229 research outputs found
Nanoscale magnetometry through quantum control of nitrogen-vacancy centres in rotationally diffusing nanodiamonds
The confluence of quantum physics and biology is driving a new generation of
quantum-based sensing and imaging technology capable of harnessing the power of
quantum effects to provide tools to understand the fundamental processes of
life. One of the most promising systems in this area is the nitrogen-vacancy
centre in diamond - a natural spin qubit which remarkably has all the right
attributes for nanoscale sensing in ambient biological conditions. Typically
the nitrogen-vacancy qubits are fixed in tightly controlled/isolated
experimental conditions. In this work quantum control principles of
nitrogen-vacancy magnetometry are developed for a randomly diffusing diamond
nanocrystal. We find that the accumulation of geometric phases, due to the
rotation of the nanodiamond plays a crucial role in the application of a
diffusing nanodiamond as a bio-label and magnetometer. Specifically, we show
that a freely diffusing nanodiamond can offer real-time information about local
magnetic fields and its own rotational behaviour, beyond continuous optically
detected magnetic resonance monitoring, in parallel with operation as a
fluorescent biomarker.Comment: 9 pages, with 5 figure
Analytical approximation for the structure of differentially rotating barotropes
Approximate analytical formula for density distribution in differentially
rotating stars is derived. Any barotropic EOS and conservative rotation law can
be handled with use of this method for wide range of differential rotation
strength. Results are in good qualitative agreement with comparison to the
other methods. Some applications are suggested and possible improvements of the
formula are discussed.Comment: 10 pages, 13 figures, accepted for publication in Monthly Notice
Single atom-scale diamond defect allows large Aharonov-Casher phase
We propose an experiment that would produce and measure a large
Aharonov-Casher (A-C) phase in a solid-state system under macroscopic motion. A
diamond crystal is mounted on a spinning disk in the presence of a uniform
electric field. Internal magnetic states of a single NV defect, replacing
interferometer trajectories, are coherently controlled by microwave pulses. The
A-C phase shift is manifested as a relative phase, of up to 17 radians, between
components of a superposition of magnetic substates, which is two orders of
magnitude larger than that measured in any other atom-scale quantum system.Comment: 5 pages, 2 figure
Measurable quantum geometric phase from a rotating single spin
We demonstrate that the internal magnetic states of a single nitrogen-vacancy
defect, within a rotating diamond crystal, acquire geometric phases. The
geometric phase shift is manifest as a relative phase between components of a
superposition of magnetic substates. We demonstrate that under reasonable
experimental conditions a phase shift of up to four radians could be measured.
Such a measurement of the accumulation of a geometric phase, due to macroscopic
rotation, would be the first for a single atom-scale quantum system.Comment: 5 pages, 2 figures: Accepted for publication in Physical Review
Letter
The Canaanite Background of the Doctrine of the Virgin Mary
Naturally, contributions from places other than this one will be encouraged, indeed, sought. There could be no other way to promote a more wide understanding of Religion in Australia, than this. Religious Traditions journal in other words, though meant in part to be the product of a need felt among Australian "religionists", must, by dint of that very fact, take its place besides other international Journals in the field
BlinkML: Efficient Maximum Likelihood Estimation with Probabilistic Guarantees
The rising volume of datasets has made training machine learning (ML) models
a major computational cost in the enterprise. Given the iterative nature of
model and parameter tuning, many analysts use a small sample of their entire
data during their initial stage of analysis to make quick decisions (e.g., what
features or hyperparameters to use) and use the entire dataset only in later
stages (i.e., when they have converged to a specific model). This sampling,
however, is performed in an ad-hoc fashion. Most practitioners cannot precisely
capture the effect of sampling on the quality of their model, and eventually on
their decision-making process during the tuning phase. Moreover, without
systematic support for sampling operators, many optimizations and reuse
opportunities are lost.
In this paper, we introduce BlinkML, a system for fast, quality-guaranteed ML
training. BlinkML allows users to make error-computation tradeoffs: instead of
training a model on their full data (i.e., full model), BlinkML can quickly
train an approximate model with quality guarantees using a sample. The quality
guarantees ensure that, with high probability, the approximate model makes the
same predictions as the full model. BlinkML currently supports any ML model
that relies on maximum likelihood estimation (MLE), which includes Generalized
Linear Models (e.g., linear regression, logistic regression, max entropy
classifier, Poisson regression) as well as PPCA (Probabilistic Principal
Component Analysis). Our experiments show that BlinkML can speed up the
training of large-scale ML tasks by 6.26x-629x while guaranteeing the same
predictions, with 95% probability, as the full model.Comment: 22 pages, SIGMOD 201
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Timekeeping with electron spin states in diamond
Frequency standards based on atomic states, such as Rb or Cs vapors, or single-trapped ions, are the most precise measures of time. Here we propose and analyze a precision oscillator approach based upon spins in a solid-state system, in particular, the nitrogen-vacancy defect in single-crystal diamond. We show that this system can have stability approaching portable atomic standards and is readily incorporable as a chip-scale device. Using a pulsed spin-echo technique, we anticipate an Allan deviation of σy=10−7τ−1/2 limited by thermally-induced strain variations; in the absence of such thermal fluctuations, the system is limited by spin dephasing and harbors an Allan deviation nearing ∼10−12τ−1/2. Potential improvements based upon advanced diamond material processing, temperature stabilization, and nanophotonic engineering are discussed.Physic
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