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Fighting Counterfeiters With Quantum Money

Soulskill posted more than 2 years ago | from the simultaneously-rich-and-poor dept.

The Almighty Buck 149

the_newsbeagle writes "This article discusses a proposal to create cash that can't be counterfeited by embedding quantum particles in banknotes. A counterfeiter trying to copy a real bill would have to precisely measure all the attributes of the embedded quantum particles — which is impossible under the tricky laws of quantum mechanics (PDF). MIT computer scientist Scott Aaronson, who famously offered a prize for anyone who could prove quantum computers are impossible, said, 'This is science fiction, but it’s science fiction that doesn’t violate any of the known laws of physics.'"

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149 comments

Definitely science fiction. (1)

Anonymous Coward | more than 2 years ago | (#40224653)

The day that we are able to control quantum decoherence and noise in currency that goes through a washing machine will be a great day. But I can assure you this is so far in the future economics will be a completely different creature, almost certainly not concerned with currency.

Definitely Science Fiction from 1970 (1)

eldavojohn (898314) | more than 2 years ago | (#40224787)

I can't remember where I read about this, I believe it was Simon Singh's The Code Book but anyway this was first proposed as far back as 1970 by Stephen Wiesner [wikipedia.org] . It's sort of odd that it reappears every now and then.

Re:Definitely science fiction. (-1)

Anonymous Coward | more than 2 years ago | (#40225913)

Why do we need Quantum money when we've got 1 cent coins. With digital transactions we can go smaller, but quantum currency isn't necessary.

Sooo (5, Interesting)

ae1294 (1547521) | more than 2 years ago | (#40224659)

What happens when someone needs to look at the money to verify it's not counterfeit?

Re:Sooo (0)

Anonymous Coward | more than 2 years ago | (#40224685)

Quantum. Obviously.

Obligatory bitcoin reference (1)

Anonymous Coward | more than 2 years ago | (#40224773)

Or you can just use bitcoin.

let's be honest here... (4, Funny)

Thud457 (234763) | more than 2 years ago | (#40225119)

Maybe I'll pay you Tuesday for a hamburger today.

Re:Sooo (5, Funny)

girlintraining (1395911) | more than 2 years ago | (#40224699)

What happens when someone needs to look at the money to verify it's not counterfeit?

They get a cat that might be alive.

Re:Sooo (1)

icebike (68054) | more than 2 years ago | (#40224905)

Excellent. A security measure that leaves counterfeit bills intact, and renders real ones useless.
And when I drown my sorrows over these feline cadavers at the corner bar, the barkeep will tell me my
money is worthless. New meaning to the phrase dead cat bounce.

Re:Sooo (2, Funny)

Anonymous Coward | more than 2 years ago | (#40225011)

I thought we settled it yesterday that you could just take the dead cat and turn it into a helicopter to raise money.

Re:Sooo (1)

operagost (62405) | more than 2 years ago | (#40225181)

Once I get my mouse-o-copter and dog-o-copter off the ground, I plan to recreate every Tom and Jerry cartoon with live aerial action.

Re:Sooo (1)

g0bshiTe (596213) | more than 2 years ago | (#40225349)

No that's raising dead cats, he didn't have any money on that copter.

Re:Sooo (1)

DigiShaman (671371) | more than 2 years ago | (#40225625)

I have one that might be dead.

Re:Sooo (1)

Tanman (90298) | more than 2 years ago | (#40225667)

At the very least it is possible that it might not have been dead anymore . . .

Re:Sooo (1)

Anonymous Coward | more than 2 years ago | (#40224753)

The idea is that each particle can be measured in multiple dimensions. One person can measure any one, but not all three. The bank will have a listing for each bill of which dimension to measure and the expected result. Each bill will have a large number of quantum particles to prevent matching by chance.

This setup is only as secure as the database holding the recording for the bill.

Re:Sooo (1)

vlm (69642) | more than 2 years ago | (#40224995)

Breaks down to a OTP scheme? Just use scratch off lotto ticket technology?

One person can measure any one, but not all three.

This I'm fuzzy on. Only 3 like an old digicash protocol but with only 3 sigs, or 3 as in like 3 dimensions or something?

