17 research outputs found
Record Photon Information Efficiency with Optical Clock Transmission and Recovery of 12.5 bits/photon over an Optical Channel with 77 dB Loss
We experimentally demonstrate optical detection at 12.5~bits per incident
photon, 9.4~dB higher than the theoretical limit of conventional coherent
detection. A single laser transmits both data and optical clock, undergoes
77~dB of attenuation before quantum detection followed by optical clock and
data recovery
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
First transmission of a 12D format across three coupled spatial modes of a 3-core coupled-core fiber at 4 bits/s/Hz
We demonstrate the first transmission of a space-division multiplexed 12D modulation format over a three-core coupled-core multicore fiber. The format occupies a single time slot spread across all three linearly-coupled spatial modes and shows improvements in MI and GMI after transmission compared to PDM-QPSK
The Search for Muon Neutrinos from Northern Hemisphere Gamma-Ray Bursts with AMANDA.
We present the results of the analysis of neutrino observations by the
Antarctic Muon and Neutrino Detector Array (AMANDA) correlated with photon
observations of more than 400 gamma-ray bursts (GRBs) in the Northern
Hemisphere from 1997 to 2003. During this time period, AMANDA's effective
collection area for muon neutrinos was larger than that of any other existing
detector. Based on our observations of zero neutrinos during and immediately
prior to the GRBs in the dataset, we set the most stringent upper limit on muon
neutrino emission correlated with gamma-ray bursts. Assuming a Waxman-Bahcall
spectrum and incorporating all systematic uncertainties, our flux upper limit
has a normalization at 1 PeV of
E^2{\Phi}_{\nu} {\leq} 6.0 \times 10^{-9} GeV cm^{-2} s^{-1} sr^{-1}, with
90% of the events expected within the energy range of ~10 TeV to ~3 PeV. The
impact of this limit on several theoretical models of GRBs is discussed, as
well as the future potential for detection of GRBs by next generation neutrino
telescopes. Finally, we briefly describe several modifications to this analysis
in order to apply it to other types of transient point sources.Comment: 44 pages, 10 figures; submitted to Astrophysical Journa
IceCube sensitivity for low-energy neutrinos from nearby supernovae
This paper describes the response of the IceCube neutrino telescope located
at the geographic South Pole to outbursts of MeV neutrinos from the core
collapse of nearby massive stars. IceCube was completed in December 2010
forming a lattice of 5160 photomultiplier tubes that monitor a volume of ~ 1
cubic kilometer in the deep Antarctic ice for particle induced photons. The
telescope was designed to detect neutrinos with energies greater than 100 GeV.
Owing to subfreezing ice temperatures, the photomultiplier dark noise rates are
particularly low. Hence IceCube can also detect large numbers of MeV neutrinos
by observing a collective rise in all photomultiplier rates on top of the dark
noise. With 2 ms timing resolution, IceCube can detect subtle features in the
temporal development of the supernova neutrino burst. For a supernova at the
galactic center, its sensitivity matches that of a background-free
megaton-scale supernova search experiment. The sensitivity decreases to 20
standard deviations at the galactic edge (30 kpc) and 6 standard deviations at
the Large Magellanic Cloud (50 kpc). IceCube is sending triggers from potential
supernovae to the Supernova Early Warning System. The sensitivity to neutrino
properties such as the neutrino hierarchy is discussed, as well as the
possibility to detect the neutronization burst, a short outbreak of electron
neutrinos released by electron capture on protons soon after collapse.
Tantalizing signatures, such as the formation of a quark star or a black hole
as well as the characteristics of shock waves, are investigated to illustrate
IceCube's capability for supernova detection.Comment: 17 pages, 16 figure