Microwave Saturation of the Rydberg States of Electrons on Helium

Abstract

We present measurements of the resonant microwave excitation of Rydberg energy levels for surface-state electrons on superfluid helium. The temperature-dependent contribution to the linewidth gamma(T) agrees with theoretical predictions and is very small below 700 mK, in the ripplon scattering regime. Absorption saturation and power broadening were observed as the fraction of electrons in the first excited state was increased to 0.49, close to the thermal excitation limit of 0.5. The Rabi frequency Omega was determined as a function of microwave power. High values of the ratio Omega/gamma confirm this system as an excellent candidate for creating qubits.

Microwave absorption saturation and decay heating of surface electrons on liquid helium

“…In this case, power absorbed by electrons from the filed P A increases linear with r, or with the in-put power P in . I n th e o p p o s ite limit o f h ig h e x c itatio n rt >> 1, n n In this work we report the results of theoretical description of MW resonance of SEs on liquid helium for the conditions of the experiment [3]. Electron temperature is found from the energy balance equation.…”

“…Since the electron potential is anharmonic, it is assumed that coupling to outer levels (l > 2) is negligible, and a simple two-level model is an excellent approximation. As an important achievement in this field, observation of MW absorption saturation of Rydberg states of SEs was reported [3]. The electron decay from the excited surface level to the ground level due to scattering by vapor atoms and ripplons is a negative factor for SE qubits.…”

“…The dimensionless parameter rt could be considered as a measure of electron excitation by MW. In the simple model of cold SEs [3], for low excitation rt << 1, the fractional occupancy of the first excited level n 2 is much smaller than that of the ground level n 1 . In this case, power absorbed by electrons from the filed P A increases linear with r, or with the in-put power P in .…”

“…Therefore, surface electrons (SEs) can move freely along the interface, forming a remarkable two-dimensional (2D) electron liquid, useful for studying many-body effects in a highly correlated 2D electron gas (for a review see [2]). The recent interest in the MW resonance is evoked by experimental development of the idea of using SEs as electronic qubits (see [3] and references there in). These qubits would be controlled by the MW field whose frequency w is close to w 0 2 1…”

“…The recent interest in the MW resonance is evoked by experimental development of the idea of using SEs as electronic qubits (see [3] and references there in). These qubits would be controlled by the MW field whose frequency w is close to w 0 2 1…”