Re:Sooo (2)

hajus (990255) | more than 2 years ago | (#40226169)

You can measure the bit in 1 of 3 dimensions. Let's say the bank measured it in dimension x out of x, y, and z. Now if you want to measure it, you can measure it in any of those dimensions. If you measure in x, you don't mess it up, but if you measure in y or z, you mess up the x reading and it gets randomized. Now if you have 64 bits, then you have to guess all 64 dimensions correctly, or you'll mess something up just by measuring it in a different dimension than what the issuing bank measured. Now all the bank has to do is record which dimensions the bill was measured in and what they got 0, or 1. If someone tried to measure it or made a fake one, then the bank will see all wrong numbers, either scrambled because of wrong measuring, or wrong because whoever issued the fake currency put in different random settings.

Re:Sooo (1)

FatdogHaiku (978357) | more than 2 years ago | (#40225149)

What happens when someone needs to look at the money to verify it's not counterfeit?

You can know how much you have, or where it is, but not both.
Looking at it changes it
If you look at a counterfeit it will remain unchanged.
Don't stare at your 401k...

Re:Sooo (1)

Hatta (162192) | more than 2 years ago | (#40225233)

Before you look at it, it's in a quantum superposition of counterfit and authentic states. Looking at the bill collapses that superposition into being actually counterfit or authentic.

Re:Sooo (1)

ae1294 (1547521) | more than 2 years ago | (#40226055)

Before you look at it, it's in a quantum superposition of counterfit and authentic states. Looking at the bill collapses that superposition into being actually counterfit or authentic.

Let me guess, it always collapses into the counterfeit state...

Quick question (0)

Anonymous Coward | more than 2 years ago | (#40224671)

If a counterfeiter can't measure it to duplicate it...
...then how can the authorities measure it to verify it?

Re:Quick question (1)

istartedi (132515) | more than 2 years ago | (#40224695)

They'll issue you a new quantum note when they verify the old one.

Re:Quick question (0)

Anonymous Coward | more than 2 years ago | (#40224735)

So... wouldn't bit coins just be easier?

Re:Quick question (2)

Quantus347 (1220456) | more than 2 years ago | (#40224767)

Sure because bitcoin is so very secure

Re:Quick question (0)

Anonymous Coward | more than 2 years ago | (#40225099)

Has a bitcoin ever been counterfeited? Bitcoins get stolen just as cash gets stolen, I think it's a bit unfair to call bitcoin insecure just because some people can't be bothered to store them in a secure manner.

Re:Quick question (0)

Anonymous Coward | more than 2 years ago | (#40226295)

https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures#CVE-2010-5139

Re:Quick question (1)

gox (1595435) | more than 2 years ago | (#40225475)

They've never been counterfeited, if that's your point. Otherwise I guess quantum money can still get stolen, just as your bitcoins can.

You'll still get upvotes for satirizing Bitcoin though, don't worry.

Re:Quick question (2)

X0563511 (793323) | more than 2 years ago | (#40225559)

Lets be fair: it could be possible this is because it's so much easier to break in and steal them, then work out how to fake them. This doesn't mean it's impossible to do.

Re:Quick question (1)

gox (1595435) | more than 2 years ago | (#40226061)

Yeah, quantum money would be impossible to counterfeit. Counterfeiting Bitcoin is not against the rules of the universe. I'm not claiming it is as secure or something to that effect, actually I don't claim anything.

However, the commentor implied that Bitcoin is not so secure, which requires some knowledge about how it can be counterfeited. If I claim right here that SSH is not so secure, would you upvote me?

Re:Quick question (1)

istartedi (132515) | more than 2 years ago | (#40224897)

Actually, the real problem is that while "the authorities" can work around this by issuing a new note, a person at a cash register can't. You don't want every clerk to have the power to create money. This is less of a problem if the money is digital, sent to a central authoritative server for verification, destroyed there, and re-issued. Then the clerk doesn't have the power to create money; just the central authority. Yep, it's easier if the whole thing is digital; although probably not BitCoin (TM).

The problem is also solved if the "note" is actually a little computer with qbits on it. Then the money is in the bits, not the little computer itself. You can send the bits to the central authority, destory, replace, etc.

Re:Quick question (1)

vlm (69642) | more than 2 years ago | (#40225089)

Then the clerk doesn't have the power to create money

Its a lot simpler if they do. When I was a kid working at the supermarket we did not modify gift certificates we printed and issued new ones, and the old ones were put into a file and presumably shredded after some time (not my department). This was... some time ago, they don't do it this way anymore, at least partially because we only accepted our store certs and were our own mint, and now a days they like nationwide gift cards/certs.

Simply have the kid at the counter shove "used" $20 bills into a lockbox that magically spits out a newly minted $20 in exchange. Hard to do mechanically in real life, but I assume it woundn't be too much more expensive than an ATM.

