474 research outputs found
The Threat of Artificial Superintelligence
This paper discusses the development of AI and the threat posed by the theoretical achievement of artificial superintelligence. AI is becoming an increasingly significant fixture in our lives and this will only continue in the future. The development of artificial general intelligence (AGI) would quickly lead to artificial superintelligence (ASI). AI researcher Steve Omohundro’s universal drives of rational systems demonstrate why ASI could behave in ways unanticipated by its designers. A technological singularity may occur if AI is allowed to undergo uncontrolled rapid self-improvement, which could pose an extinction-level risk to the human race. Two possible safety measures, AI “boxing” and AI safety engineering, are explored, with reference to the writings of computer scientist Roman Yampolskiy and AI researcher Joshua Fox
Local readout enhancement for detuned signal-recycling interferometers
Motivated by the optical-bar scheme of Braginsky, Gorodetsky and Khalili, we
propose to add to a high power detuned signal-recycling interferometer a local
readout scheme which measures the motion of the arm-cavity front mirror. At low
frequencies this mirror moves together with the arm-cavity end mirror, under
the influence of gravitational waves. This scheme improves the low-frequency
quantum-noise-limited sensitivity of optical-spring interferometers
significantly and can be considered as a incorporation of the optical-bar
scheme into currently planned second-generation interferometers. On the other
hand it can be regarded as an extension of the optical bar scheme. Taking
compact-binary inspiral signals as an example, we illustrate how this scheme
can be used to improve the sensitivity of the planned Advanced LIGO
interferometer, in various scenarios, using a realistic classical-noise budget.
We also discuss how this scheme can be implemented in Advanced LIGO with
relative ease
Double optical spring enhancement for gravitational-wave detectors
Currently planned second-generation gravitational-wave laser interferometers such as Advanced LIGO exploit the extensively investigated signal-recycling technique. Candidate Advanced LIGO configurations are usually designed to have two resonances within the detection band, around which the sensitivity is enhanced: a stable optical resonance and an unstable optomechanical resonance—which is upshifted from the pendulum frequency due to the so-called optical-spring effect. As an alternative to a feedback control system, we propose an all-optical stabilization scheme, in which a second optical spring is employed, and the test mass is trapped by a stable ponderomotive potential well induced by two carrier light fields whose detunings have opposite signs. The double optical spring also brings additional flexibility in reshaping the noise spectral density and optimizing toward specific gravitational-wave sources. The presented scheme can be extended easily to a multi-optical-spring system that allows further optimization
An all-optical trap for a gram-scale mirror
We report on a stable optical trap suitable for a macroscopic mirror, wherein
the dynamics of the mirror are fully dominated by radiation pressure. The
technique employs two frequency-offset laser fields to simultaneously create a
stiff optical restoring force and a viscous optical damping force. We show how
these forces may be used to optically trap a free mass without introducing
thermal noise; and we demonstrate the technique experimentally with a 1 gram
mirror. The observed optical spring has an inferred Young's modulus of 1.2 TPa,
20% stiffer than diamond. The trap is intrinsically cold and reaches an
effective temperature of 0.8 K, limited by technical noise in our apparatus.Comment: Major revision. Replacement is version that appears in Phy. Rev.
