Simple Mod Turns Diodes Into Photon Counters

KentuckyFC writes "The standard way to detect single photons is to use an avalanche photodiode in which a single photon can trigger an avalanche of current. These devices have an important drawback, however. They cannot distinguish the arrival of a single photon from the simultaneous arrival of two or more. But a team of physicists in the UK has found a simple mod that turns avalanche photodiodes into photon counters. They say that in the first instants after the avalanche forms, its current is proportional to the number of photons that have struck. All you have to do is measure it at this early stage. That's like turning a Fiat 500 into a Ferrari. Photon counting is one of the enabling technologies behind optical quantum computing. A number of schemes are known in which it is necessary to count the arrival of 0, 1 or 2 photons at specific detectors (abstract). With such a cheap detector now available (as well as decent photon guns), we could see dramatic progress in this field in the coming months."

Comments

Back in my day

[UnknowingFool]

You kids and your fancy diodes. Back in my day we counted photon by hand. Some people used paper to record the counts. We called them amateurs. Now get off my lawn!

Re:Back in my day

[Anonymous Coward]

You had hands AND a number system? You lucky bastard.

Re:Back in my day

[JustOK]

I had to make photons on my first day and I saw it was good.

Re:Back in my day

[A beautiful mind]

Oh, hello Big Bang, nice to meet you!

Re:Back in my day

[h4rm0ny]

Yet your uid is only 667959! Man, that must make some people round here old! ;) :)

Re:Back in my day

[m.ducharme]

So you didn't have problems with workers stealing your photons?

Is it legal in Florida?

[140Mandak262Jamuna]

I mean if multiple photons arrive at the same time at the detector should they be counted as a single vote or multiple votes? Whatever you say someone or the other would object and eventually it will be decided in the Supreme Court. Counting is quite weird in Florida.

Re:Is it legal in Florida?

[JamesP]

You see, it depends on the wavelength of the photon.

If they are red they may be counted multiple times

If they are blue, counting is more difficult, and sometimes several pass without being counted

A Fiat 500 into a Ferrari?

[FlyingSquidStudios]

So it turns something cheap and unreliable into something most people can't afford that doesn't perform well in crashes?

Re:Down already?

[courteaudotbiz]

1. Check your internet connection
2. Post on slashdot that the site has been slashdotted ONLY if your internet connection was working on step one

Re:Down already?

[torkus]

While I can get to the site...I have to question your logic.

Unless /. has some new magics you generally can't post HERE without an active internet connection.

Re:Down already?

[jddj]

Actually, your attempt to read the site caused its superposition to decay into a site that's Slashdotted.

About 50% of visitors from Slashdot will see the non-Slashdotted site.

Re:Ferrari? Not quite

[Bluesman]

That's no joke. I was going to buy a photon counter for my wife and I to share, but now, I'm going to buy about ten of these for each of us, just in case of a hurricane or something.

Hopefully economies of scale will kick in once these hit the Best Buy shelves.

A Fiat 500 into a Ferrari?

[Fantastic Lad]

What a strange analogy.

[. . .] the original Fiat 500, launched in 1957, still holds a place in the heart of most Italians similar to the original Mini for the Brits, the Citroën Deux Chevaux for the French, or the VW Beetle for the Germans (and many North Americans, too).

Cinquecento was really the car that put Italy on wheels. In short, it's a cultural icon.

[. . .]
The original's 500 name came from the displacement of the air-cooled, rear-mounted two-cylinder engine. Slow? Oh my dear God yes.

But cute as a bunny and tough as nails. You still see these collector's items in every Italian city. I'd have one in a heartbeat.

  --Some car magazine.

I wonder if a classic car buff would really want to convert their beloved collector's piece into a modern consumerist status symbol for power and wealth?

In any case, while one is fast, and the other is slow, the Fiat was originally made small so that it could navigate the teeny one-lane streets featured in many Italian cities, whereas the Ferrari needs some serious hubcap room. It could be argued that the analogy should be reversed since the smaller car is more agile and able to deal with small details whereas the other cannot and is in fact primarily focused on flying through as many kilometers as quickly as possible and isn't terribly concerned with counting them off in smaller quantities.

Of course, this kind of observation is the reason why I would be irritating at parties. Carry on. I'm listening.

-FL

Thank you!

[4D6963]

That's like turning a Fiat 500 into a Ferrari

Ha, thank you, dear Slashdot editor, for inserting a necessary car analogy here! As you rightly guessed, it came right at the point in the summary where my feeble mind wondered "huh?!? photon avalanche wtf???".

Thanks to your enlightening analogy my next thoughts were "ha, a Ferrari, of course! So this has nothing to do with the dangers of skiing on beams of light!", at which point I decided to stop reading the summary as these few concise words seemed to synthesise perfectly the very essence of this discovery, and that my mind proceeded to wander about how awesome it would be to be able to ski on waves of light!

Thank you a thousand times, oh most esteemed and wise Slashdot editor!