Basically make what a chem eng would call a low latency continuous process instead of a ultra high latency batch process.

Re:Quick question (1)

dgatwood (11270) | more than 2 years ago | (#40225341)

No need to remake the bill. Just provide a cash register that can communicate with the verification database and update tokens. Upon proving that it actually has the bill (by providing its serial number and the values read from these quantum particles), it could then upload a new signature for the bill representing whatever state it left the quantum particles in. The signature in the database would be different, but still trusted.

Re:Quick question (0)

Anonymous Coward | more than 2 years ago | (#40226043)

Nope. That currency wouldn't be divisible if you didn't have a network connection. You could exchange tokens, but what if your token had $500 and the item only cost some fraction of that? If your not going to make the system work for people who don't have network connections, you're giving them an official de facto "do it off the books when the network is down or if you live far enough north." Maybe that's not enough to worry about but it definitely wouldn't be legal. So what you'd really need is each cash register have the ability to mint new cash (onto the customers token) when provided with said token... I think our current system is better and probably harder to hack.

Re:Quick question (1)

X0563511 (793323) | more than 2 years ago | (#40225585)

So why not issue credit "chits" that contain the bits describing the money, and not individual notes?

Kind of like the debit cards we have now. But instead of a relatively short ID number, they have a quantum fingerprint?

So... (0)

Anonymous Coward | more than 2 years ago | (#40224689)

...checking to see if the note is a fake?

This sucks at the point-of-sale (5, Funny)

Anonymous Coward | more than 2 years ago | (#40224723)

Where they have to use cats instead of the much simpler counterfeit checking pens.

This will be a profit loser and allergic shoppers will suffer in particular.

Re:This sucks at the point-of-sale (1)

Rockoon (1252108) | more than 2 years ago | (#40224755)

Where they have to use cats instead of the much simpler counterfeit checking pens.

The useless pens that do nothing but test for starch? Yeah... cats really are just as effective.

Re:This sucks at the point-of-sale (2, Funny)

Anonymous Coward | more than 2 years ago | (#40225479)

Actually, they test for cocaine residue.

Re:This sucks at the point-of-sale (0)

Anonymous Coward | more than 2 years ago | (#40224931)

Where they have to use cats instead of the much simpler counterfeit checking pens.

This will be a profit loser and allergic shoppers will suffer in particular.

I read that as counterfeit checking penis.

Schrodinger's Money (4, Funny)

Daetrin (576516) | more than 2 years ago | (#40224741)

You never know if you still have any left until you open your wallet to check.

Re:Schrodinger's Money (4, Funny)

plover (150551) | more than 2 years ago | (#40224823)

You never know if you still have any left until you open your wallet to check.

I've got matrimonial money. I don't have to open my wallet to know my wife has it all.

Re:Schrodinger's Money (1)

Beardo the Bearded (321478) | more than 2 years ago | (#40224943)

You never know if you still have any left until you open your wallet to check.

I've got matrimonial money. I don't have to open my wallet to know my wife has it all.

Huh, my wife and I have separate bank accounts. We split up the bills so it comes out about even afterwards.

Re:Schrodinger's Money (1)

Anonymous Coward | more than 2 years ago | (#40225275)

Cool story, bro.

This article was written by an idiot (1)

Cyberax (705495) | more than 2 years ago | (#40224761)

This article was written by an idiot. You can't measure all the properties of a quantum particle. But so what? You can't exploit it unless you have entangled particles. And it'll be a bit complicated to store your banknotes in total isolation from the environment.

Re:This article was written by an idiot (1)

jeffmeden (135043) | more than 2 years ago | (#40224851)

This article was written by an idiot. You can't measure all the properties of a quantum particle. But so what?

You can't exploit it unless you have entangled particles. And it'll be a bit complicated to store your banknotes in total isolation from the environment.

You might as well assume that since they mentioned Science Fiction, that nanotubes (perhaps of the graphene variety) are going to be involved here. That pretty much solves everything, so what is it that you are so worried about?

Re:This article was written by an idiot (0)

Anonymous Coward | more than 2 years ago | (#40225145)

This article was written by an idiot. You can't measure all the properties of a quantum particle. But so what?

You can't exploit it unless you have entangled particles. And it'll be a bit complicated to store your banknotes in total isolation from the environment.

You might as well assume that since they mentioned Science Fiction, that nanotubes (perhaps of the graphene variety) are going to be involved here. That pretty much solves everything, so what is it that you are so worried about?

It's simpler than that even. It's going to involve the use of non-dairy creamer in a microwave. However, it does run some risk of turning a person into a talking mouse.

