On the decoherence rates of single surface-state-electrons on helium

Single electrons bound to the surface of liquid helium at 10 mK serve as a promising quantum computing candidate due to their predicted low decoherence rates and the natural scalability of platform. Particular attention has been given to the orbital states of the electrons, as coupling of the in-plane electric dipole moment of the electron to a microwave resonator provides a simple high-fidelity readout mechanism. The fidelity of the readout is limited by the ratio of the coupling strength to i)the microwave cavity loss and ii)the electron decoherence rate. While low loss microwave cavities are readily fabricated, the current decoherence rates have remained too large compared to the coupling strength to achieve high fidelity readout of the qubit states. Here we explore the decoherence rate of the electron in two different temperature regimes: i) 10 mK, and ii) 1 K. We focus primarily on i)the dephasing rate due to the interaction with low-energy ripplons, and ii)the decay rate due to the interaction scattering off of helium vapor atoms. We compare the decoherence rates to our recent experiments. These results serve as a guide to improving the current electrons on helium decoherence rates and a potential route to experiments at higher temperatures.