Precision Spectroscopy of Negative-Ion Resonances in Ultralong-Range Rydberg Molecules

Abstract

The level structure of negative-ions near the electron detachment limit dictates the low-energy scattering of an electron with the parent neutral atom. We demonstrate that a single ultracold atom bound inside a Rydberg orbit forming an ultralong-range Rydberg molecule provides an atomic-scale system which is highly sensitive to electron-neutral scattering and thus allows for detailed insights into the underlying near-threshold anion states. Our measurements reveal the so far unobserved fine structure of the 3 P J triplet of Rb − and allow us to extract parameters of the associated p-wave scattering resonances which deviate from previous theoretical estimates. Moreover, we observe a novel alignment mechanism for Rydberg molecules mediated by spin-orbit coupling in the negative ion. arXiv:1904.08372v2 [physics.atom-ph]

Pump-probe spectroscopy of Bose polarons: Dynamical formation and coherence

“…It would be intriguing to utilize PPS at finite temperature [108,109] and also in higher dimensions to explore the timeresolved formation of quasiparticles. As further perspectives, PPS could be exploited to unravel recondensation dynamics [110,111] in excited bands of optical lattices and the dynamics of vibrational states of ultra-long-range Rydberg molecules [112,113] to infer their lifetime.…”

Observation of spin-orbit-dependent electron scattering using long-range Rydberg molecules

“…On the left hand side of the wells steep butterfly PECs [13,27,28] cross through which arise due to a p-wave shape resonance, where the Rydberg electron with angular momentum L p = 1 resonantly interacts with the Rb ground state atom. This resonance occurs at a collision energy E avg r = 26.6 meV [24,29]. Due to the vicinity to the pwave shape resonance the ultralong-range Rydberg molecular states in the second outermost wells experience strong p-wave interaction and are thus very sensitive to L p · S coupling.…”

“…The interaction strength in each channel depends on the scattering lengths/volumes a(L p , S, J, k) = −k −(2L p +1) tan δ (L p , S, J, k), where δ (L p , S, J, k) are phase shifts of an electron with wave number k that scatters off a 87 Rb ground state atom. As a basis for our simulations we employ phase shift data from [24]. The wave number is calculated via the semiclassical relation k = 2/R − 1/n 2 eff .…”

Dressed Ion-Pair States of an Ultralong-Range Rydberg Molecule

“…This gargantuan molecule consists of a neutral perturber atom (B) bound to a highly excited Rydberg atom (A Ã ) [1][2][3][4]. The experimental observation of ULRMs [5][6][7] has led to their use in many diverse applications, e.g., as probes of chargeneutral interactions [8][9][10][11][12][13] or as impurities embedded in a many-body bath [14][15][16][17][18][19][20][21][22][23][24]. ULRMs exist because the Rydberg electron accumulates an appreciable phase shift as it scatters off of the perturber, which in turn produces an energy shift proportional to the S-wave scattering length [25,26].…”

“…Recent proposals exploit ULRMs, with similar bond lengths as HRS, to avoid these challenges [39,40]. In the vicinity of the perturber, the electronic wave function of the butterfly molecule and the metastable excited P anion have the same symmetry [9]. The electron can thus be transferred from the Rydberg state into the bound S anion state via a dipole-allowed transition, which also supplies the required energy to match the electron affinity and allow the reaction…”