278 research outputs found
Measurement by FIB on the ISS: Two Emissions of Solar Neutrons Detected?
A new type of solar neutron detector (FIB) was launched onboard the Space
Shuttle Endeavour on July 16, 2009, and it began collecting data at the
International Space Station (ISS) on August 25, 2009. This paper summarizes the
three years of observations obtained by the solar neutron detector FIB until
the end of July 2012. The solar neutron detector FIB can determine both the
energy and arrival direction of neutrons. We measured the energy spectra of
background neutrons over the SAA region and elsewhere, and found the typical
trigger rates to be 20 counts/sec and 0.22 counts/sec, respectively. It is
possible to identify solar neutrons to within a level of 0.028 counts/sec,
provided that directional information is applied. Solar neutrons were observed
in association with the M-class solar flares that occurred on March 7 (M3.7)
and June 7 (M2.5) of 2011. This marked the first time that neutrons were
observed in M-class solar flares. A possible interpretaion of the prodcution
process is provided.Comment: 36 pages, 16 figures, and 3 Tables; Advanced in Astronmy, 2012,
Special issue on Cosmic Ray Variablity:Century of Its Obseravtion
Two-stage spinel growth in the high-grade metapelites of the central Kerala Khondalite Belt : Implication for prograde
Time-optimal CNOT between indirectly coupled qubits in a linear Ising chain
We give analytical solutions for the time-optimal synthesis of entangling
gates between indirectly coupled qubits 1 and 3 in a linear spin chain of three
qubits subject to an Ising Hamiltonian interaction with equal coupling plus
a local magnetic field acting on the intermediate qubit. The energy available
is fixed, but we relax the standard assumption of instantaneous unitary
operations acting on single qubits. The time required for performing an
entangling gate which is equivalent, modulo local unitary operations, to the
between the indirectly coupled qubits 1 and 3 is
, i.e. faster than a previous estimate based on a similar
Hamiltonian and the assumption of local unitaries with zero time cost.
Furthermore, performing a simple Walsh-Hadamard rotation in the Hlibert space
of qubit 3 shows that the time-optimal synthesis of the (which acts as the identity when the control qubit 1 is in the state
, while if the control qubit is in the state the target
qubit 3 is flipped as ) also requires the same
time .Comment: 9 pages; minor modification
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