Sensitivity of ultracold-atom scattering experiments to variation of the fine-structure constant

Abstract

We present numerical calculations for cesium and mercury to estimate the sensitivity of the scattering length to the variation of the fine structure constant α. The method used follows ideas Chin and Flambaum [Phys. Rev. Lett. 96, 230801 (2006)], where the sensitivity to the variation of the electron to proton mass ratio, β, was considered. We demonstrate that for heavy systems, the sensitivity to variation of α is of the same order of magnitude as to variation of β. Near narrow Feshbach resonances the enhancement of the sensitivity may exceed nine orders of magnitude.

Direct Observation of Resonant Scattering Phase Shifts and Their Energy Dependence

“…Increasing the collision energy allows us to resolve resonances that overlap at threshold. Precise measurements of scattering phase shifts through a resonance will very accurately determine the resonance position, giving a highly precise determination of the atomic interactions [5] and a potential route to stringent limits on the time variation of fundamental constants [13,14].We directly measure scattering phase shifts by preparing cesium atoms in coherent superpositions of the two clock states and detecting the phase shift of these coherences after the clock atoms scatter off atoms prepared in a pure 'target' state ( Fig. 2 inset) [12].…”

“…In turn, these can place stringent limits on the time variations of underlying fundamental forces [13,14].…”

“…Increasing the collision energy allows us to resolve resonances that overlap at threshold. Precise measurements of scattering phase shifts through a resonance will very accurately determine the resonance position, giving a highly precise determination of the atomic interactions [5] and a potential route to stringent limits on the time variation of fundamental constants [13,14].…”

Atomic Clock Measurements of Quantum Scattering Phase Shifts Spanning Feshbach Resonances at Ultralow Fields

“…This is the energy scale for collisions in PHARAO, a microgravity laser-cooled cesium clock scheduled to launch soon as part of the ACES mission [20]. Additionally, precise measurements of scattering phase shifts, or equivalently scattering lengths, near narrow Feshbach resonances may provide high sensitivity to the time variation of fundamental constants [21,22].…”

Enhanced association and dissociation of heteronuclear Feshbach molecules in a microgravity environment

“…Their heteronuclear counterparts are an important ingredient for the creation of ultracold polar molecules [13][14][15][16][17][18][19][20][21][22][23] and can be used to study universal few-body phenomena [24][25][26][27][28][29][30]. Additionally, Feshbach molecules can be used as a source of entangled states [31][32][33][34][35][36][37][38][39][40][41], or test the variation of fundamental constants with unprecedented sensitivity [42][43][44][45].…”