The spectrum of water can be considered as the juxtaposition of the spectra of two molecules, with different total nuclear spin: ortho-H2O, and para-H2O. No transitions have ever been observed between the two different nuclear-spin isotopomers. The interconversion time is unknown and it is widely assumed that interconversion is forbidden without some other intervention. However, weak nuclear sp...

Dynamic nuclear polarization, which transfers the spin polarization of electrons to nuclei, is routinely applied to enhance the sensitivity of nuclear magnetic resonance. This method is particularly useful when spin hyperpolarization can be produced and controlled optically or electrically. Here we show complete polarization of nuclei located near optically polarized nitrogen-vacancy centres in...

2 Relativistic theory of NMR shieldings and spin-spin coupling constants 3 2.1 Relativity in quantum chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Nuclear shieldings and spin-spin couplings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3 Computational methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....

The nature of the nano-scale environment presents a major challenge for solid-state implementation of spin-based qubits. In this work, a single electron spin in an optically pumped nanometer-sized III-V semiconductor quantum dot is used to control a macroscopic nuclear spin of several thousand nuclei, freezing its decay and leading to spin life-times exceeding 100 seconds at low temperatures. F...

Topological phase transitions can occur in the dissipative dynamics of a quantum system when the ratio of matrix elements for competing transport channels is varied. Here we establish a relation between such behavior in a class of non-Hermitian quantum walk problems M. S. Rudner and L. S. Levitov, Phys. Rev. Lett. 102, 065703 2009 and nuclear spin pumping in double quantum dots, which is mediat...

We determine the polarization of the bulk C nuclear-spin system in diamond produced by interaction with optically oriented nitrogen vacancy !NV" defect centers. C nuclei are polarized into the higher-energy Zeeman state with a bulk-average polarization up to 5.2%, although local polarization may be higher. The kinetics of polarization are temperature independent and occur within 5 min. Fluctuat...

Pulsed electron paramagnetic resonance spectroscopy of the photoexcited, metastable triplet state of the oxygen-vacancy center in silicon reveals that the lifetime of the m(s)=±1 sublevels differs significantly from that of the m(s)=0 state. We exploit this significant difference in decay rates to the ground singlet state to achieve nearly ~100% electron-spin polarization within the triplet. We...

Long coherence times are key to the performance of quantum bits (qubits). Here, we experimentally and theoretically show that the Hahn-echo coherence time of electron spins associated with divacancy defects in 4H-SiC reaches 1.3 ms, one of the longest Hahn-echo coherence times of an electron spin in a naturally isotopic crystal. Using a first-principles microscopic quantum-bath model, we find t...