Effects of molecular resonances on Rydberg blockade

Abstract

We study the effect of resonances associated with complex molecular interaction of Rydberg atoms on Rydberg blockade. We show that densely spaced molecular potentials between doubly excited atomic pairs become unavoidably resonant with the optical excitation at short interatomic separations. Such molecular resonances limit the coherent control of individual excitations in Rydberg blockade. As an illustration, we compute the molecular interaction potentials of Rb atoms near the 100s states asymptote to characterize such detrimental molecular resonances and determine the resonant loss rate to molecules and inhomogeneous light shifts. Techniques to avoid the undesired effect of molecular resonances are discussed.

Quantum computing with atomic qubits and Rydberg interactions: progress and challenges

“…Experimental results to date indicate worse gate fidelity and shorter coherence times for ensemble qubits than for single atom qubits [90,43,44,91]. This is not surprising due to the sensitivity of a delocalized ensemble to field gradients as well as the presence of atomic collisions and possibly molecular resonances [92]. These effects may be mitigated by patterned loading of a localized ensemble into an optical lattice to prevent short range interactions as described in [46].…”

Calculation of Rydberg interaction potentials

“…The dipole-quadrupole contribution to the interaction has recently been observed both in ultracold [94] and room-temperature [25] systems in experiments with large excitation bandwidth, while the correct prediction of macro-dimer photo-association spectra required the inclusion of terms up to octupolar order in the potential calculation [81,84]. In experiments utilizing very high principal quantum numbers n > 100 [95][96][97], state-mixing and additional molecular resonances [98] become relevant already at large interatomic distances and make non-perturbative potential calculations necessary.…”

Rydberg interaction induced enhanced excitation in thermal atomic vapor

“…In addition to this, the existence of anti-blockade between two Rydberg atoms, interacting with a zero area phase jump pulse is also reported 26 . Some recent results have also been reported to study Rydberg anti blockade in atomic 27 – 29 and molecular resonances 30 . The implementation of quantum logic gate using Rydberg anti-blockade has also recently been proposed 31 – 33 .…”