Ionization of Rydberg atoms at patterned electrode arrays

Lithographically patterned micrometer-scale electrode arrays are used to examine the effects of controlled surface electric fields on Rydberg-atom–surface interactions. The data show that application of modest electrode biases (∼±1 V) can lead to a transition from ionization of the incident atoms by short-range tunneling to field ionization well above the target surface. The resulting ions can be efficiently detected using ion collection fields whose strengths are substantially smaller than those required for direct field ionization pointing to the application of surface ionization in the detection of low-n Rydberg atoms. The data are analyzed with the aid of a Monte Carlo model and further demonstrate the critical role that local surface fields can play in governing the nature of atom-surface interactions

Rydberg atom scattering in K(12p)-CH3NO2 collisions: role of transient ion pair formation

Studies of K(12p)-CH3NO2 collisions reveal unusually strong Rydberg atom scattering which is attributed to the formation of transient K+..CH3NO2 − ion-pair states

Dynamics of heavy-Rydberg ion-pair formation in K(14p,20p)-SF6, CCl4ﾠcollisions

The dynamics of formation of heavy-Rydberg ion-pair states throughﾠelectron transferﾠin K(np)-SF6, CCl4ﾠcollisions is examined byﾠmeasuringﾠtheﾠvelocity,ﾠangular, and bindingﾠenergyﾠdistributions of the product ion pairs. The results areﾠanalyzedﾠwith the aid of a Monte Carlo collision code that models both the initial electron capture and the subsequent evolution of the ion pairs. The model simulations are in good agreement with the experimental data and highlight the factors such asﾠRydberg atomﾠsize, the kineticﾠenergyﾠof relativeﾠmotionﾠof theﾠRydberg atomﾠand target particle, and (in the case of attaching targets that dissociate) the energetics ofﾠdissociationﾠthat can be used to control the properties of the product ion-pair states

Rydberg blockade in a hot atomic beam

The dipole blockade of very-high-n, n∼300, strontium 5snf1F3 Rydberg atoms in a hot atomic beam is studied. For such high n, the blockade radius can exceed the linear dimensions of the excitation volume. Rydberg atoms formed inside the excitation volume can, upon leaving the region, continue to suppress excitation until they have moved farther away than the blockade radius. Moreover, the high density of states originating from the many magnetic sublevels associated with the F states results in a small but finite probability of excitation of L=3n1F3 atom pairs at small internuclear separations below the blockade radius. We demonstrate that these effects can be distinguished from one another by the distinct features they imprint on the Mandel Q parameter as a function of the duration of the exciting laser

Autoionization of very-high-n strontium Rydberg atoms

The autoionization of high n, n~280-430, strontium Rydberg states through excitation of the 5s 2S1/2→5p 2P1/2 transition in the core ion is investigated. The autoionization rates decrease rapidly as L is increased paving the way for production of long-lived two-electron-excited planetary atoms

Lifetimes of ultra-long-range strontium Rydberg molecules

The lifetimes of the lower-lying vibrational states of ultra-long-range strontium Rydberg molecules comprising one ground-state 5s2 1S0 atom and one Rydberg atom in the 5s38s3S1 state are reported. The molecules are created in an ultracold gas held in an optical dipole trap and their numbers determined using field ionization, the product electrons being detected by a microchannel plate. The measurements show that, in marked contrast to earlier measurements involving rubidium Rydberg molecules, the lifetimes of the low-lying molecular vibrational states are very similar to those of the parent Rydberg atoms. This results because the strong p-wave resonance in low-energy electron-rubidium scattering, which strongly influences the rubidium molecular lifetimes, is not present for strontium. The absence of this resonance offers advantages for experiments involving strontium Rydberg atoms as impurities in quantum gases and for testing of theories of molecular formation and decay

Lifetimes of ultralong-range strontium Rydberg molecules in a dense Bose-Einstein condensate

The lifetimes and decay channels of ultralong-range Rydberg molecules created in a dense Bose-Einstein condensate are examined by monitoring the time evolution of the Rydberg population using field ionization. Studies of molecules with values of the principal quantum number, n , in the range n = 49 to n = 72 that contain tens to hundreds of ground-state atoms within the Rydberg electron orbit show that their presence leads to marked changes in the field ionization characteristics. The Rydberg molecules have lifetimes of ∼ 1 − 5 μ s , their destruction being attributed to two main processes: formation of Sr 2 + ions through associative ionization and dissociation induced through L -changing collisions. The observed loss rates are consistent with a reaction model that emphasizes the interaction between the Rydberg core ion and its nearest-neighbor ground-state atom. The measured lifetimes place strict limits on the time scales over which studies involving Rydberg species in cold, dense atomic gases can be undertaken and limit the coherence times for such measurements

Fine-Scale Mapping of the 5q11.2 Breast Cancer Locus Reveals at Least Three Independent Risk Variants Regulating MAP3K1

Peer reviewe

MicroRNA Related Polymorphisms and Breast Cancer Risk

Peer reviewe

Associations of obesity and circulating insulin and glucose with breast cancer risk: a Mendelian randomization analysis.

BACKGROUND: In addition to the established association between general obesity and breast cancer risk, central obesity and circulating fasting insulin and glucose have been linked to the development of this common malignancy. Findings from previous studies, however, have been inconsistent, and the nature of the associations is unclear. METHODS: We conducted Mendelian randomization analyses to evaluate the association of breast cancer risk, using genetic instruments, with fasting insulin, fasting glucose, 2-h glucose, body mass index (BMI) and BMI-adjusted waist-hip-ratio (WHRadj BMI). We first confirmed the association of these instruments with type 2 diabetes risk in a large diabetes genome-wide association study consortium. We then investigated their associations with breast cancer risk using individual-level data obtained from 98 842 cases and 83 464 controls of European descent in the Breast Cancer Association Consortium. RESULTS: All sets of instruments were associated with risk of type 2 diabetes. Associations with breast cancer risk were found for genetically predicted fasting insulin [odds ratio (OR) = 1.71 per standard deviation (SD) increase, 95% confidence interval (CI) = 1.26-2.31, p  =  5.09  ×  10-4], 2-h glucose (OR = 1.80 per SD increase, 95% CI = 1.3 0-2.49, p  =  4.02  ×  10-4), BMI (OR = 0.70 per 5-unit increase, 95% CI = 0.65-0.76, p  =  5.05  ×  10-19) and WHRadj BMI (OR = 0.85, 95% CI = 0.79-0.91, p  =  9.22  ×  10-6). Stratified analyses showed that genetically predicted fasting insulin was more closely related to risk of estrogen-receptor [ER]-positive cancer, whereas the associations with instruments of 2-h glucose, BMI and WHRadj BMI were consistent regardless of age, menopausal status, estrogen receptor status and family history of breast cancer. CONCLUSIONS: We confirmed the previously reported inverse association of genetically predicted BMI with breast cancer risk, and showed a positive association of genetically predicted fasting insulin and 2-h glucose and an inverse association of WHRadj BMI with breast cancer risk. Our study suggests that genetically determined obesity and glucose/insulin-related traits have an important role in the aetiology of breast cancer