Why bother with the technobabble? (2)

Powercntrl (458442) | more than 2 years ago | (#40224775)

If you're tracking the serial numbers of a bill in a database, skip the quantum brainhurt and just do the same thing video game authors and cell phone companies do: make sure the serial number isn't being used in more than one place at a time. Duh.

Seriously, it's like trying to invent a phaser so you can light a campfire, when the rest of us would just use a match.

Re:Why bother with the technobabble? (1)

jeffmeden (135043) | more than 2 years ago | (#40224903)

If you're tracking the serial numbers of a bill in a database, skip the quantum brainhurt and just do the same thing video game authors and cell phone companies do: make sure the serial number isn't being used in more than one place at a time. Duh.

Seriously, it's like trying to invent a phaser so you can light a campfire, when the rest of us would just use a match.

Really. Really? Simply make sure that a certain marking only exists in one place? I suppose you could, in theory, require every single transaction of currency to involve scanning the numbers, then checking the numbers in with a central authority who knows that certain numbers have been sent from shopper to merchant and need to be "re-authorized" for shopper use again. Otherwise I could run off a thousand copies of a single bill and just use them over a few weeks' time and no one would be the wiser. However with this "improved" system every single transaction will be tracked electronically to eliminate counterfeits (or was that guy we just arrested carrying the originals?) Yep what could possibly go wrong.

what about remote areas??? (1)

Joe_Dragon (2206452) | more than 2 years ago | (#40225069)

what about remote areas??? some cash register systems may run the tapes overnight. But tieing up the phone for each transaction??

What about satellite internet that has lag, small bandwidth and rail fade.

Re:what about remote areas??? (1)

vlm (69642) | more than 2 years ago | (#40225215)

what about remote areas??? some cash register systems may run the tapes overnight. But tieing up the phone for each transaction??

What about satellite internet that has lag, small bandwidth and rail fade.

This kind of stuff was figured out for digital cash in the 90s. Look up a dude named Chaum (maybe misspelled) and his digital cash protocols. If you know how SSSS works and think about signing a note 100 times not once when you "spend" and think about zero knowledge proofs then you're about 90% of the way there already.

"Oh so this is why a digital $20 bill requires 10 megs of memory"

Re:Why bother with the technobabble? (1)

Threni (635302) | more than 2 years ago | (#40225157)

The checking technology sort of exists - credit cards.

If cash had a random element (a second serial number, for example, with no connection to the first, which would be sequential) then the counterfeiters would have to have the original notes to copy. Otherwise they'd fake it, and when the note was used it would be checked against the database and be shown to be obviously wrong (note 1049242 should have a security number of 194, this one has 188).

Re:Why bother with the technobabble? (0)

Anonymous Coward | more than 2 years ago | (#40224927)

Except with the slight miniscule flaw of the untracked ownership changing hands with every transaction which isn't the case with "cell phones companies" and software.

You have how many slices of time in a day? Think about it. Just going to assume that someone using the note in one state can't be using it in another state?

Going to do the mathematical distance calculations and deal with the consumer backlash whenever their bills are coming up as "counterfeit" because your math didn't account for every situation?

btw: Duh.

Or... (0)

Anonymous Coward | more than 2 years ago | (#40224803)

We could make all transactions digital and use quantum cryptography (which is being studied pretty closely already).

Huge upfront cost (2)

Quantus347 (1220456) | more than 2 years ago | (#40224825)

This is one of those things that might well work in a limited situation (tracking marked bills to reveal criminal activity, etc) but the cost of Encoding, recording, and (securely) logging every bill as it is printed just isnt something that would be feasible for the majority of bill denominations. Maybe if it was limited to large quantity bills or something...

Re:Huge upfront cost (0)

Anonymous Coward | more than 2 years ago | (#40225599)

This is more of a hypothetical currency like bitcoins. People can't duplicate the sequence without knowing how to measure it. This makes the sequence impossible to duplicate unlike the current serial numbers on paper bills. The actual paper bill isn't important. This is more significant in secure quantum communication and the currency idea is more of a side thought. Unfortunately the whole story is above the people on /. since it doesn't involve computers/software and most of the comments will be stupid "I don't get it. I'll just make a joke for that area of science." comments.