Lett. 98, 150802 (2007
Naturally occurring variations in sequence length creates microRNA isoforms that differ in argonaute effector complex specificity
Creation of a quantum oscillator by classical control
As a pure quantum state is being approached via linear feedback, and the
occupation number approaches and eventually goes below unity, optimal control
becomes crucial. We obtain theoretically the optimal feedback controller that
minimizes the uncertainty for a general linear measurement process, and show
that even in the absence of classical noise, a pure quantum state is not always
achievable via feedback. For Markovian measurements, the deviation from minimum
Heisenberg Uncertainty is found to be closely related to the extent to which
the device beats the free-mass Standard Quantum Limit for force measurement. We
then specialize to optical Markovian measurements, and demonstrate that a
slight modification to the usual input-output scheme -- either injecting
frequency independent squeezed vacuum or making a homodyne detection at a
non-phase quadrature -- allows controlled states of kilogram-scale mirrors in
future LIGO interferometers to reach occupation numbers significantly below
unity.Comment: 4 pages, 2 figure
Ebbie: automated analysis and storage of small RNA cloning data using a dynamic web server
BACKGROUND: DNA sequencing is used ubiquitously: from deciphering genomes[1] to determining the primary sequence of small RNAs (smRNAs) [2-5]. The cloning of smRNAs is currently the most conventional method to determine the actual sequence of these important regulators of gene expression. Typical smRNA cloning projects involve the sequencing of hundreds to thousands of smRNA clones that are delimited at their 5' and 3' ends by fixed sequence regions. These primers result from the biochemical protocol used to isolate and convert the smRNA into clonable PCR products. Recently we completed a smRNA cloning project involving tobacco plants, where analysis was required for ~700 smRNA sequences[6]. Finding no easily accessible research tool to enter and analyze smRNA sequences we developed Ebbie to assist us with our study. RESULTS: Ebbie is a semi-automated smRNA cloning data processing algorithm, which initially searches for any substring within a DNA sequencing text file, which is flanked by two constant strings. The substring, also termed smRNA or insert, is stored in a MySQL and BlastN database. These inserts are then compared using BlastN to locally installed databases allowing the rapid comparison of the insert to both the growing smRNA database and to other static sequence databases. Our laboratory used Ebbie to analyze scores of DNA sequencing data originating from an smRNA cloning project[6]. Through its built-in instant analysis of all inserts using BlastN, we were able to quickly identify 33 groups of smRNAs from ~700 database entries. This clustering allowed the easy identification of novel and highly expressed clusters of smRNAs. Ebbie is available under GNU GPL and currently implemented on CONCLUSION: Ebbie was designed for medium sized smRNA cloning projects with about 1,000 database entries [6-8].Ebbie can be used for any type of sequence analysis where two constant primer regions flank a sequence of interest. The reliable storage of inserts, and their annotation in a MySQL database, BlastN[9] comparison of new inserts to dynamic and static databases make it a powerful new tool in any laboratory using DNA sequencing. Ebbie also prevents manual mistakes during the excision process and speeds up annotation and data-entry. Once the server is installed locally, its access can be restricted to protect sensitive new DNA sequencing data. Ebbie was primarily designed for smRNA cloning projects, but can be applied to a variety of RNA and DNA cloning projects[2,3,10,11]
Quantum-state steering in optomechanical devices
We show that optomechanical systems in the quantum regime can be used to
demonstrate EPR-type quantum entanglement between the optical field and the
mechanical oscillator, via quantum-state steering. Namely, the conditional
quantum state of the mechanical oscillator can be steered into different
quantum states depending the choice made on which quadrature of the out-going
field is to be measured via homodyne detection. More specifically, if quantum
radiation pressure force dominates over thermal force, the oscillator's quantum
state is steerable with a photodetection efficiency as low as 50%, approaching
the ideal limit shown by Wiseman and Gambetta [Phys. Rev. Lett. 108,
220402 (2012)]. We also show that requirement for steerability is the same as
those for achieving sub-Heisenberg state tomography using the same experimental
setup
Quantum Enhancement of the Zero-Area Sagnac Interferometer Topology for Gravitational Wave Detection
Only a few years ago, it was realized that the zero-area Sagnac
interferometer topology is able to perform quantum nondemolition measurements
of position changes of a mechanical oscillator. Here, we experimentally show
that such an interferometer can also be efficiently enhanced by squeezed light.
We achieved a nonclassical sensitivity improvement of up to 8.2 dB, limited by
optical loss inside our interferometer. Measurements performed directly on our
squeezed-light laser output revealed squeezing of 12.7 dB. We show that the
sensitivity of a squeezed-light enhanced Sagnac interferometer can surpass the
standard quantum limit for a broad spectrum of signal frequencies without the
need for filter cavities as required for Michelson interferometers. The Sagnac
topology is therefore a powerful option for future gravitational-wave
detectors, such as the Einstein Telescope, whose design is currently being
studied.Comment: 4 pages, 4 figure
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