| 0:00:06 | in nineteen fifty six hand bring brands standard the scientific community when he reported the |
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| 0:00:12 | photons emitted by serious the brightest or in the night sky had a tendency to |
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| 0:00:17 | write together in client on these detectors |
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| 0:00:20 | that is to say unlike cars on the highway or people passing by or any |
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| 0:00:25 | other randomly distributed classical objects whose time of arrival would be recorded like this |
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| 0:00:31 | and bring brian and is mathematician calling twist find out the photons from a thermal |
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| 0:00:37 | source are detected like this actually more like london buses |
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| 0:00:42 | there is a way to have photons arrive like cars or people one can use |
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| 0:00:47 | a laser instead of a chaotic source |
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| 0:00:50 | the first type information comes from single photon images like a quantum dot the produce |
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| 0:00:56 | false ones which avoid each other |
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| 0:00:58 | the lower proposed a consequence g two defined as shown here to describe these situations |
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| 0:01:05 | g two is equal to one for uncorrelated events |
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| 0:01:09 | it is greater than one for circle bunching events where photons are clustered it is |
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| 0:01:14 | more than one ideally zero for so called anti bunching events when photons avoid each |
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| 0:01:20 | other |
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| 0:01:21 | for instance one can compute g two from the lighting dated by a quantum dots |
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| 0:01:26 | in the micro cavity just the following spectral lines right one would find a value |
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| 0:01:30 | close to zero as the emission is anti bunch this is when detecting we'll phones |
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| 0:01:35 | on from the system |
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| 0:01:36 | but what if we select only those in this frequency window is that each to |
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| 0:01:40 | the same as when detecting at all frequencies one can also correlate photons from two |
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| 0:01:45 | frequency windows experimentally this is an easy thing to accomplish one million supposes the filter |
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| 0:01:51 | before catching forms ones |
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| 0:01:54 | theoretically however such questions are extremely difficult to resolve despite the best efforts of yours |
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| 0:02:00 | since the links nineteen seventies only the force of heavy algebra and various approximations will |
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| 0:02:06 | be you results and then only for particular cases of simple systems |
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| 0:02:11 | in physical review letters we have recently presented a way around this obstacle and show |
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| 0:02:16 | how to readily computed g n of frequency filtered photons with no restriction whatsoever on |
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| 0:02:22 | the number of phones or on the type of system |
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| 0:02:25 | in the new journal of physics we apply this formalism to a wide class of |
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| 0:02:29 | fundamental quantum images for the case of two phones what coincidences |
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| 0:02:33 | in this short movie we will show some of the results for the case already |
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| 0:02:37 | discussed of a two level image or in the cavity |
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| 0:02:42 | this is the spectral shape again and we're going to present correlations of photons at |
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| 0:02:46 | all frequencies |
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| 0:02:48 | this is the results we call this a two photons spectrum |
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| 0:02:52 | in blue of the anti bunching correlations in white photons are uncorrelated in read their |
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| 0:02:59 | batch |
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| 0:03:00 | that is nigh bring our system into strong coupling by making the cavity of better |
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| 0:03:04 | quality this results in a so-called robbie tablet we see that in the two photons |
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| 0:03:09 | spectrum new patterns of here when the photon lifetime is very long an incredibly rich |
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| 0:03:15 | landscape of correlations emerges |
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| 0:03:18 | to give a qualitative idea of the most important features that just bring in the |
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| 0:03:22 | level structure of the system the so-called jane's cummings latter horizontal and vertical patterns are |
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| 0:03:28 | accounted for by successive emissions between this study |
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| 0:03:32 | this cascade is bunched this sequence on the other hand or this one or anti |
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| 0:03:38 | but as the system has to change its internal state to shift levels in this |
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| 0:03:43 | way |
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| 0:03:43 | more perplexing are these features and also these |
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| 0:03:47 | let us consider the anti diagonals that correspond to direct two photon emission this relaxes |
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| 0:03:53 | energy conservation since only the sum of the energies is fixed as the intermediate level |
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| 0:03:58 | is skipped over we call this type of two photon emission a leap from prior |
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| 0:04:03 | to photon emission is difficult to observe in general |
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| 0:04:07 | we shall have to reveal it and make it obvious |
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| 0:04:10 | there are countless configurations to revisit with this novel technique for instance this shows how |
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| 0:04:17 | the correlations remap when the quantum dot is teaching from the cavity |
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| 0:04:22 | and this shows what happens when increasing the pumping right |
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| 0:04:27 | we illustrate our last example with an important remark while a perfect detector resolution can |
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| 0:04:33 | be assumed for single photon spectra the filters line width is an integral part of |
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| 0:04:39 | frequency result photon counting to narrow filters give true results |
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| 0:04:44 | well blue ones are the features as shown here |
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| 0:04:47 | and of course in the limit a very broad filters the conventional results of hand |
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| 0:04:52 | brown and twist is recovered the study of we'll the other frequency ranges is josh |
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| 0:04:58 | at its beginning |
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