How to Build a Photonic Quantum Computer

[@axeowny8023]

The coin bending trick is caused be the rolling shutter effect. Because a camera takes parts of a picture at a time (untill it has completed the whole picture) instead of snapping the whole picture at ones; it distorts or bends objects that move faster than the speed of completing the whole picture.

[@DrBenMiles]

Awesome answer. :) Thanks! As I said above, I was going to make a video conglomerating all the responses, but that plan went out the window a bit! I just wanted to make sure I said thanks for the response. Really appreciate it!

[@BruceElliott]

The rolling shutter effect (i.e. the reason for appearance of a bent coin in this video) was recently cited in this video: kzbin.info/www/bejne/fHy7gKiZjadnl5o, which describes the reconstruction of audio signals from video of objects vibrating in response to sound waves, such a plant foliage or empty potato chip bags (see 3:07 in that video (ignore the link - KZbin inserts one to this video) for a depiction of the effect that closely resembles the bent coin). They used the rolling shutter effect to reconstruct audio signals that had a higher frequency than the frame rate of the video. The number of people on the planet who know what "rolling shutter effect" means has probably increased dramatically in the past ten days.

[@ocksee]

The rolling shutter effect is cited, but not explained. The reason why it happens is because of the way the scene picked up by the optical (cmos) chip in the camera is displayed using what is referred to as 'progressive' (the P in 480p or 720p). The pixels on the screen are not updated all at once like a flash of images. Rather, the image is updated row by row, starting with the first row of pixels and then to the second and onward. When the framerate of the recording device is too slow to capture the movement of the object, the result is that the object has actually changed position between the time when line A of pixels is updated and line B. For another common example of this effect, watch a video of an airplane propeller. You'll see the tips of the propeller blades bend backwards as if flexing in the wind, when really it's just because the framerate on the camera is too slow to catching the fast-moving blade all in one scan.

[@DrBenMiles]

Awesome answer. :) Thanks! I was going to make a video conglomerating all the responses, but that plan went out the window a bit! I just wanted to make sure I said thanks for the response. Really appreciate it!

[@ADickIHave]

This channel has so much potential! Would love to see where it is in 5 years time

[@WorldCreativity]

It'd now 😇

[@martinpetersson4350]

Good i just discovered this video looking for diy photonics projects lol

[@john-alanpascoe5848]

Really cool to see a quantum phenomenon become 'real' (I guess tangible is a better word) like this, thanks to you and Jacques for sharing!

[@DrBenMiles]

John-Alan Pascoe Glad you liked it :)

[@ferashamdan4252]

The music background impaired my listening ability to these smart people.

[@nabilfadili9414]

Great topic! Thanks!

[@OwenWithAHammer]

Loved the topic. Some parts were a bit hard to follow but still very interesting. Can't wait to see what the next video will hold.

[@DrBenMiles]

OwenWithAHammer Thank you Mr. Hammer :)

[@mattphillips538]

When you say "In both states at once", do you mean in sense of S1 AND S2, or did you mean S1 OR S2 (inclusive)?

[@HaydenHatTrick]

1:55 My thoughts exactly. You made me so happy to finally hear someone else say that :P

[@alexgee3750]

The coin appears curved due to something known as the rolling shutter effect - an effect due the cameras method capturing an image. en.wikipedia.org/wiki/File:Rolling_shutter_effect_animation.gif

[@naserrouhi5162]

That's really cool. It will change the world for sure.

[@buckrogers5331]

Hmm, this QC is built using a photons. There are others built using the quantum states of the electron from a phosphate crystal. But I love this channel for it shows the real setup. No amount of drawing can replace what is physically there to see and grasp.

[@BystroffG]

I noticed that about the spinning coin. Camera effects. How the data is captured or stored or projected is how we get those specific kinds of effects. It is also how we see lizard people or disappearing people on street corners from surveillance cameras. I'm just happy it wasn't my brain, when you mentioned it yourself.

[@timd3469]

30 seconds into the video, and I had to give a like. I love the thought of the multiverse! Even though in at least one of them, Bruce Wayne's dad is Batman, and I don't care for his Batman. But... that also means an infinite amount of cool Bruce Wayne Batmans. Now to rewind and watch the video.

[@julienvm]

Hey, your videos are awesome, I can't stop putting them on twitter! Keep up the good work! Just wanted to mention that I have the same rolling shutter effect (aka jello effect) when I film a view from a plane, and the prop ruins the shot. It's quite uncool, and it seems that all my cameras have a similar sensor because I get the effect on each (gopro, virb, sony rx100). So I now use a ND filter, and that greatly reduces the effect (but I'm not sure why!). I don't know if that can be of use to you, and what the result is on a spinning coin. The ND filter greatly reduces the light that comes in the sensor, so it's no good for filming inside. Thanks for your videos!!

