Quantum dynamics in single spin measurement

Quantum state manipulation has become a fascinating perspective of modern physics. With concepts developed in atomic and molecular physics the field has been further stimulated by the possibility of quantum computation. For this purpose a number of individual two-state quantum systems (qubits) should be manipulated in a controlled way. Several physical realizations of qubits have been considered in recent years, but nano-electronic devices appear particularly promising because they can be embedded in circuit and scaled up to large number of qubits. In addition to manipulation, single qubit measurement is an important and delicate question. For instance, a force resolution of attonewtons is required to detect qubits represented by single spins [1]. Nowadays, magnetic resonance force microscopy (MRFM) is striving for this ultimate goal [2]. The use of cantilevers to detect small forces is at the heart of force microscopy in all its various forms [3]. Therefore, it is one of the most promising techniques to also achieve single spin detection.