Efficient NMR manipulation of single electron-nuclear spin registers

G. B. Furman, V. Meerovich, Vladimir Sokolovsky

Zhenyu Wang, Jorge Casanova, Martin Bodo Plenio

Methods to selectively detect and manipulate nuclear spins by single electrons of solid-state defects play a central role for quantum information processing and nanoscale nuclear magnetic resonance (NMR). However, with standard techniques, no more than eight nuclear spins have been resolved by a single defect centre. Here we develop a method that improves significantly the ability to detect, address and manipulate nuclear spins unambiguously and individually in a broad frequency band by using a nitrogen-vacancy (NV) centre as model system. On the basis of delayed entanglement control, a technique combining microwave and radio frequency fields, our method allows to selectively perform robust high-fidelity entangling gates between hardly resolved nuclear spins and the NV electron. Long-lived qubit memories can be naturally incorporated to our method for improved performance. The application of our ideas will increase the number of useful register qubits accessible to a defect centre and improve the signal of nanoscale NMR.

Hester G. Vennema, Cristina Mier, Evert W. Stolte +3 more

The nuclear spin is a prime candidate for quantum information applications due to its weak coupling to the environment and inherently long coherence times. However, this weak coupling also challenges the addressability of the nuclear spin. Here we demonstrate nuclear magnetic resonance (NMR) on a single on-surface atom using a local scanning probe. We employ an electron-nuclear double resonance measurement scheme and resolve nuclear spin transitions of a single 47Ti isotope with a nuclear spin of I = 5/2. The quadrupole interaction enables to resolve multiple NMR transitions, which are consistent with our eigenenergy calculations. Our experimental results indicate that the nuclear spin can be driven efficiently irrespective of its hybridization with the electron spin, which is required for direct control of the nuclear spin in the long-lifetime regime. This investigation of NMR on a single atom in a platform with atomic-scale control is a valuable development for other platforms deploying nuclear spins for characterization techniques or quantum information technology.

真治 松本

Alexander A. Kokin, V. A. Kokin

It is given the refinements and further development of NMR model of quantum register based on easy-axis nuclear spin-free antiferromagnet, which was presented previously in paper. The model suggests that external magnetic field is directed along the easy axis, normally to the plate surface and has a weak constant gradient along the nuclear spin chain of quantum register. In present paper it is evaluated the general expression for indirect coupling between nuclear spins due to hyperfine nuclear-electron coupling in substituted atoms and spin-wave propagation in antiferromagnet close to critical point of quantum phase transition in antiferromagnet of spin-flop type. It is given also an estimation of quantum states decoherence rate, which is caused by the interaction of nuclear spins with spin waves in antiferromagnet.

T. S. Mahesh