Re:Huge upfront cost (0)

Anonymous Coward | more than 2 years ago | (#40225993)

This also raises the question of how cash automation systems would adapt to theses changes. It seems like a very expensive solution to a problem that is somewhat being addressed with polymer + windowed bills. What is interesting is that the technology available now cannot be "too accurate" at detecting counterfeit bills, this is limited by a % threshold determined by the Federal Reserve. That could be because it's possible there are more counterfeit bills in circulation than anyone wants to acknowledge. I think it would be interesting to see how someone would approach validating an "un-counterfeitable" bill, but also very unnecessary.

Posting anonymous coward for obvious reasons.

As opposed to those electrons,protons,&neutron (1)

Guy Harris (3803) | more than 2 years ago | (#40224841)

As opposed to all those non-quantum electrons, protons, and neutrons embedded in there now, presumably....

From TFA:

The visionary physicist Stephen Wiesner came up with the idea of quantum money in 1969. He suggested that banks somehow insert a hundred or so photons, the quantum particles of light, into each banknote. He didn’t have any clear idea of how to do that, nor do physicists today, but never mind. It’s still an intriguing notion, because the issuing bank could then create a kind of minuscule secret watermark by polarizing the photons in a special way.

So it's not as if this is some idea that people actually know how to implement....

Uncertainty (0)

Anonymous Coward | more than 2 years ago | (#40224855)

Does this mean that you can either know how much cash you have, or where your wallet is, but not both?

Gold (1)

detritus. (46421) | more than 2 years ago | (#40224867)

I'll stick with gold, thanks.

Re:Gold (1)

betterunixthanunix (980855) | more than 2 years ago | (#40224977)

Yeah, nothing like a currency that doesn't scale with a growing population...

Re:Gold (1)

operagost (62405) | more than 2 years ago | (#40225227)

That's kind of the basic principle of currency: scarcity. But now we listen to Keynesian bankers who control our wealth.

Re:Gold (0)

Anonymous Coward | more than 2 years ago | (#40225571)

Fiat currency came about long before Keynes's theories... The underlying basis of Keynes' theory came about before he did, too, at least with regards to governments financing their wars.

Re:Gold (0)

Anonymous Coward | more than 2 years ago | (#40225235)

I agree, it would be utterly horrible if money actually increased in value over time. Thankfully, knowing that the federal reserve can create as much money as they need to and that my life savings will be utterly worthless by the time I need it gives me comfort in these uncertain times.

Re:Gold (3, Insightful)

betterunixthanunix (980855) | more than 2 years ago | (#40225521)

I agree, it would be utterly horrible if money actually increased in value over time.

Spoken like someone who has never had to repay a loan...

Re:Gold (1)

geekoid (135745) | more than 2 years ago | (#40225231)

Five little words to inform the world you know nothing about economics.

Re:Gold (1)

kwiqsilver (585008) | more than 2 years ago | (#40226035)

Yeah, because it's not like gold* has been the most stable currency in human history...oh...wait...it has.
But there's no way that gold* has been the currency during every era of growth and prosperity, while fiat currency has been the currency during every economic collapse...what? That's true too? Really?
Well, I'm sure if we keep up the strawman attacks on the "kooky gold hoarders", people will continue to use fiat currency until we've successfully transferred all of their wealth to banking elites. And that's what's matters.

*Gold is used here to generically mean precious metals, primarily gold and silver, or certificates representing actual precious metal.

Re:Gold (1)

DMUTPeregrine (612791) | more than 2 years ago | (#40226583)

Gold hasn't been particularly stable, since the value of gold is determined by what various countries set it at. EG in 1934, the U.S. government revalued gold from $20.67/oz to $35.00/oz, instantly deflating the dollar.

Every economic collapse, eh? Clearly the Roman Empire used fiat currency! Also, the crash of 1929 was in no way whatsoever caused by the use of a gold standard. Finally, there have been quite a number of eras of growth and prosperity in which gold was not the standard. EG After WW2 Britain ended the gold standard and started an era of significant technological and economic growth.

"Kooky gold hoarders" are rather silly, because they tend to ignore any evidence that contradicts their views. There are many more counterexamples to the points you listed, and they aren't terribly difficult to research.

Re:Gold (0)

Anonymous Coward | more than 2 years ago | (#40226187)

Five little words to inform the world you know nothing about economics.

Economics?

Isn't that the science where theories are used to refute reality?

Confirmation (-1)

Anonymous Coward | more than 2 years ago | (#40224881)

"A counterfeiter trying to copy a real bill would have to precisely measure all the attributes of the embedded quantum particles..."

Unfortunately, anyone attempting to confirm the authenticity of a bill would need to do the same, which makes this suggestion bunk on its face.

