Quadrupole-induced electrical control of a single 123-Sb nucleus

The 123-Sb atom is a group-V element with a nuclear spin quantum number of 7/2, resulting in an 8-dimensional Hilbert space. This atom can be implanted in a silicon Metal-Oxide-Semiconductor structure, and its quantum state can be controlled using the same infrastructure that has been proven to yield high-fidelity control and single-shot readout on the 31-P donor. The key difference in 123-Sb is that the nucleus possesses a quadrupole moment, which introduces a quadratic term in the spin Hamiltonian in the presence of an electric field gradient, arising when the atom is placed in a strained silicon crystal. The quadrupole interaction enables the electric driving of nuclear transitions of an ionized donor, allowing us to obtain a spectrum of both single (Δm=1) and double (Δm=2) quantum transitions, as well as measurements of the coherence times between different nuclear eigenstates.

Upon addition of a strong magnetic drive, the 123-Sb nucleus is a single-atom quantum system that accurately maps a classically chaotic one: the driven nonlinear top. Therefore, we can engineer a highly controllable, individual quantum system that enables an experimental study of the emergence of chaos and the quantum-to-classical crossover