2,872 research outputs found
Isocurvature Perturbations of Dark Energy and Dark Matter from the Swampland Conjecture
We point out that the recently proposed Swampland conjecture on the potential
gradient can lead to isocurvature perturbations of dark energy, if the
quintessence field acquires large quantum fluctuations during high-scale
inflation preferred by the conjecture. Also, if the quintessence field is
coupled to a dark sector that contains dark matter, isocurvature perturbation
of dark matter is similarly induced. Both isocurvature perturbations can be
suppressed if the quintessence potential allows a tracker solution in the early
Universe. We find that a vector field of mass meV is an
excellent dark matter candidate in this context, not only because the right
abundance is known to be produced by quantum fluctuations during high-scale
inflation without running afoul of isocurvature bounds, but also because its
coupling to the quintessence does not spoil the flatness of the potential.Comment: 14 pages, 1 figure; (v2) minor changes, Fig. 1 adde
Temporally multiplexed superposition states of continuous variables
We study non-Gaussian states generated by two-photon subtraction from a cw
squeezed light source. In a cw scheme one can subtract two photons from the
source with a designated time separation and can genarate temporally
multiplexed superposition states of continuous variables. We numerically study
the properties of these states in the light of bosonic interference in the time
domain. In an appropriate temporal mode amplified kittens are produced in a
region where the time separation is comparable with the correlation time of
squeezed packets.Comment: 12 pages, 10 figure
Large amplitude coherent state superposition generated by a time-separated two-photon subtraction from a continuous wave squeezed vacuum
Theoretical analysis is given for a two-photon subtraction from a continuous
wave (CW) squeezed vacuum with finite time separation between two detection
events. In the CW photon subtraction process, the generated states are
inevitably described by temporal mutimode states. Our approach is based on
Schr\"{o}dinger picture which provides mathematically simple forms and an
intuitive understanding of its multimode structure. We show that, in our
process, the photon subtracted squeezed vacuum is generated in two temporal
modes and one of these modes acts as an ancillary mode to make the other one a
large amplitude coherent state superposition.Comment: 9 pages, 8 figure
心臓内血流動態可視化のための血球エコーの高フレームレート超音波イメージング
Tohoku University金井浩課
- …