4,112 research outputs found
Properties of implanted and CVD incorporated nitrogen-vacancy centers: preferential charge state and preferential orientation
The combination of the long electron state spin coherence time and the optical coupling of the ground electronic states to an excited state manifold makes the nitrogen-vacancy (NV) center in diamond an attractive candidate for quantum information processing. To date the best spin and optical properties have been found in centers deep within the diamond crystal. For useful devices it will be necessary to engineer NVs with similar properties close to the diamond surface. We report on properties including charge state control and preferential orientation for near surface NVs formed either in CVD growth or through implantation and annealing
Observation of the dynamic Jahn-Teller effect in the excited states of nitrogen-vacancy centers in diamond
The optical transition linewidth and emission polarization of single
nitrogen-vacancy (NV) centers are measured from 5 K to room temperature.
Inter-excited state population relaxation is shown to broaden the zero-phonon
line and both the relaxation and linewidth are found to follow a T^5 dependence
for T up to 100 K. This dependence indicates that the dynamic Jahn-Teller
effect is the dominant dephasing mechanism for the NV optical transitions at
low temperatures
Low-temperature tapered-fiber probing of diamond NV ensembles coupled to GaP microcavities
In this work we present a platform for testing the device performance of a
cavity-emitter system, using an ensemble of emitters and a tapered optical
fiber. This method provides high-contrast spectra of the cavity modes,
selective detection of emitters coupled to the cavity, and an estimate of the
device performance in the single- emitter case. Using nitrogen-vacancy (NV)
centers in diamond and a GaP optical microcavity, we are able to tune the
cavity onto the NV resonance at 10 K, couple the cavity-coupled emission to a
tapered fiber, and measure the fiber-coupled NV spontaneous emission decay.
Theoretically we show that the fiber-coupled average Purcell factor is 2-3
times greater than that of free-space collection; although due to ensemble
averaging it is still a factor of 3 less than the Purcell factor of a single,
ideally placed center.Comment: 15 pages, 6 figure
Monitoring SO2 emission at the Soufriere Hills Volcano: implications for changes in erruptive conditions
FLWINinfo:eu-repo/semantics/publishe
Magma production and growth of the lava dome of the Soufriere Hills Volcano, Montserrat, West Indies: November 1995 to November 1997
M-Dwarf Fast Rotators and the Detection of Relatively Young Multiple M-Star Systems
We have searched the Kepler light curves of ~3900 M-star targets for evidence
of periodicities that indicate, by means of the effects of starspots, rapid
stellar rotation. Several analysis techniques, including Fourier transforms,
inspection of folded light curves, 'sonograms', and phase tracking of
individual modulation cycles, were applied in order to distinguish the
periodicities due to rapid rotation from those due to stellar pulsations,
eclipsing binaries, or transiting planets. We find 178 Kepler M-star targets
with rotation periods, P_rot, of < 2 days, and 110 with P_rot < 1 day. Some 30
of the 178 systems exhibit two or more independent short periods within the
same Kepler photometric aperture, while several have three or more short
periods. Adaptive optics imaging and modeling of the Kepler pixel response
function for a subset of our sample support the conclusion that the targets
with multiple periods are highly likely to be relatively young physical binary,
triple, and even quadruple M star systems. We explore in detail the one object
with four incommensurate periods all less than 1.2 days, and show that two of
the periods arise from one of a close pair of stars, while the other two arise
from the second star, which itself is probably a visual binary. If most of
these M-star systems with multiple periods turn out to be bound M stars, this
could prove a valuable way of discovering young hierarchical M-star systems;
the same approach may also be applicable to G and K stars. The ~5% occurrence
rate of rapid rotation among the ~3900 M star targets is consistent with spin
evolution models that include an initial contraction phase followed by magnetic
braking, wherein a typical M star can spend several hundred Myr before spinning
down to periods longer than 2 days.Comment: 17 pages, 12 figures, 2 tables; accepted for publication in The
Astrophysical Journa
Transport processes of particles in dilute suspensions in turbulent water flow–phase I
Modifications to an existing experimental system have been made and have been demonstrated to provide the required resolution and variable parameterization necessary for a detailed study of dilute particle suspensions in a turbulent water flow. These modifications together with the reasons for their necessity are discussed. Linearization of non-Stokesian drag has been accomplished through the introduction of a diagonal tensor into the Stokes drag force equation. It was found that non-Stokesian effects tend to be of minor importance in the response of water borne particles.U.S. Department of the InteriorU.S. Geological SurveyOpe
Exactly solvable models of supersymmetric quantum mechanics and connection to spectrum generating algebra
For nonrelativistic Hamiltonians which are shape invariant, analytic
expressions for the eigenvalues and eigenvectors can be derived using the well
known method of supersymmetric quantum mechanics. Most of these Hamiltonians
also possess spectrum generating algebras and are hence solvable by an
independent group theoretic method. In this paper, we demonstrate the
equivalence of the two methods of solution by developing an algebraic framework
for shape invariant Hamiltonians with a general change of parameters, which
involves nonlinear extensions of Lie algebras.Comment: 12 pages, 2 figure
Shape Invariance and Its Connection to Potential Algebra
Exactly solvable potentials of nonrelativistic quantum mechanics are known to
be shape invariant. For these potentials, eigenvalues and eigenvectors can be
derived using well known methods of supersymmetric quantum mechanics. The
majority of these potentials have also been shown to possess a potential
algebra, and hence are also solvable by group theoretical techniques. In this
paper, for a subset of solvable problems, we establish a connection between the
two methods and show that they are indeed equivalent.Comment: Latex File, 10 pages, One figure available on request. Appeared in
the proceedings of the workshop on "Supersymmetric Quantum Mechanics and
Integrable Models" held at University of Illinois, June 12-14, 1997; Ed. H.
Aratyn et a
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