Building principle of triatomic trilobite Rydberg molecules

Abstract

We investigate triatomic molecules that consist of two ground state atoms and a highly excited Rydberg atom, bound at large internuclear distances of thousands ofÅngstroms. In the molecular state the Rydberg electron is in a superposition of high angular momentum states whose probability densities resemble the form of trilobite fossils. The associated potential energy landscape has an oscillatory shape and supports a rich variety of stable geometries with different bond angles and bond lengths. Based on an electronic structure investigation we analyze the molecular geometry systematically and develop a simple building principle that predicts the triatomic equilibrium configurations. As a representative example we focus on 87 Rb trimers correlated to the n = 30 Rydberg state. Using an exact diagonalization scheme we determine and characterize localized vibrational states in these potential minima with energy spacings on the order of 100 MHz×h.

Ultralong-range Rydberg molecules

“…A central finding from research on polyatomic ULRMs is that binding energies of s-state ULRMs are to a good approximation additive [13], i.e. integer multiples of the number of ground-state atoms, whereas binding energies of polyatomic ULRMs with angular momenta l > 0 are non-additive and involve threeand higher body forces [15,17,18,50]. Since the only experimentally confirmed polyatomic ULRMs with l > 0 are d-state trimers, it is an interesting challenge for future experiments to detect novel polyatomics with more atoms, e.g.…”

Triatomic butterfly molecules

“…Importantly, the order of these spacings differs from triatomic low-l Rydberg molecules, where the energy spacing of bending motion is typically much smaller than stretching motion [20]. It also differs from the trilobite trimer, as shown by an example in reference [23] where the spacing of bending and stretching modes is almost equal.…”

“…The studies of trilobite trimers in Refs. [16,23] found that the eigenvalues of Eq. 4 are essentially identical to those computed using the full Rydberg basis, consisting of states with finite quantum defects and multiple Rydberg manifolds.…”

“…In this article, we show that this p-wave binding mechanism can bind a second ground-state atom to the Rydberg atom, forming a triatomic butterfly molecule. Other ultra-long-range triatomic Rydberg molecules formed by the s-wave scattering interaction have been studied previously theoretically and experimentally [16][17][18][19][20][21][22][23], but a study of the butterfly trimer's full electronic and vibrational structure has not yet been attempted. We determine this structure by computing, analyzing, and interpreting the underlying threedimensional potential energy surfaces based on the Born-Oppenheimer approximation and the resulting nuclear eigenstates.…”

Ring Rydberg composites

“…With the advent of ultracold Rydberg excitations in Bose-Einstein condensates, a subfield devoted to the study of long-range Rydberg molecules, known colloquially as trilobite molecules, has developed [7][8][9]. Experiments have resolved the vibrational spectra of Rydberg dimers, trimers, and so forth, and have sparked significant theoretical interest from the perspective of many-body physics [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. At the same time, attention has shifted towards experiments which use the Rydberg atom to probe the surrounding condensate and establish a "microscopic laboratory" to study electron-atom and ion-atom scattering [25][26][27][28][29][30][31][32].…”