Measurement of Heating Rates in a Microscopic Surface-Electrode Ion Trap

We report measurement of heating rates of ^40Ca^+ ions confined in our home-made microscopic surface-electrode trap by a Doppler recooling method. The ions are trapped with approximately 800 μm above the surface, and are subjected to heating due to various noises in the trap. There are 3–5 ions involved to measure the heating rates precisely and efficiently. We show the heating rates in variance with the number and the position of the ions as well as the radio-frequency power, which are helpful for understanding the trap imperfection.