45 research outputs found
All-optical hyperpolarization of electron and nuclear spins in diamond
Low thermal polarization of nuclear spins is a primary sensitivity limitation
for nuclear magnetic resonance. Here we demonstrate optically pumped
(microwave-free) nuclear spin polarization of and
in -doped diamond.
polarization enhancements up to above thermal equilibrium are observed
in the paramagnetic system . Nuclear spin polarization is
shown to diffuse to bulk with NMR enhancements of at
room temperature and at , enabling a route to
microwave-free high-sensitivity NMR study of biological samples in ambient
conditions.Comment: 5 pages, 5 figure
Theoretical model of the dynamic spin polarization of nuclei coupled to paramagnetic point defects in diamond and silicon carbide
Dynamic nuclear spin polarization (DNP) mediated by paramagnetic point
defects in semiconductors is a key resource for both initializing nuclear
quantum memories and producing nuclear hyperpolarization. DNP is therefore an
important process in the field of quantum-information processing,
sensitivity-enhanced nuclear magnetic resonance, and nuclear-spin-based
spintronics. DNP based on optical pumping of point defects has been
demonstrated by using the electron spin of nitrogen-vacancy (NV) center in
diamond, and more recently, by using divacancy and related defect spins in
hexagonal silicon carbide (SiC). Here, we describe a general model for these
optical DNP processes that allows the effects of many microscopic processes to
be integrated. Applying this theory, we gain a deeper insight into dynamic
nuclear spin polarization and the physics of diamond and SiC defects. Our
results are in good agreement with experimental observations and provide a
detailed and unified understanding. In particular, our findings show that the
defects' electron spin coherence times and excited state lifetimes are crucial
factors in the entire DNP process
The Principles of Social Order. Selected Essays of Lon L. Fuller, edited With an introduction by Kenneth I. Winston
The electron spins of semiconductor defects can have complex interactions with their host, particularly in polar materials like SiC where electrical and mechanical variables are intertwined. By combining pulsed spin resonance with ab initio simulations, we show that spin-spin interactions in 4H-SiC neutral divacancies give rise to spin states with a strong Stark effect, sub-10(-6) strain sensitivity, and highly spin-dependent photoluminescence with intensity contrasts of 15%-36%. These results establish SiC color centers as compelling systems for sensing nanoscale electric and strain fields
High fidelity bi-directional nuclear qubit initialization in SiC
Dynamic nuclear polarization (DNP) is an attractive method for initializing
nuclear spins that are strongly coupled to optically active electron spins
because it functions at room temperature and does not require strong magnetic
fields. In this Letter, we demonstrate that DNP, with near-unity polarization
efficiency, can be generally realized in weakly coupled hybrid registers, and
furthermore that the nuclear spin polarization can be completely reversed with
only sub-Gauss magnetic field variations. This mechanism offers new avenues for
DNP-based sensors and radio-frequency free control of nuclear qubits
Optical polarization of nuclear spins in silicon carbide
We demonstrate optically pumped dynamic nuclear polarization of 29-Si nuclear
spins that are strongly coupled to paramagnetic color centers in 4H- and
6H-SiC. The 99 +/- 1% degree of polarization at room temperature corresponds to
an effective nuclear temperature of 5 microKelvin. By combining ab initio
theory with the experimental identification of the color centers' optically
excited states, we quantitatively model how the polarization derives from
hyperfine-mediated level anticrossings. These results lay a foundation for
SiC-based quantum memories, nuclear gyroscopes, and hyperpolarized probes for
magnetic resonance imaging.Comment: 21 pages including supplementary information; four figures in main
text and one tabl
Isolated spin qubits in SiC with a high-fidelity infrared spin-to-photon interface
The divacancies in SiC are a family of paramagnetic defects that show promise
for quantum communication technologies due to their long-lived electron spin
coherence and their optical addressability at near-telecom wavelengths.
Nonetheless, a mechanism for high-fidelity spin-to-photon conversion, which is
a crucial prerequisite for such technologies, has not yet been demonstrated.
Here we demonstrate a high-fidelity spin-to-photon interface in isolated
divacancies in epitaxial films of 3C-SiC and 4H-SiC. Our data show that
divacancies in 4H-SiC have minimal undesirable spin-mixing, and that the
optical linewidths in our current sample are already similar to those of recent
remote entanglement demonstrations in other systems. Moreover, we find that
3C-SiC divacancies have millisecond Hahn-echo spin coherence time, which is
among the longest measured in a naturally isotopic solid. The presence of
defects with these properties in a commercial semiconductor that can be
heteroepitaxially grown as a thin film on shows promise for future quantum
networks based on SiC defects.Comment: 26 pages, 4 figure
Electrically and mechanically tunable electron spins in silicon carbide color centers
The electron spins of semiconductor defects can have complex interactions
with their host, particularly in polar materials like SiC where electrical and
mechanical variables are intertwined. By combining pulsed spin resonance with
ab-initio simulations, we show that spin-spin interactions within SiC neutral
divacancies give rise to spin states with an enhanced Stark effect, sub-10**-6
strain sensitivity, and highly spin-dependent photoluminescence with intensity
contrasts of 15-36%. These results establish SiC color centers as compelling
systems for sensing nanoscale fields.Comment: 10 pages, 4 figures, 1 tabl
Theoretical model of dynamic spin polarization of nuclei coupled to paramagnetic point defects in diamond and silicon carbide
Dynamic nuclear spin polarization (DNP) mediated by paramagnetic point defects in semiconductors is a key resource for both initializing nuclear quantum memories and producing nuclear hyperpolarization. DNP is therefore an important process in the field of quantum-information processing, sensitivity-enhanced nuclear magnetic resonance, and nuclear-spin-based spintronics. DNP based on optical pumping of point defects has been demonstrated by using the electron spin of nitrogen-vacancy (NV) center in diamond, and more recently, by using divacancy and related defect spins in hexagonal silicon carbide (SiC). Here, we describe a general model for these optical DNP processes that allows the effects of many microscopic processes to be integrated. Applying this theory, we gain a deeper insight into dynamic nuclear spin polarization and the physics of diamond and SiC defects. Our results are in good agreement with experimental observations and provide a detailed and unified understanding. In particular, our findings show that the defects electron spin coherence times and excited state lifetimes are crucial factors in the entire DNP process
Optical Polarization of Nuclear Spins in Silicon Carbide
We demonstrate optically pumped dynamic nuclear polarization of 29Si nuclear spins that are strongly coupled to paramagnetic color centers in 4H- and 6H-SiC. The 99 ± 1% degree of polarization at room temperature corresponds to an effective nuclear temperature of 5 K. By combining ab initio theory with the experimental identification of the color centers’ optically excited states, we quantitatively model how the polarization derives from hyperfine-mediated level anticrossings. These results lay a foundation for SiC-based quantum memories, nuclear gyroscopes, and hyperpolarized probes for magnetic resonance imaging