  Complete quantum control of a stationary quantum bit embedded in a quantum
emitter is crucial for photonic quantum information technologies. Recently, the
orbital degree of freedom in optically active semiconductor quantum dots
emerged as a promising candidate. However, the crucial ability to perform
arbitrary rotation on orbital qubits remains elusive. Here, we demonstrate
complete control of hole orbital states in a quantum dot. This is enabled by
successfully inducing stimulated Raman transitions within $\Lambda$ systems
connected via radiative Auger transitions. This new capability allows
manipulations of polar and azimuth angles of the Bloch vector, as evidenced by
Rabi oscillations and Ramsey interference, respectively. Simultaneous control
of both parameters is achieved by concurrently varying the amplitude and phase
of picosecond Raman pulses, enabling arbitrary unitary rotation of the Bloch
vector. Our results establish the orbital states in solid-state quantum
emitters as a potentially viable resource for applications in quantum
information processing and quantum communication.
