Observation of Resonant Monopole-Dipole Energy Transfer between Rydberg Atoms and Polar Molecules

Resonant energy transfer (RET) between the equal parity 1s65s <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mmultiscripts> <a:mrow> <a:msub> <a:mrow> <a:mi mathvariant="normal">S</a:mi> </a:mrow> <a:mrow> <a:mn>1</a:mn> </a:mrow> </a:msub> </a:mrow> <a:mprescripts/> <a:none/> <a:mrow> <a:mn>3</a:mn> </a:mrow> </a:mmultiscripts> </a:mrow> </a:math> and 1s66s <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"> <d:mrow> <d:mmultiscripts> <d:mrow> <d:msub> <d:mrow> <d:mi mathvariant="normal">S</d:mi> </d:mrow> <d:mrow> <d:mn>1</d:mn> </d:mrow> </d:msub> </d:mrow> <d:mprescripts/> <d:none/> <d:mrow> <d:mn>3</d:mn> </d:mrow> </d:mmultiscripts> </d:mrow> </d:math> Rydberg levels in helium has been observed in low-temperature ( <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mo>∼</g:mo> <g:mn>80</g:mn> <g:mtext> </g:mtext> <g:mtext> </g:mtext> <g:mi>mK</g:mi> </g:math> ) collisions with ammonia molecules that undergo inversion transitions in their X <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:mrow> <i:mmultiscripts> <i:mrow> <i:msub> <i:mrow> <i:mi mathvariant="normal">A</i:mi> </i:mrow> <i:mrow> <i:mn>1</i:mn> </i:mrow> </i:msub> </i:mrow> <i:mprescripts/> <i:none/> <i:mrow> <i:mn>1</i:mn> </i:mrow> </i:mmultiscripts> </i:mrow> </i:math> ground electronic state. This hybrid Rydberg-atom–polar-molecule resonant energy transfer represents a monopole-dipole energy exchange reaction that necessarily requires spatial overlap of the Rydberg-electron and molecular wave functions. Calculations that account explicitly for the charge-dipole interaction between the Rydberg electron and the molecule provide a quantitative explanation of the observations. Total parity is conserved in the reaction through the mixing of collisional angular momentum in the atom-molecule complex. This work opens opportunities to expand the toolbox for quantum science with charge-dipole-mediated energy exchange in hybrid atom–polar-molecule platforms.