous emission, and a stochastic process that models certain wireless random-access networks. We then transfer insights and techniques initially developed for these wireless networks to the realm of Rydberg gases, and explain how the Rydberg gas can be driven into crystal formations using our understanding of wireless networks. Finally, we propose a method to determine Rabi frequencies (laser intensities) such that particles in the Rydberg gas are excited with specified target excitation probabilities, providing control over mixed-state populations.Comment: 6 pages, 7 figures; includes corrections and improvements from the peer-review proces

Design and experimental validation of a compact collimated Knudsen source

In this paper we discuss the design and performance of a collimated Knudsen source which has the benefit of a simple design over recirculating sources. Measurements of the flux, transverse velocity distribution and brightness at different temperatures were conducted to evaluate the performance. The scaling of the flux and brightness with the source temperature follow the theoretical predictions. The transverse velocity distribution in the transparent operation regime also agrees with the simulated data. The source was found able to produce a flux of $10^{14}$ s$^{-1}$ at a temperature of 433 K. Furthermore the transverse reduced brightness of an ion beam with equal properties as the atomic beam reads $1.7 \times 10^2$ A/(m${}^2$ sr eV) which is sufficient for our goal: the creation of an ultra-cold ion beam by ionization of a laser-cooled and compressed atomic rubidium beam

Rubidium Focused Ion Beam Induced Platinum Deposition

This work presents characterization of focused ion beam induced deposition (FIBID) of platinum using both rubidium and gallium ions. Trimethylplatinum [(MeCp)Pt(Me)3] was used as the deposition precursor. Under similar beam energies, 8.5 keV for Rb+ and 8.0 keV for Ga+, and beam current, near 10 pA, the two ion species deposited Pt films at 0.90 µm3/nC and 0.73 µm3/nC respectively. Energy-dispersive x-ray spectroscopy shows that the Rb+ FIBID-Pt consists of similar Pt contents (49% for Rb+ FIBID and 37% for Ga+ FIBID) with much lower primary ion contents (5% Rb and 27% Ga) than the Ga+ FIBID-Pt. The deposited material was also measured to have a resistivity of 8.1×104 µΩ· cm for the Rb+ FIBID-Pt and 5.7×103 µΩ· cm for the Ga+ FIBID-Pt

Study of surface damage in silicon by irradiation with focused rubidium ions using a cold-atom ion source

Cold-atom ion sources have been developed and commercialized as alternative sources for focused ion beams (FIBs). So far, applications and related research have not been widely reported. In this paper, a prototype rubidium FIB is used to study the irradiation damage of 8.5 keV beam energy Rb + ions on silicon to examine the suitability of rubidium for nanomachining applications. Transmission electron microscopy combined with energy dispersive x-ray spectroscopy is applied to silicon samples irradiated by different doses of rubidium ions. The experimental results show a duplex damage layer consisting of an outer layer of oxidation without Rb and an inner layer containing Rb mostly at the interface to the underlying Si substrate. The steady-state damage layer is measured to be 23.2(±0.3)  nm thick with a rubidium staining level of 7(±1) atomic percentage

Ultracold ion beams

Near-threshold photo-ionization of laser-cooled atoms provides a new class of ion sources. Characteristic of such sources is an extended source size combined with low angular spread. Whether ultracold sources are viable alternatives for, e.g., the Liquid-Metal Ion source depends on achieving operation at high brightness, low energy spread and/or with alternate ion species that can enable new applications. A number of these properties have already been investigated and some will be reviewed in the talk. Brightness achieved so far is well below that of the LMI and alternatives using laser-cooled atomic beams rather than traps are therefore being investigated. While these promise better performance on paper, disorder-induced heating and technical realization are challenges to overcome

Spontaneous formation of one-dimensional Rydberg crystals in an ultracold gas

Rydberg atoms have experimentally interestingproperties such as strong long-range Van der Waals interactions and the dipole blockade effect. In optical lattices the blockade effect ensures that only one Rydberg excitation per site is allowed, effectively creating a Rydberg crystal. We theoretically show that it is also possible for a one-dimensional Rydberg crystal to spontaneously form in a random ensemble of atoms, e.g. a magneto-optical trap. This is done using an\u3cbr/\u3eexisting Monte Carlo model [1] to simulate the excitation dynamics inside the intersection of two lasers for a two-step excitation scheme. With a blue-detuned laser for the upper transition, the first Rydberg excitation will occur after a relatively long time. That first Rydberg atom will then seed further Rydberg excitations, as the blockade effect shifts atoms at a certain distance into\u3cbr/\u3eresonance. If two dimensions of the laser intersection are smaller than the blockade radius, a one-dimensional Rydberg crystal will form

Radio frequency acceleration and manipulation of ultra-cold electron bunches

We are developing an ultra-fast and ultra-cold electron source based on a grating magneto optical trap, RF acceleration and RF (de-) compression techniques. The electrons will be created by near-threshold, femtosecond\u3cbr/\u3ephotoionization of a laser-cooled and trapped gas. The electron cloud is extracted from the plasma by a DC electric field and is further accelerated to energies of 100s keV by means of radio frequency acceleration techniques. This is possible while maintaining the electron beam quality, electron source temperatures of 10 K[1]. The setup can be used to create ultra-short\u3cbr/\u3eelectron bunches (i.e. 100 fs) by applying RF compression techniques. This makes the source ideal for time resolved pumpprobe crystallography of macromolecules. Secondly, the energy chirp can be removed by RF decompression techniques, resulting in low energy spread electron pulses. This\u3cbr/\u3ealso makes the source a viable candidate for electron microscopy and coherent imaging