82 research outputs found
Analysis of atomic magnetometry using metasurface optics for balanced polarimetry
Atomic magnetometry is one of the most sensitive field-measurement techniques
for biological, geo-surveying, and navigation applications. An essential
process in atomic magnetometry is measurement of optical polarization rotation
of a near-resonant beam due to its interaction with atomic spins under an
external magnetic field. In this work, we present the design and analysis of a
silicon-metasurface-based polarization beam splitter that have been tailored
for operation in a rubidium magnetometer. The metasurface polarization beam
splitter operates at a wavelength of 795 nm and has a transmission efficiency >
83% and a polarization extinction ratio > 20 dB. We show that these performance
specifications are compatible with magnetometer operation in miniaturized vapor
cells with subpicotesla-level sensitivity and discuss the prospect of realizing
compact, high-sensitivity atomic magnetometers with nanophotonic component
integration
Cluster-state creation in liquid-state NMR
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.Includes bibliographical references (p. 57-60).The subject of this thesis is devoted to a class of multiparticle entangled states known as the cluster-states. In particular, we focused on a system of four spins and studied the entanglement properties of a four-qubit cluster-state, using a set of entanglement measures for quantifying multipartite entanglement. We then experimentally prepared the linear cluster-state in a liquid NMR sample of crotonic acid, by applying a set of pulses generated by the Gradient Ascent Pulse Engineering (GRAPE) algorithm on a temporally averaged pseudo-pure state of four carbon spins. While our spectral results were consistent with the creation of a linear cluster-state, the reconstruction of the experimental density matrix via a full state tomography of the system revealed additional challenges in the detection of certain desired spin terms. These problems must be overcome before the system could be studied quantitatively.by Jennifer T. Choy.S.B
Depth dependence of the radiative lifetime of shallow color centers in single crystalline diamond
Optically active defects in diamond are widely used as bright single-photon
sources for quantum sensing, computing, and communication. For many
applications, it is useful to place the emitter close to the diamond surface,
where the radiative properties of the emitter are strongly modified by its
dielectric environment. It is well-known that the radiative power from an
electric dipole decreases as the emitter approaches an interface with a
lower-index dielectric, leading to an increase in the radiative lifetime. For
emitters in crystalline solids, modeling of this effect needs to take into
account the crystal orientation and direction of the surface cut, which can
greatly impact the emission characteristics. In this paper, we provide a
framework for analyzing the emission rates of shallow (<100 nm) defects, in
which optical transitions are derived from electric dipoles in a plane
perpendicular to their spin axis. We present our calculations for the
depth-dependent radiative lifetime for color centers in (100)-, (110)-, and
(111)-cut diamond, which can be extended to other vacancy defects in diamond
Single Color Centers Implanted in Diamond Nanostructures
The development of materials processing techniques for optical diamond
nanostructures containing a single color center is an important problem in
quantum science and technology. In this work, we present the combination of ion
implantation and top-down diamond nanofabrication in two scenarios: diamond
nanopillars and diamond nanowires. The first device consists of a 'shallow'
implant (~20nm) to generate Nitrogen-vacancy (NV) color centers near the top
surface of the diamond crystal. Individual NV centers are then isolated
mechanically by dry etching a regular array of nanopillars in the diamond
surface. Photon anti-bunching measurements indicate that a high yield (>10%) of
the devices contain a single NV center. The second device demonstrates 'deep'
(~1\mu m) implantation of individual NV centers into pre-fabricated diamond
nanowire. The high single photon flux of the nanowire geometry, combined with
the low background fluorescence of the ultrapure diamond, allows us to sustain
strong photon anti-bunching even at high pump powers.Comment: 20 pages, 7 figure
Plasmonic resonators for enhanced diamond NV- center single photon sources
We propose a novel source of non-classical light consisting of plasmonic
aperture with single-crystal diamond containing a single Nitrogen-Vacancy (NV)
color center. Theoretical calculations of optimal structures show that these
devices can simultaneously enhance optical pumping by a factor of 7,
spontaneous emission rates by Fp ~ 50 (Purcell factor), and offer collection
efficiencies up to 40%. These excitation and collection enhancements occur over
a broad range of wavelengths (~30nm), and are independently tunable with device
geometry, across the excitation (~530nm) and emission (~600-800nm) spectrum of
the NV center. Implementing this system with top-down techniques in bulk
diamond crystals will provide a scalable architecture for a myriad of diamond
NV center applications.Comment: 9 pages, 7 figure
Integrated TiO2 resonators for visible photonics
We demonstrate waveguide-coupled titanium dioxide (TiO2) racetrack resonators
with loaded quality factors of 2x10^4 for the visible wavelengths. The
structures were fabricated in sputtered TiO2 thin films on oxidized silicon
substrates using standard top-down nanofabrication techniques, and passively
probed in transmission measurements using a tunable red laser. Devices based on
this material could serve as integrated optical elements as well as passive
platforms for coupling to visible quantum emitters.Comment: 4 pages, 3 figure
Effects of molecular contamination and sp carbon on oxidation of (100) single-crystal diamond surfaces
The efficacy of oxygen (O) surface terminations of specific moieties and
densities on diamond depends on factors such as crystallinity, roughness, and
crystal orientation. Given the wide breadth of diamond-like materials and
O-termination techniques, it can be difficult to discern which method would
yield the highest and most consistent O coverage on a particular subset of
diamond. We first review the relevant physical parameters for O-terminating
single-crystalline diamond (SCD) surfaces and summarize prior oxidation work on
(100) SCD. We then report on our experimental study on X-ray Photoelectron
Spectroscopy (XPS) characterization of (100) diamond surfaces treated with
oxidation methods that include wet chemical oxidation, photochemical oxidation
with UV illumination, and steam oxidation using atomic layer deposition. We
describe a rigorous XPS peak-fitting procedure for measuring the
functionalization of O-terminated samples and recommend that the reporting of
peak energy positions, line shapes, and full-width-half-maximum values of the
individual components, along with the residuals, are important for evaluating
the quality of the peak fit. Two chemical parameters on the surface, sp C
and molecular contaminants, are also crucial towards interpreting the O
coverage on the diamond surface and may account for the inconsistency in prior
reported values in literature
- …