tag:blogger.com,1999:blog-6977755959349847093.post3241816794003916277..comments2024-03-01T21:53:15.921-08:00Comments on The Pith of Performance: New Quantum CameraNeil Guntherhttp://www.blogger.com/profile/11441377418482735926noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-6977755959349847093.post-89278148122834166002009-01-26T10:08:00.000-08:002009-01-26T10:08:00.000-08:00Because the relatively low production rate was a k...Because the relatively low production rate was a killer for some of our<BR/>experiments, I know we discussed this topic. My recollection is that it's<BR/>not so easy to increase the rate of super-Poisson photons. Without<BR/>getting into all the details, it's a Goldilocks problem. You don't want a<BR/>source that is completely coherent (like a laser) and you don't want a<BR/>source that is completely incoherent (like a light bulb). You want something <BR/>in between that's just right (like a Hg lamp), without reducing your overall intensity.<BR/><BR/>But never say never. A similar issue concerned the production rate of<BR/>entangled bi-photons. The first detection ca. 1948 involved the decay of<BR/>positronium. This, and later methods, have since been replaced by<BR/>spontaneous parametric down conversion using birefringent crystals, <BR/>http://en.wikipedia.org/wiki/Spontaneous_parametric_down_conversion .<BR/>Quantum dots might turn out to be useful, http://physics.technion.ac.il/~dg/PAPERS/PRL/prl01.pdf, although they're more usually associated with sub-Poisson sourcing.Neil Guntherhttps://www.blogger.com/profile/11441377418482735926noreply@blogger.comtag:blogger.com,1999:blog-6977755959349847093.post-46024627535483592812009-01-26T09:28:00.000-08:002009-01-26T09:28:00.000-08:00See Table 1 in our paper. The implication is that ...See Table 1 in our paper. The implication is that you need 2 cameras; the<BR/>regular kind and ours. Currently, researchers are just using a regular<BR/>camera. In the context of BEC detection, you must have homogeneous matter<BR/>(e.g., atoms, polaritons) in order to facilitate potential condensate<BR/>production. The question becomes: What state is that homogeneous matter in? <BR/><BR/>In principle, a non-condensate blob (call it "!BEC") could act as either a<BR/>fully incoherent or a *semi-coherent* light source. A fully incoherent blob<BR/>would wash everything out, so no interference "image" would appear in<BR/>either camera. That would include your !BEC and not sticky. (Col 2 of Table<BR/>1) On the other hand, a semi-coherent !BEC blob will produce an<BR/>interference "image" in *both* cameras. (Col 4 of Table 1)<BR/><BR/>If, however, you attain the right conditions and some of the semi-coherent<BR/>blob now transitions to a genuine condensate, those areas of BEC within the<BR/>!BEC blob will act as fully *coherent* sources (by definition), at which<BR/>point that part of the "image" will disappear in our camera but remain in<BR/>the regular camera. (Col 3 of Table 1)Neil Guntherhttps://www.blogger.com/profile/11441377418482735926noreply@blogger.comtag:blogger.com,1999:blog-6977755959349847093.post-44741412311438671062009-01-25T16:13:00.000-08:002009-01-25T16:13:00.000-08:00Nice post. Here is a tangential question. Is it po...Nice post. Here is a tangential question. Is it possible to create a light source that will efficiently produce many of these photon pairs.Vincenthttps://www.blogger.com/profile/06197767693437233086noreply@blogger.com