I was a quantum millionaire (1)

Anonymous Coward | more than 2 years ago | (#40224891)

I had a wallet stuffed with a quantum money all in a superposition. Unfortunately when I went to a car dealership to buy a Porche cash, the wavefunction of my cash collapsed into a dirt poor eigenstate and I was left destitute and penniless.

(FYI This is also how stock markets work)

Cant be counterfeited (1)

nurb432 (527695) | more than 2 years ago | (#40224929)

And cant be anonymous. Besides if it can be created it can be copied. Its just a matter of making the cost of entry too high to be worthwhile.

OTP digital cash (1)

vlm (69642) | more than 2 years ago | (#40224971)

Looks like someone read one of Chaum's old blind signature scheme papers and some zero knowledge proof papers from the early 90s, then thought it would be cool to store the bits as quantum states instead of flash memory or bar codes (why?) and it got rammed thru a journalist filter to totally screw up the protocol.

If that is the case, its really important that unlike the journalists interpretation of the protocol, you have like 200 sigs and only break 100 to prove they're all probably real. That is, if 100 randomly selected sigs work then you know you've got 2**100 odds that its all legit (um, more or less) and you have no idea whats stored in the other 100 sigs but they're probably real sigs. But if you double spend, then enough SSSS shares will be unlocked (well, maybe all of them will be unlocked depending on scheme) to identify the double spender.

This cash idea in the above article would only work if each bill was spent precisely once before being returned to be reminted. Not unlike a gift card.

Oddly enough a complete digital cash protocol cannot be completely correctly described in one little /. post. But the TLDR version is something like:
1) A piece of cash doesn't get one sig it gets like 500
2) If you want 2**64 odds that its not fake, after you collect the 500, you make the other guy break your random choice of 64 of the sigs, leaving 500-64 good unbroken ones.
3) If you double spend a lot of mathematical tomfoolery (usually SSSS based) magically cracks enough sigs to figure out the double spenders name. This is actually the hard part.

Probably 10 years ago I did a 15 minute demo in a classroom of Chaum's digital cash system, with some major (huge) simplifications, using something like a whole box of thank you notes and envelopes (walmart to my rescue). I thought it was "old" at the time since it was more than half a decade old. I donno if there is anything newer/better or interesting results since then, haven't kept up. You still need a mint for every transaction, you just don't need a LIVE connection to the mint for every transaction, as I recall. I remember it was a PITA sealing and tearing up all my envelopes, and the prof liked my topic and liked my prop but it was a little slow paced for a good demo. And I remember I got a paper cut. Oh well.

Make American dollars more sophisticated (2)

swb (14022) | more than 2 years ago | (#40225001)

Besides a slight cut in seigniorage, why don't they make American dollars more difficult to counterfeit? Using materials, colors, etc that would only allow the most skilled counterfeiters (ie, North Korea or other groups with state backing) to copy them?

A lot of foreign currency has different sizes of bills, little plastic windows, metallic inks (or it could be mylar) and so on that would be extremely challenging.

I know they've tried to make American money more difficult to counterfeit (micro-printing, watermarking, etc) but it seems like people just keep bleaching out the ink and turning $1s into $20s or $100s because its so darn easy, which in turn makes it easier for the pros to turn out really good fakes, especially overseas.

It's almost enough to make a guy put on his tin hat and try to think up reasons why the government would WANT the currency counterfeited, especially overseas where it would have less impact on the native dollar economy but keep the currency supply large enough to maintain dollar-as-defacto-currency status...

Re:Make American dollars more sophisticated (5, Informative)

operagost (62405) | more than 2 years ago | (#40225283)

This is a list of all the anti-counterfeiting measures in US currency. People still take fake bills because they just don't bother to check.

