6 research outputs found
Clock transition by continuous dynamical decoupling of a three-level system
We present a novel continuous dynamical decoupling scheme for the
construction of a robust qubit in a three-level system. By means of a clock
transition adjustment, we first show how robustness to environmental noise is
achieved, while eliminating drive-noise, to first-order. We demonstrate this
scheme with the spin sub-levels of the NV-centre's electronic ground state. By
applying drive fields with moderate Rabi frequencies, the drive noise is
eliminated and an improvement of 2 orders of magnitude in the coherence time is
obtained compared to the pure dephasing time. We then show how the clock
transition adjustment can be tuned to eliminate also the second-order effect of
the environmental noise with moderate drive fields. A further improvement of
more than 1 order of magnitude in the coherence time is expected and confirmed
by simulations. Hence, our scheme prolongs the coherence time towards the
lifetime-limit using a relatively simple experimental setup.Comment: 7 pages, 5 figure
Narrow-bandwidth sensing of high-frequency fields with continuous dynamical decoupling
State-of-the-art methods for sensing weak AC fields are only efficient in the low frequency domain. Here, Stark et al. demonstrate a sensing scheme that is capable of probing high frequencies through continuous dynamical coupling by applying it to a nitrogen-vacancy centre in diamond
Optically induced dynamic nuclear spin polarisation in diamond
The sensitivity of Magnetic Resonance Imaging (MRI) depends strongly on
nuclear spin polarisation and, motivated by this observation, dynamical nuclear
spin polarisation has recently been applied to enhance MRI protocols
(Kurhanewicz, J., et al., Neoplasia 13, 81 (2011)). Nuclear spins associated
with the 13 C carbon isotope (nuclear spin I = 1/2) in diamond possess uniquely
long spin lattice relaxation times (Reynhardt, E.C. and G.L. High, Prog. in
Nuc. Mag. Res. Sp. 38, 37 (2011)) If they are present in diamond nanocrystals,
especially when strongly polarised, they form a promising contrast agent for
MRI. Current schemes for achieving nuclear polarisation, however, require
cryogenic temperatures. Here we demonstrate an efficient scheme that realises
optically induced 13 C nuclear spin hyperpolarisation in diamond at room
temperature and low ambient magnetic field. Optical pumping of a
Nitrogen-Vacancy (NV) centre creates a continuously renewable electron spin
polarisation which can be transferred to surrounding 13 C nuclear spins.
Importantly for future applications we also realise polarisation protocols that
are robust against an unknown misalignment between magnetic field and crystal
axis.Comment: This is the revision submitted to NJ