Generation of polarization entangled photons

[AlexHT]

Hi,

What crystal do I need to generate polarization entangled photons? I read BBO (beta-BaB2O4) crystal are needed but when I call the engineers at commercial companies and mention the term "entangled photons" it goes way over their heads and they just say they don't make this crystal.

I am trying to use a laser diode at 856nm (give or take) and send it trough a second harmonic generator (now at 428nm) to hit the BBO crystal with. Much like it is described in the paper : http://xqp.physik.uni-muenchen.de/publ/apl_79_869_2001.pdf

Anyone has any suggestions - for a good company or share their experience with this field?

Thanks in advance!

 

[DrChinese]

Try this:

Downconversion Crystal: Cleveland Crystals, http://www.clevelandcrystals.com. Beta-barium borate ~BBO!
crystal, 3 mm long, for converting a cw 405-nm input to an
810-nm output, 3° cone angle on signal and idler, XH0503
housing with a 5-mm aperture, Humidity-barrier antireflective
coatings on the crystal faces, nitrogen purge connections,
and no windows; $2,160.

 

[denian]

I have experience with generating polarization entangled photons and can provide some guidance on your question. BBO (beta-BaB2O4) crystals are indeed commonly used for this purpose, as they have a high nonlinear coefficient and can efficiently convert the wavelength of a laser beam to its second harmonic. However, it is important to note that not all BBO crystals are suitable for generating polarization entangled photons. The crystal must have a high optical quality and be cut at the correct angle to ensure the desired entanglement.

In terms of finding a reliable source for these crystals, I recommend reaching out to academic research groups or specialized companies that focus on photonics or quantum optics. They may be able to provide you with the specific type of BBO crystal you need for your experiment. It is also important to clearly communicate your requirements and goals when contacting these companies, as not all of them may have experience with entangled photons.

Additionally, you may want to consider alternative methods for generating polarization entangled photons, such as using spontaneous parametric down-conversion (SPDC) in a nonlinear crystal. This method has been widely used in research labs and may be a more accessible option for your experiment.

I hope this helps and wish you the best of luck in your research.