  Electron spin qubits in silicon, whether in quantum dots or in donor atoms,
have long been considered attractive qubits for the implementation of a quantum
computer due to the semiconductor vacuum character of silicon and its
compatibility with the microelectronics industry. While donor electron spins in
silicon provide extremely long coherence times and access to the nuclear spin
via the hyperfine interaction, quantum dots have the complementary advantages
of fast electrical operations, tunability and scalability. Here we present an
approach to a novel hybrid double quantum dot by coupling a donor to a
lithographically patterned artificial atom. Using gate-based rf reflectometry,
we probe the charge stability of this double quantum dot system and the
variation of quantum capacitance at the interdot charge transition. Using
microwave spectroscopy, we find a tunnel coupling of 2.7 GHz and characterise
the charge dynamics, which reveals a charge T2* of 200 ps and a relaxation time
T1 of 100 ns. Additionally, we demonstrate spin blockade at the inderdot
transition, opening up the possibility to operate this coupled system as a
singlet-triplet qubit or to transfer a coherent spin state between the quantum
dot and the donor electron and nucleus.
