376 research outputs found
Earthquake Forecast via Neutrino Tomography
We discuss the possibility of forecasting earthquakes by means of
(anti)neutrino tomography. Antineutrinos emitted from reactors are used as a
probe. As the antineutrinos traverse through a region prone to earthquakes,
observable variations in the matter effect on the antineutrino oscillation
would provide a tomography of the vicinity of the region. In this preliminary
work, we adopt a simplified model for the geometrical profile and matter
density in a fault zone. We calculate the survival probability of electron
antineutrinos for cases without and with an anomalous accumulation of electrons
which can be considered as a clear signal of the coming earthquake, at the
geological region with a fault zone, and find that the variation may reach as
much as 3% for emitted from a reactor. The case for a beam
from a neutrino factory is also investigated, and it is noted that, because of
the typically high energy associated with such neutrinos, the oscillation
length is too large and the resultant variation is not practically observable.
Our conclusion is that with the present reactor facilities and detection
techniques, it is still a difficult task to make an earthquake forecast using
such a scheme, though it seems to be possible from a theoretical point of view
while ignoring some uncertainties. However, with the development of the
geology, especially the knowledge about the fault zone, and with the
improvement of the detection techniques, etc., there is hope that a medium-term
earthquake forecast would be feasible.Comment: 6 pages, 4 figures, 1 tabl
Entanglement-interference complementarity and experimental demonstration in a superconducting circuit
Abstract Quantum entanglement between an interfering particle and a detector for acquiring the which-path information plays a central role for enforcing Bohr’s complementarity principle. However, the quantitative relation between this entanglement and the fringe visibility remains untouched upon for an initial mixed state. Here we find an equality for quantifying this relation. Our equality characterizes how well the interference pattern can be preserved when an interfering particle, initially carrying a definite amount of coherence, is entangled, to a certain degree, with a which-path detector. This equality provides a connection between entanglement and interference in the unified framework of coherence, revealing the quantitative entanglement-interference complementarity. We experimentally demonstrate this relation with a superconducting circuit, where a resonator serves as a which-path detector for an interfering qubit. The measured fringe visibility of the qubit’s Ramsey signal and the qubit-resonator entanglement exhibit a complementary relation, in well agreement with the theoretical prediction
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