19 research outputs found
Magnetic criticality-enhanced hybrid nanodiamond-thermometer under ambient conditions
Nitrogen vacancy (NV) centres in diamond are attractive as quantum sensors
owing to their superb coherence under ambient conditions. However, the NV
centre spin resonances are relatively insensitive to some important parameters
such as temperature. Here we design and experimentally demonstrate a hybrid
nano-thermometer composed of NV centres and a magnetic nanoparticle (MNP), in
which the temperature sensitivity is enhanced by the critical magnetization of
the MNP near the ferromagnetic-paramagnetic transition temperature. The
temperature susceptibility of the NV center spin resonance reached 14 MHz/K,
enhanced from the value without the MNP by two orders of magnitude. The
sensitivity of a hybrid nano-thermometer composed of a Cu_{1-x}Ni_{x} MNP and a
nanodiamond was measured to be 11 mK/Hz^{1/2} under ambient conditions. With
such high-sensitivity, we monitored nanometer-scale temperature variation of
0.3 degree with a time resolution of 60 msec. This hybrid nano-thermometer
provides a novel approach to studying a broad range of thermal processes at
nanoscales such as nano-plasmonics, sub-cellular heat-stimulated processes,
thermodynamics of nanostructures, and thermal remanent magnetization of
nanoparticles.Comment: 21 pages, 6 figure
Readout and Control of a Single Nuclear Spin with a Metastable Electron Spin Ancilla
Electron and nuclear spins associated with point defects in insulators are promising systems for solid-state quantum technology1, 2, 3. The electron spin is usually used for readout and addressing, and nuclear spins are used as exquisite quantum bits4, 5 and memory systems3, 6. With these systems, single-shot readout of single nuclear spins5, 7 as well as entanglement4, 8, 9, aided by the electron spin, have been shown. Although the electron spin in this example is essential for readout, it usually limits the nuclear spin coherence10, leading to a quest for defects with spin-free ground states9, 11. Here, we isolate a hitherto unidentified defect in diamond and use it at room temperature to demonstrate optical spin polarization and readout with exceptionally high contrast (up to 45%), coherent manipulation of an individual excited triplet state spin, and coherent nuclear spin manipulation using the triplet electron spin as a metastable ancilla. We demonstrate nuclear magnetic resonance and Rabi oscillations of the uncoupled nuclear spin in the spin-free electronic ground state. Our study demonstrates that nuclei coupled to single metastable electron spins are useful quantum systems with long memory times, in spite of electronic relaxation processes.Engineering and Applied Science
Sensing remote nuclear spins
Sensing single nuclear spins is a central challenge in magnetic resonance
based imaging techniques. Although different methods and especially diamond
defect based sensing and imaging techniques in principle have shown sufficient
sensitivity, signals from single nuclear spins are usually too weak to be
distinguished from background noise. Here, we present the detection and
identification of remote single C-13 nuclear spins embedded in nuclear spin
baths surrounding a single electron spins of a nitrogen-vacancy centre in
diamond. With dynamical decoupling control of the centre electron spin, the
weak magnetic field ~10 nT from a single nuclear spin located ~3 nm from the
centre with hyperfine coupling as weak as ~500 Hz is amplified and detected.
The quantum nature of the coupling is confirmed and precise position and the
vector components of the nuclear field are determined. Given the distance over
which nuclear magnetic fields can be detected the technique marks a firm step
towards imaging, detecting and controlling nuclear spin species external to the
diamond sensor