        Fiber Embedded Paper. The paper used to print our currency has tiny threads of fibers embedded into the paper. If the bill has no tiny fibers of red and blur embedded into the paper, it is probably a fake bill. Embedding fibers into the paper is one of anti-counterfeiting measures used to make it harder to make fake currency.
        Border Scroll. On the edges of a bill are fine lines in a scroll shape. The thin, fine lines are sharp and clear on an authentic bill. If you try to use a scanner and printer on your home computer to print your own money, the border art will appear blurry and the lines will run together.
        Security Thread. A security thread is embedded into the paper money and runs from the top to the bottom of the bill. It is printed with the currency amount. When held over an ultraviolet light the security thread will glow red. The security thread is one of the ten anti-counterfeiting measures that work the best to stop people from making fake money and devaluing our currency.
        Color Shifting Ink. On the $100 bill, a color shifting ink made with metallic flakes is used. On the $100 logo, the ink color will shift from black to green depending on the angle you are holding the bill.
        Microprinting. Microprinting involves printing in such a tiny font that it simply appears as solid lines but when viewed under magnification you can read the printing. Microprinting is an ant-counterfeiting measure that makes it extremely hard, if not impossible, for the average person to print fake money at home.
        Serial Numbers. Printing serial numbers on currency makes it harder for counterfeiters to forge fake money. In a large batch of fake currency, the counterfeiters may be forced to use the same serial number on all the bills making it easier to spot the fake bills. On fake bills, the serial numbers may not be evenly spaced or sized which is a dead give away that the bill is fake.
        Watermark. A watermark is embedded into the paper during the actual process of printing the paper. A watermark is very hard if not impossible for most counterfeiters to accurately replicate. A watermark is one of the ten anti-counterfeiting measures used to easily distinguish real currency from fake currency.
        Paper Color. The Yellow and Greenish colored hues used paper money makes bills hard to duplicate at home. A counterfeiter will have a hard time trying to duplicate the color scheme of an actual bill.

most US currency is interest-free Treasury-bond (1)

peter303 (12292) | more than 2 years ago | (#40226109)

In normal economic times this is a profit center for the US Treasury. Long term rates are historically 4%. Instead of the treasury paying $40 for a 10-year bond, it pays nothing for the equivalent currency as long its is never returned to the Reserve Bank for one reason or another. That is the advantage of being the world's most popular cash currency. Something like $700B fr the $1000B in cash never returns to US banks.

Re:Make American dollars more sophisticated (1)

vlm (69642) | more than 2 years ago | (#40225327)

Hard as it might be for end users to believe, most "dollars" are electronic not paper, so any foolishness going on with paper doesn't really matter in the big scheme of things. Actually, a foreign country spending "new" dollars to import american products is not so bad of a thing.

Re:Make American dollars more sophisticated (0)

Anonymous Coward | more than 2 years ago | (#40225451)

Every attempt to make it hard to counterfeit money also makes it more expensive to produce.

bill validators need to have this tech (1)

Joe_Dragon (2206452) | more than 2 years ago | (#40225021)

bill validators need to have this tech but outside of slots they will likely cost to much to put in.

how to authenticate? (1)

amigabill (146897) | more than 2 years ago | (#40225113)

A counterfeiter trying to copy a real bill would have to precisely measure all the attributes of the embedded quantum particles — which is impossible under the tricky laws of quantum mechanics (PDF).

OK, so how does this help to authenticate a genuine note?

Re:how to authenticate? (1)

dgatwood (11270) | more than 2 years ago | (#40225537)

You have multiple properties and you cannot copy all of them because when you read one of them, it changes the others. If the verifier chooses to verify the property that the forger copied, your fake passes. If it chooses to verify one of the other properties, your fake is rejected. Therefore, if each bill has a bunch of these quantum particles and the verifier chooses which property to evaluate randomly, odds are any copied bill will fail. (Of course, you probably also have to allow a certain percentage of failures to prevent false rejections, which may or may not make this approach impractical.)

Verification does, as others have mentioned, destroy the quantum state of the particles, but that's a separate (and easily solvable) problem.

wow (0)

Anonymous Coward | more than 2 years ago | (#40225185)

Wow, and people said Bitcoin was impractical and ridiculous...

Great news! (1)

partiklehead (2425806) | more than 2 years ago | (#40225193)

Finally money will be worth the paper it's printed on. Oh wait.

Ehh... (1)

king neckbeard (1801738) | more than 2 years ago | (#40225259)

I think we just need to go back to latinum based currency

Wrong area (1)

wisnoskij (1206448) | more than 2 years ago | (#40225263)

Practically, we do not have a problem with perfect counterfeits that simply cannot be spotted by an expert. In fact we already have an infallible system (serial numbers: we know all the bills in existence and if any duplicates turn up or numbers out of range we know that counterfeiting is going on and that those bills are counterfeit).

The problem with counterfeiting we actually have is that bills can relatively easily get past retailers and allow the owner to purchase stuff or launder it even if they would fail to pass scrutiny.
This, if you consider it a big problem, could be solved with current technology and current bills (all bills get scanned and the serial number verified).

Conclusion does not follow ... (0)

Anonymous Coward | more than 2 years ago | (#40225291)

Bank notes already have embedded quantum particles.

