3,403 research outputs found
Cryogenic Q-factor measurement of optical substrates for optimization of gravitational wave detectors
Future generations of gravitational wave interferometers are likely to be operated at cryogenic temperatures because one of the sensitivity limiting factors of the present generation is the thermal noise of end mirrors and beam splitters that occurs in the optical substrates as well as in the dielectric coatings. A possible method for minimizing thermal noise is cooling to cryogenic temperatures, maximizing the mechanical quality factor Q, and maximizing the eigenfrequencies of the substrate. We present experimental details of a new cryogenic apparatus that is suitable for the measurement of the temperature-dependent Q-factor of reflective, transmissive as well as nano-structured grating optics down to 5 K. In particular, the SQUID-based and the optical interferometric approaches to the measurement of the amplitude of vibrating test bodies are compared and the method of ring-down recording is described
Experimental demonstration of continuous variable purification of squeezed states
We report on the first experimental demonstration of purification of
nonclassical continuous variable states. The protocol uses two copies of
phase-diffused states overlapped on a beam splitter and provides Gaussified,
less mixed states with the degree of squeezing improved. The protocol uses only
linear optical devices such as beam splitters and homodyne detection, thereby
proving these optical elements can be used for successful purification of this
type of state decoherence which occurs in optical transmission channels
Demonstration of 3-port grating phase relations
We experimentally demonstrate the phase relations of 3-port gratings by
investigating 3-port coupled Fabry-Perot cavities. Two different gratings which
have the same 1st order diffraction efficiency but differ substantially in
their 2nd order diffraction efficiency have been designed and manufactured.
Using the gratings as couplers to Fabry-Perot cavities we could validate the
results of an earlier theoretical description of the phases at a three port
grating
Input-output relations for a 3-port grating coupled Fabry-Perot cavity
We analyze an optical 3-port reflection grating by means of a scattering
matrix formalism. Amplitude and phase relations between the 3 ports, i.e. the 3
orders of diffraction are derived. Such a grating can be used as an
all-reflective, low-loss coupler to Fabry-Perot cavities. We derive the input
output relations of a 3-port grating coupled cavity and find distinct
properties not present in 2-port coupled cavities. The cavity relations further
reveal that the 3-port coupler can be designed such that the additional cavity
port interferes destructively. In this case the all-reflective, low-loss,
single-ended Fabry-Perot cavity becomes equivalent to a standard transmissive,
2-port coupled cavity
Three-port beam splitters-combiners for interferometer applications
We derive generic phase and amplitude coupling relations for beam
splitters-combiners that couple a single port with three output ports or input
ports, respectively. We apply the coupling relations to a reflection grating
that serves as a coupler to a single-ended Fabry-Perot ring cavity. In the
impedance-matched case such an interferometer can act as an all-reflective ring
mode cleaner. It is further shown that in the highly undercoupled case almost
complete separation of carrier power and phase signal from a cavity strain can
be achieved
Preparing the bound instance of quantum entanglement
Among the possibly most intriguing aspects of quantum entanglement is that it
comes in "free" and "bound" instances. Bound entangled states require entangled
states in preparation but, once realized, no free entanglement and therefore no
pure maximally entangled pairs can be regained. Their existence hence certifies
an intrinsic irreversibility of entanglement in nature and suggests a
connection with thermodynamics. In this work, we present a first experimental
unconditional preparation and detection of a bound entangled state of light. We
consider continuous-variable entanglement, use convex optimization to identify
regimes rendering its bound character well certifiable, and realize an
experiment that continuously produced a distributed bound entangled state with
an extraordinary and unprecedented significance of more than ten standard
deviations away from both separability and distillability. Our results show
that the approach chosen allows for the efficient and precise preparation of
multimode entangled states of light with various applications in quantum
information, quantum state engineering and high precision metrology.Comment: The final version accounts for a recent comment in Nature Physics
[24] clarifying that a previous claim of having generated bound entanglement
[23] was not supported by the authors' data. We also extended our
introduction and discussion and also added reference
PHYLOGENY OF THE ARCHAEBACTERIA AND EUKARYOTES: HOMOLOGY OF THE DNA-DEPENDENT RNA POLYMERASES
Recovery of continuous wave squeezing at low frequencies
We propose and demonstrate a system that produces squeezed vacuum using a
pair of optical parametric amplifiers. This scheme allows the production of
phase sidebands on the squeezed vacuum which facilitate phase locking in
downstream applications. We observe strong, stably locked, continuous wave
vacuum squeezing at frequencies as low as 220 kHz. We propose an alternative
resonator configuration to overcome low frequency squeezing degradation caused
by the optical parametric amplifiers.Comment: 9 pages, 4 figure
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Explaining how to play real-time strategy games
Real-time strategy games share many aspects with real situations in domains such as battle planning, air traffic control, and emergency response team management which makes them appealing test-beds for Artificial Intelligence (AI) and machine learning. End-user annotations could help to provide supplemental information for learning algorithms, especially when training data is sparse. This paper presents a formative study to uncover how experienced users explain game play in real-time strategy games. We report the results of our analysis of explanations and discuss their characteristics that could support the design of systems for use by experienced real-time strategy game users in specifying or annotating strategy-oriented behavior
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