Abstract: The invention relates to an improved logic device providing fast logic implementation based on the magnetic resonance of a collection of interacting or non-interacting spins or spin systems. This fast logic device can form the centerpiece of a novel spin computer or hybrid spin computer. In one implementation, the logic device includes a spin system with a sufficiently long relaxation time in a magnetic field which provides a bi-stable state. A probehead, console and receiver enable the system to access the bi-stable state using magnetic resonance excitation and detection, and field gradients permit addressing of distinct memory cells in the spin system.