Photoionization of Rydberg atoms in optical lattices

Abstract

We develop a formalism for photoionization (PI) and potential energy curves (PECs) of Rydberg atoms in ponderomotive optical lattices and apply it to examples covering several regimes of the optical-lattice depth. The effect of lattice-induced PI on Rydberg-atom lifetime ranges from noticeable to highly dominant when compared with natural decay. The PI behavior is governed by the generally rapid decrease of the PI cross sections as a function of angular-momentum (ℓ), lattice-induced ℓ-mixing across the optical-lattice PECs, and interference of PI transition amplitudes from the lattice-mixed into free-electron states. In GHz-deep lattices, ℓ-mixing leads to a rich PEC structure, and the significant low-ℓ PI cross sections are distributed over many lattice-mixed Rydberg states. In lattices less than several tens-of-MHz deep, atoms on low-ℓ PECs are essentially ℓ-mixing-free and maintain large PI rates, while atoms on high-ℓ PECs trend towards being PI-free. Characterization of PI in GHz-deep Rydberg-atom lattices may be beneficial for optical control and quantum-state manipulation of Rydberg atoms, while data on PI in shallower lattices are potentially useful in high-precision spectroscopy and quantum-computing applications of lattice-confined Rydberg atoms.

Gauge effects in bound-bound Rydberg-transition matrix elements

“…The properties of these weak series may offer opportunities to explore gauge effects in Rydberg electricdipole transitions for fundamental investigations. The same holds for photo-ionization cross sections, which generally show larger differences between LG and VG [27,28] than bound-bound EDTMs.…”

“…For the microwave transitions considered in the present work, the EDA is naturally satisfied due to the long radiation wavelength (k • r ≪ 1). It has been shown elsewhere that the EDA even applies to electric Rydbergatom couplings in the UV wavelength range [28], where the Rydberg-atom size typically exceeds the wavelength (k • r > 1).…”

“…Being at the core of several directions in fundamental research and emerging quantum technologies [20], Rydberg transitions from low-lying states or other Rydberg atomic states require accurate calculations [21,22]. Of particular interest are electric and magnetic multipole transition matrix elements [23], static and dynamic polaizabilities [21,24], and collisional and photoionization [25][26][27][28] cross-sections. Among the former, electric-dipole transition matrix elements (EDTMs) are the most important due to their wide usage [21].…”

Long-Range Atom–Ion Rydberg Molecule: A Novel Molecular Binding Mechanism

“…As an example, we consider the wavelength of λ PI = 1064 nm for which high-power laser sources are available. According to [39], the photoionization cross-section σ PI for direct photoionization starting from Rb Rydberg P states ranges from about 1 × 10 −21 cm 2 for n = 90 to about 2 × 10 −19 cm 2 for n = 20. Consequently, when addressing, e.g., the 17P state of Rb, a laser intensity on the order of 10 5 W cm −2 is needed to obtain a photoionization rate comparable to the rate for natural radiative decay.…”

Probing ultracold gases using photoionization fine structure

“…The GLFT method permitted us to explicitly treat the Coulomb field and the electron-atom interactions within this three-body system. Apart from Rydberg molecules, this phenomenon can be observed in systems such as atoms trapped at individual lattice sites [32]. Since this fine structure is insensitive to the alignment of the polarization axis with the interatomic one, it can be observed also in weakly bound Feshbach molecules as well [33].…”