A Radio-Frequency Emitter Design for the Low-Frequency Regime in Atomic Experiments

TL;DR

This paper introduces a compact RF circuit design for atomic experiments that efficiently covers a broad frequency range, enabling improved cooling and atom transfer in cold atom setups.

Contribution

The paper presents a novel RF circuit with a capacitive transformer network that enhances power delivery and impedance matching across wide frequencies in atomic experiments.

Findings

Reduced RF power for evaporative cooling from 14.7dBW to -3.5dBW.

Achieved cooling of Bose-Fermi mixture below 10 μK.

Transferred 80% of rubidium atoms in 1 ms with a 9 kHz Rabi frequency.

Abstract

Radio-frequency (RF) control is a key technique in cold atom experiments. We present a compact and efficient RF circuit based on a capacitive transformer network, where a low-frequency coil operating up to 30MHz serves as both an intrinsic inductor and a power-sharing element. The design enables high current delivery and flexible impedance matching across a wide frequency range. We integrate both broadband and narrowband RF networks into a unified configuration that overcomes the geometric constraints imposed by the metallic chamber. In evaporative cooling, the broadband network allows a reduction of the applied RF input power from 14.7dBW to -3.5dBW, owing to its non-zero coil current even at ultra-low frequencies. This feature enables the Bose-Fermi mixture to be cooled below 10{\mu}K. In a Landau-Zener protocol, the coil driven by the narrowband network transfers 80% of rubidium atoms from |F = 2,mF = 2> to |2,-2> in 1 millisecond, achieving a Rabi frequency of approximately 9 kHz at an input power of 0.1dBW.