  Any quantum information system operates with entanglement as a resource,
which should be deterministically generated by a joint measurement known as
complete Bell state measurement (BSM). The determinism arises from a quantum
nondemolition measurement of two coupled qubits with the help of readout
ancilla, which inevitably requires extra physical qubits. We here demonstrate a
deterministic and complete BSM with only a nitrogen atom in a nitrogen-vacancy
(NV) center in diamond as a quantum memory without reliance on any carbon
isotopes by exploiting electron nitrogen (14N) double qutrits at a zero
magnetic field. The degenerate logical qubits within the subspace of qutrits on
the electron and nitrogen spins are holonomically controlled by arbitrarily
polarized microwave and radiofrequency pulses via zero field split states as
the ancilla, enabling the complete BSM deterministically. Since the system
works under an isotope free and field free environment, the demonstration paves
the way for realizing high yield, high fidelity, and high speed quantum
repeaters for long haul quantum networks and quantum interfaces for large scale
distributed quantum computers.
