322 research outputs found
Classical reconstruction of interference patterns of position-wavevector-entangled photon pairs by time-reversal method
The quantum interference of entangled photons forms a key phenomenon
underlying various quantum-optical technologies. It is known that the quantum
interference patterns of entangled photon pairs can be reconstructed
classically by the time-reversal method; however, the time-reversal method has
been applied only to time-frequency-entangled two-photon systems in previous
experiments. Here, for the first time, we apply the time-reversal method to the
position-wavevector-entangled two-photon systems: the two-photon Young
interferometer and the two-photon beam focusing system. We experimentally
demonstrate that the time-reversed systems classically reconstruct the same
interference patterns as the position-wavevector-entangled two-photon systems.Comment: 10 pages, 8 figure
Observation of nonlinear variations in three-vertex geometric phase in two-photon polarization qutrit
We experimentally observed nonlinear variations in the three-vertex geometric
phase in a two- photon polarization qutrit. The three-vertex geometric phase is
defined by three quantum states, which generally forms a three-state (qutrit)
system. By changing one of the three constituent states, we observed two rapid
increases in the three-vertex geometric phase. The observed variations are
inherent in a three-state system and cannot be observed in a two-state system.
We used a time-reversed two-photon interferometer to measure the geometric
phase with much more intense signals than those of a typical two-photon
interferometer.Comment: 6 pages, 5 figure
Time-reversed two-photon interferometry for phase super-resolution
We observed two-photon phase super-resolution in an unbalanced Michelson
interferometer with classical Gaussian laser pulses. Our work is a
time-reversed version of a two-photon interference experiment using an
unbalanced Michelson interferometer. A measured interferogram exhibits
two-photon phase super-resolution with a high visibility of 97.9% \pm 0.4%. Its
coherence length is about 22 times longer than that of the input laser pulses.
It is a classical analogue to the large difference between the one- and
two-photon coherence lengths of entangled photon pairs.Comment: 6 pages, 4 figure
Cooperation of the IFT-A complex with the IFT-B complex is required for ciliary retrograde protein trafficking and GPCR import
Cilia sense and transduce extracellular signals via specific receptors. The intraflagellar transport (IFT) machinery mediates not only bidirectional protein trafficking within cilia but also the import/export of ciliary proteins across the ciliary gate. The IFT machinery is known to comprise two multisubunit complexes, namely, IFT-A and IFT-B; however, little is known about how the two complexes cooperate to mediate ciliary protein trafficking. We here show that IFT144-IFT122 from IFT-A and IFT88-IFT52 from IFT-B make major contributions to the interface between the two complexes. Exogenous expression of the IFT88(Δα) mutant, which has decreased binding to IFT-A, partially restores the ciliogenesis defect of IFT88-knockout (KO) cells. However, IFT88(Δα)-expressing IFT88-KO cells demonstrate a defect in IFT-A entry into cilia, aberrant accumulation of IFT-B proteins at the bulged ciliary tips, and impaired import of ciliary GPCRs. Furthermore, overaccumulated IFT proteins at the bulged tips appeared to be released as extracellular vesicles. These phenotypes of IFT88(Δα)-expressing IFT88-KO cells resembled those of IFT144-KO cells. These observations together indicate that the IFT-A complex cooperates with the IFT-B complex to mediate the ciliary entry of GPCRs as well as retrograde trafficking of the IFT machinery from the ciliary tip. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text]
Direct measurement of ultrafast temporal wavefunctions
The large capacity and robustness of information encoding in the temporal
mode of photons is important in quantum information processing, in which
characterizing temporal quantum states with high usability and time resolution
is essential. We propose and demonstrate a direct measurement method of
temporal complex wavefunctions for weak light at a single-photon level with
subpicosecond time resolution. Our direct measurement is realized by ultrafast
metrology of the interference between the light under test and self-generated
monochromatic reference light; no external reference light or complicated
post-processing algorithms are required. Hence, this method is versatile and
potentially widely applicable for temporal state characterization.Comment: 10 pages, 7 figure
Magnetic field effect on Fe-induced short-range magnetic correlation and electrical conductivity in BiPbSrCuFeO
We report electrical resistivity measurements and neutron diffraction studies
under magnetic fields of
BiPbSrCuFeO, in which hole
carriers are overdoped. This compound shows short-range incommensurate magnetic
correlation with incommensurability , whereas a Fe-free compound
shows no magnetic correlation. Resistivity shows an up turn at low temperature
in the form of and shows no superconductivity. We observe reduction
of resistivity by applying magnetic fields (i.e., a negative magnetoresistive
effect) at temperatures below the onset of short-range magnetic correlation.
Application of magnetic fields also suppresses the Fe induced incommensurate
magnetic correlation. We compare and contrast these observations with two
different models: 1) stripe order, and 2) dilute magnetic moments in a metallic
alloy, with associated Kondo behavior. The latter picture appears to be more
relevant to the present results.Comment: 7 pages, 5 figure
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