Re:Conclusion does not follow ... (1)

mj1856 (589031) | more than 2 years ago | (#40226029)

That's what I was thinking... EVERYTHING contains quantum particles. What makes bank notes any different? Besides, as others have pointed out - how would you verify them?

Storing Photons (1)

Anonymous Coward | more than 2 years ago | (#40225313)

Is it even possible to store a photon? You can capture a photon. You can scatter a photon. I don't think you can store a photon.

And really, how do you keep the secret watermark a secret? Once the spec document for the watermark is written, someone will need to make the watermark verifying equipment. And once that equipment is made, it will be sold to someone who is not to be trusted.

Counterfeit (-1)

Anonymous Coward | more than 2 years ago | (#40225319)

The problem with this solution is the counterfeiter is the US government printing the paper money. We should just return to gold and silver.

Re:Counterfeit (1)

ka9dgx (72702) | more than 2 years ago | (#40225595)

The use of a portable XRF (Xray Fluorescence) scanner can quickly determine if money has been debased or not.

This article is about currency, which is a promise of money.

I've been using quantum currency for years now. (1)

BronsCon (927697) | more than 2 years ago | (#40225527)

My bank balance is both positive and negative until I observe it. I simply never observe it. The positive side usually wins.

The six billion dollar $20 bill (2)

Narrowband (2602733) | more than 2 years ago | (#40225587)

When it costs eight or nine orders of magnitude more to produce the money than the face value of the money itself, that's generally regarded as a design flaw. It's a sure bet that you could absorb a whole heck of a lot of losses from counterfeiting for the cost of inventing new quantum particle manipulation and testing technologies and distributing them throughout a banking/finance system. By the time it pays for itself, you'd need to have currency that can survive commerce via warp drive.

Separate point -- even if the physics don't preclude the whole concept, what do you want to bet you couldn't do the testing in a non-destructive manner (i.e., without affecting the properties of the quantum particles). "Well, it WAS a real $20 bill. Oops."

Time Tunnel Tech Still Good Enough (0)

Anonymous Coward | more than 2 years ago | (#40225745)

Radiation-tag them, like the time-tunnel did. As an aside, it could also discourage hoarding.

I think I can take advantage of this. (1)

Anonymous Coward | more than 2 years ago | (#40225759)

Clerk: That'll be $57.50
Me: This should cover it.
Clerk: Sir, this is a $1 bill.
Me: Well it was a $100 bill before you looked at it.

I've got a better idea (1)

midtowng (2541986) | more than 2 years ago | (#40225829)

How about using gold for money? We already know that it can't be faked, and there are simple tests to see if it is real. Plus there that thing about thousands of years of a solid track record as money.

Re:I've got a better idea (0)

Anonymous Coward | more than 2 years ago | (#40225929)

How about using gold for money? We already know that it can't be faked, and there are simple tests to see if it is real. Plus there that thing about thousands of years of a solid track record as money.

Dense. Attempts to send gold from New York to Sydney in less than 0.025s have been problematic.
Fickle. Supply curve highly sensitive to changes in mining technology.
Lame.

"assume a spherical cow" type-article (1)

peter303 (12292) | more than 2 years ago | (#40225879)

These theory guys would be totally helpless in the real world.

Those in debt rejoice.. (1)

wbr1 (2538558) | more than 2 years ago | (#40226009)

Bill collector: Did you send payment?
Debtor: Yes. Well, at least partial payment.
Bill collector: What do you mean partial?
Debtor: I am not sure. I can tell you when the money will arrive, but not how much it is, or I can tell you how much I paid, but not when it will get there. Your choice.
Bill collector: *facepalm*

Only works when only banks know how to do it (0)

Anonymous Coward | more than 2 years ago | (#40226381)

The whole reason this is supposed to work is because, from the article:

"Thanks to the no-cloning theorem, a counterfeiter couldn’t measure all the attributes of each photon to produce a copy. Nor could he just measure the one attribute that mattered for each photon, because only the bank would know which attributes those were."

That is ridiculous on its face, because how is the bank going to keep that secret? How do people that aren't banks check the validity of a given note? If you want to prevent counterfeiting, you just have to make the notes prohibitively expensive to counterfeit. Once you kill the profit motive, you're set.

Science Fiction vs Fantasy (0)

Anonymous Coward | more than 2 years ago | (#40226589)

All Science Fiction doesn't violate the known laws of physics.

Being Scientifically Plausible is what separates Science Fiction from Fantasy.

Please don't be ignorant. This is Slashdot, if there's any bastion of facts about SciFi, we should be it (then again, this is TFS, I shouldn't expect too much).

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