20 research outputs found
Temperature Dependent Photophysics of Single NV Centers in Diamond
We present a comprehensive study of the temperature and magnetic-field
dependent photoluminescence (PL) of individual NV centers in diamond, spanning
the temperature-range from cryogenic to ambient conditions. We directly observe
the emergence of the NV's room-temperature effective excited state structure
and provide a clear explanation for a previously poorly understood broad
quenching of NV PL at intermediate temperatures around 50 K. We develop a model
that quantitatively explains all of our findings, including the strong impact
that strain has on the temperaturedependence of the NV's PL. These results
complete our understanding of orbital averaging in the NV excited state and
have significant implications for the fundamental understanding of the NV
center and its applications in quantum sensing.Comment: 5 pages, 4 figures plus Supplementary Material. Questions and
comments are welcome. arXiv admin note: text overlap with arXiv:2105.0807
Charge stability and charge-state-based spin readout of shallow nitrogen-vacancy centers in diamond
Spin-based applications of the negatively charged nitrogen-vacancy (NV)
center in diamonds require efficient spin readout. One approach is the
spin-to-charge conversion (SCC), relying on mapping the spin states onto the
neutral (NV) and negative (NV) charge states followed by a subsequent
charge readout. With high charge-state stability, SCC enables extended
measurement times, increasing precision and minimizing noise in the readout
compared to the commonly used fluorescence detection. Nano-scale sensing
applications, however, require shallow NV centers within a few \si{\nano
\meter} distance from the surface where surface related effects might degrade
the NV charge state. In this article, we investigate the charge state
initialization and stability of single NV centers implanted \approx
\SI{5}{\nano \meter} below the surface of a flat diamond plate. We demonstrate
the SCC protocol on four shallow NV centers suitable for nano-scale sensing,
obtaining a reduced readout noise of 5--6 times the spin-projection noise
limit. We investigate the general applicability of SCC for shallow NV centers
and observe a correlation between NV charge-state stability and readout noise.
Coating the diamond with glycerol improves both charge initialization and
stability. Our results reveal the influence of the surface-related charge
environment on the NV charge properties and motivate further investigations to
functionalize the diamond surface with glycerol or other materials for
charge-state stabilization and efficient spin-state readout of shallow NV
centers suitable for nano-scale sensing.Comment: 9 pages, 5 figure
A Probabilistic Finite State Logic Machine Realized Experimentally on a Single Dopant Atom
Exploiting the potential of nanoscale devices for logic processing requires the implementation of computing functionalities departing from the conventional switching paradigm. We report on the design and the experimental realization of a probabilistic finite state machine in a single phosphorus donor atom placed in a silicon matrix electrically addressed and probed by scanning tunneling spectroscopy (STS). The single atom logic unit simulates the flow of -visitors in a maze whose topology is determined by the dynamics of the electronic transport through the states of the dopant. By considering the simplest case of a unique charge state for which three be resolved, we demonstrate an efficient solution of the following problem: in a maze of four connected rooms, what is the optimal combination of door opening rates in order to maximize the time that visitors spend in one specific chamber? The implementation takes advantage of the stochastic nature of electron tunneling, while the output remains the macroscopic current whose reading can be realized with standard techniques and does not require single electron sensitivity
Mn doped InSb studied at the atomic scale by cross-sectional scanning tunneling microscopy
We present an atomically resolved study of metal-organic vapor epitaxy grown Mn doped InSb. Both topographic and spectroscopic measurements have been performed by cross-sectional scanning tunneling microscopy (STM). The measurements on the Mn doped InSb samples show a perfect crystal structure without any precipitates and reveal that Mn acts as a shallow acceptor. The Mn concentration of the order of 1020cm3 obtained from the cross-sectional STM data compare well with the intended doping concentration. While the pair correlation function of the Mn atoms showed that their local distribution is uncorrelated beyond the STM resolution for observing individual dopants, disorder in the Mn ion location giving rise to percolation pathways is clearly noted. The amount of clustering that we see is thus as expected for a fully randomly disordered distribution of the Mn atoms and no enhanced clustering or second phase material was observed
Implementation of multivariable logic functions in parallel by electrical addressing a molecule of three dopants in Silicon
To realize low power compact logic circuits one can explore parallel operation on single nanoscale devices. An added incentive is to use multivalued (as distinct from Boolean) logic. Here we theoretically demonstrate that the computation of all the possible outputs of a multivariate, multivalued logic function can be implemented in parallel by electrical addressing of a molecule made up of three interacting dopant atoms embedded in Si. The electronic states of the dopant molecule are addressed by pulsing a gate voltage. By simulating the time evolution of the non stationary electronic density built by the gate voltage, we show that one can implement a molecular decision tree that provides in parallel all the outputs for all the inputs of the multivariate, multivalued logic function. The outputs are encoded in the populations and in the bond orders of the dopant molecule, which can be measured using a STM tip. We show that the implementation of the molecular logic tree is equivalent to a spectral function decomposition. The function that is evaluated can be field-programmed by changing the time profile of the pulsed gate voltage
Mn doped InSb studied at the atomic scale by cross-sectional scanning tunneling microscopy
We present an atomically resolved study of metal-organic vapor epitaxy grown Mn doped InSb. Both topographic and spectroscopic measurements have been performed by cross-sectional scanning tunneling microscopy (STM). The measurements on the Mn doped InSb samples show a perfect crystal structure without any precipitates and reveal that Mn acts as a shallow acceptor. The\u3cbr/\u3eMn concentration of the order of 1020cm3 obtained from the cross-sectional STM data compare well with the intended doping concentration. While the pair correlation function of the Mn atoms showed that their local distribution is uncorrelated beyond the STM resolution for observing individual dopants, disorder in the Mn ion location giving rise to percolation pathways is clearly noted. The amount of clustering that we see is thus as expected for a fully randomly disordered distribution of the Mn atoms and no enhanced clustering or second phase material was observed
Observation of the symmetry of core states of a single Fe impurity in GaAs
\u3cp\u3eWe report the direct observation of two mid-gap core d states of differing symmetry for a single Fe atom embedded in GaAs. These states are distinguished by the strength of their hybridization with the surrounding host electronic structure. The midgap state of Fe that does not hybridize via σ bonding is strongly localized to the Fe atom, whereas the other, which does, is extended and comparable in size to other acceptor states. Tight-binding calculations of these midgap states agree with the spatial structure of the measured wave functions and illustrate that such measurements can determine the degree of hybridization via π bonding of impurity d states. These single-dopant midgap states with strong d character, which are intrinsically spin-orbit-entangled, provide an opportunity for probing and manipulating local magnetism and may be of use for high-speed electrical control of single spins.\u3c/p\u3