It is pointed out that there are some fundamental difficulties with the frequently used continuous-time formalism of the spin-coherent-state path integral. They arise already in a single-spin system and at the level of the ”classical action” not to speak of fluctuations around the ”classical path”. Similar difficulties turn out to be present in the case of the (boson-)coherentstate path integra...

Solid state Nuclear Magnetic Resonance (NMR) allows us to explore a large coherent spin system and provides an ideal test-bed for studying strongly interacting multiplespin system in a large Hilbert space. In this thesis, we experimentally investigate the spin dynamics in a rigid lattice of dipolarly coupled nuclear spins using multiple quantum NMR spectroscopy. Encoding multiple quantum cohere...

Precise coherent control of the individual electronic spins associated with atomlike impurities in the solid state is essential for applications in quantum information processing and quantum metrology. We demonstrate all-optical initialization, fast coherent manipulation, and readout of the electronic spin of the negatively charged nitrogenvacancy (NV−) center in diamond at T ∼ 7 K. We then pre...

We present detailed calculations of low-energy spin dynamics in the " ferric wheel " systems Na:Fe6 and Cs:Fe8 in a magnetic field. We compute by exact diagonalisation the low-energy spectra and matrix elements for total-spin and Néel-vector components, and thus the time-dependent correlation functions of these operators. Comparison of our results with the semiclassical theory of coherent quant...

Many common magnetic resonance imaging sequences are classified either as spin echo or gradient echo techniques. Generally, a gradient echo occurs when spins are coherent regardless of their position within the sample. This occurs whenever the net gradient area since a previous echo is zero. In a spin echo, spins are coherent regardless of their resonance frequency [1]. Here we will focus on gr...

We propose and analyze a new approach for quantum state transfer between remote spin qubits. Specifically, we demonstrate that coherent quantum coupling between remote qubits can be achieved via certain classes of random, unpolarized (infinite temperature) spin chains. Our method is robust to coupling-strength disorder and does not require manipulation or control over individual spins. In princ...

We examine the results of the paper “Precision metrology using weak measurements” (Zhang et al. arXiv:1310.5302, 2013) from a quantum state discrimination point of view. The Heisenberg scaling of the photon number for the precision of the interaction parameter between coherent light and a spin one-half particle (or pseudospin) has a simple interpretation in terms of the interaction rotating the...