a-photonic-system-for-generating-unconditional-polarization-entangled

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

We present a high-performance source of unconditional polarization-entangled photons that have a high-emission rate, a broadband distribution, are ...

Polarized light imaging (PLI) enables detecting the orientation of myelinated axon bundles in brain slices at microscopic resolution without histological staining. However, standard PLI requires labor-intensive procedures such as mounting brain cryosections on slide glasses. We developed an optical system that does not require a mounting procedure for PLI. Specifically, we developed an optical system to perform PLI in reflection mode (rPLI) instead of employing transmitted light as in standard PLI. We integrated this rPLI system with a conventional vibratome slicer whose cutting blade surface is a mirror. This combination allowed PLI measurements directly during the slicing procedure at room temperature. Thus, mounting procedure for PLI is not necessary. As a proof-of-concept experiment, a perfusion-fixed brain of a mouse was embedded in gelatin-containing agar and cut serially at 40~200 μm intervals. The slicing procedure was temporarily halted after each cut to capture the PLI images of the slice on the reflecting blade surface while the slice was still held up by the agar block. The orientation of the fiber bundle estimated with this method agreed with the results obtained from previous reports. Combination of a popular vibratome slicer and our rPLI system that uses versatile and inexpensive optical components would increase popularity of PLI and facilitates connectome studies at microscopic resolution. RESEARCH HIGHLIGHTS: Polarized light imaging (PLI) of brain slices was realized by using reflected light (rPLI) instead of transmitted light. The rPLI method allows detecting the myelinated fiber bundle orientation during slice preparation.

Visualization of myelinated fiber bundles orientation during brain slice preparation by reflection polarized light microscopy.

Quantum interference, like Hong-Ou-Mandel interference, has played an important role to test fundamental concepts in quantum physics. We experimentally show that the multiple quantum interference effects enable the generation of high-performance polarization entangled photons. These photons have a high-emission rate, are degenerate, have a broadband distribution, and are postselection free. A quantum interferometric scheme, based on a round-trip configuration of a double-pass polarization Sagnac interferometer, makes it possible to use the large generation efficiency of polarization entangled photons in the process of parametric down-conversion and to separate degenerate photon pairs into different optical modes with no requirement of postselection. We demonstrate experimentally that multiple quantum interference is not only an interesting fundamental quantum optical phenomenon but can be used for novel photonic quantum information technologies.

Article	Year
Visualization of myelinated fiber bundles orientation during brain slice preparation by reflection polarized light microscopy. Microscopy research and technique\| PubMed ID: 30351467	2018
Quantum interferometric generation of polarization entangled photons. Scientific reports\| PubMed ID: 30356066	2018

Kaoru Sanaka

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