Feasibility study on ground-state cooling and single-phonon readout of trapped electrons using hybrid quantum systems

TL;DR

This study explores methods for ground-state cooling and single-phonon readout of trapped electrons using hybrid quantum systems, advancing quantum control techniques for electron-based qubits.

Contribution

It proposes and analyzes feasible schemes for ground-state cooling and phonon detection of trapped electrons in hybrid quantum systems, a novel approach in the field.

Findings

Ground-state cooling of trapped electrons is feasible with proposed methods.

Single-phonon readout of the motional state is achievable.

Hybrid systems enable precise control of electron motional states.

Abstract

Qubits of long coherence time and fast quantum operations are long-sought objectives towards the realization of high-fidelity quantum operations and their applications to the quantum technologies. An electron levitated in a vacuum by a Paul trap is expected to be a good candidate, for its light mass and hence the high secular frequency which allows for the faster gate operations than those in trapped ions. Controlling the motional state of the trapped electron is a crucial issue, for it mediates an interaction between electron spins, intrinsic qubits embedded in electrons, and its decoherence results in degraded fidelity of two-qubit gates. In addition, an efficient readout of the motional state is important, regarding the possibility of detecting spin state by using it. Despite of such an importance, how to achieve the motional ground state and how to efficiently detect it are not reported so far. Here we propose methods addressing these issues by utilizing hybrid quantum systems involving electron-superconducting circuit and electron-ion coupled systems and analyze the feasibility of our schemes. In both systems, we show that the ground-state cooling and the single-phonon readout of the motional state of the trapped electron are possible. Our work shed light on the way to precisely control the motional states of the trapped electrons, that provides an interesting playground for the development of quantum technologies.