[@DrBenMiles]

Using an ND filter fixes rolling shutter?! I hadn't ever thought of that. That's really interesting trick. What made you think to try it? If I had to guess, it probably forces you/the camera to change the exposure time to allow sufficient light onto the chip. I would guess rolling shutter occurs most noticeably at fast exposure time, as the camera tries to take what it thinks is a snapshot of the world, and what allows you to see the prop frozen in time (although warped). Lengthening the exposure time lets more light in and integrates over the prop position so you either see it as a circular blur or not at all. Thanks julienvm . Interesting stuff! Really appreciate it.

[@julienvm]

whentheappledrops You're spot on! Now that I think of it, that's exactly what happens: the ND filter simply increases the exposure time! The way I stumbled upon this trick is simply that when purchasing the Garmin Virb camera, a "prop filter" was offered as an optional accessory. This a camera that has interesting features for pilots (like gps tracking and overlay) so they offered other pilot accessories like this one. But there's a ton of videos on youtube as well. Where do you work/study? I'm currently trying to connect with physicists because after my engineering degree, and business experience, I'm wondering if I should consider joining physics work in a way or another, maybe with a PhD or just with my current background... Your videos are really good! Thanks for that!

[@DrBenMiles]

julienvm ah, nice! Good stuff. Not something I'd thought about looking into. I'm at the Bristol Center for Nano Science and Quantum Information (NSQI) part of the University of Bristol, UK. PhD's are fun. Maybe not for everyone, but if you find yourself in the right place at the right time they are a great experience. If you want to be waist deep in science- a PhD is perfect, but there are tons of support roles at industry labs that emphasize a better understanding of engineering. One thing I will say is that PhD's can be pretty hectic...hence the slow roll out of videos over the past month(s). I'll get back on it soon. Thanks for the support!

[@syawkcab]

I am so confused and lost. Here are some questions I have: 1. In the Hong Ou Mandel effect, why can't you see one photon coming out of each path? Why/how do they deconstructively interfere? 2. Where did the 50,000 possible outcomes of five photons come from? How was this number calculated? Is this number including or excluding outcomes you don't see because they deconstructively interfere? 3. What exactly is the calculation they are trying to compute? The number of possible outcomes in Hong Ou Mandel setup with an X amount of paths and a Y amount of photons? 4. What do the axes on the graphs at 7:51 represent? Which point is the origin? 5. Can someone clarify what he means when he says there are 200 events? What is considered an event? whentheappledrops

[@DrBenMiles]

syawkcab Oh shoot, I didn't see your comment, sorry about that! 1.) The probabilities destructively interfere as the probability of them occurring is equal and opposite so they are suppressed (quantum mechanics). There isn't a nice direct classical analog. 2) 50,000 outcomes are from 5 photons interacting over 21 modes (fibers). The number is calculated by "brute force" on a computer an extension of the 2 photon Hong Ou Mandel example in the video. 3) What they are trying to do is see if experimentally reproducing the set up, and collecting a small about of data from it (200 trials- which means 200 photon events collected from it) can simulate enough of the distribution for them to solve it without the need to crunch the numbers. 4) The graph shows that the photon events cluster or produce "boson clouds" similar to the Hong Ou Mandel effect. Hope that helped :)

[@fliu5282]

oh boy you have no idea...Google is building a Quantum Computer that uses Light-based Memory Chip to store data permanently and the storage capacity is - an infinity. There will be no more chip or tape storage. All computation will be done in light and data is stored in photon. The effect? Your regular desktop has a computation power of a "supercomputer".

[@Trump_y_Gore_Won]

Nice video, thanks Dr. Miles - can you revisit this topic, in light (no pun :-)) of recent developments? Thanks!

[@ToxicBassUK]

Very interesting :)

[@ranier33]

You say that the applications for this quantum computer are very niche, what would be some examples of these?

[@nihilist809]

The coin looks like that because of your camera and it's sensor: Propeller Distortion Explained: CCD vs CMOS Cameras www.reddit.com/r/woahdude/comments/26z598/cameras_rolling_shutter_effect_explained/

[@DrBenMiles]

Thanks for the response! As I said above, I was going to make a video conglomerating all the responses, but that plan went out the window a bit! I just wanted to make sure I said thanks for the response. Really appreciate it!

[@CERN1954]

Its just a rolling shutter effect.

[@beofonemind]

awesome! i don't understand half of it just yet.

[@tsetse]

I like the tree logo

[@Cyc0de]

i wanted to know more about how calculations or even just simple circuits are done and.. learned nothing. just like in most other videos "explaining how a photonic quantum computer works". I learned more about the laser used than actual the part that does the computation in this video. This is so annoying.

[@aariioo]

The music makes me want to snap my own neck, but otherwise, good video.

[@glypton]

it's not a computation, it's a quantum experiment !

[@ThompPL1]

Trying to explain this to elementary school students is causing problems for the rest of us college educated folks.

[@xythiera7255]

2021 and its reality

[@gina888warhol1]

You sound like the Beetles!