If you had to identify some of the key differences between a genuine £20 note and a fake, how many would you be able to list? Before researching this article, I would have probably been able to identify two: that picture of the Queen that reveals itself when the note is held up to the light and a hologram that I vaguely remember but couldn’t describe in any detail. I am sure that I am not alone in being almost completely ignorant when it comes to counterfeit cash, and the fraudsters use this to their distinct advantage when it comes to cheating the system.
Perhaps it is the apparent ease of cash counterfeiting that makes the thought so alluring to potential criminals. Just sneak that £20 into a scanner and you are good to go, right? It’s not quite that simple, but it is easier than one might have thought, considering the amount of counterfeit money currently in circulation. According to the Co-Operative Wholesale Society “Over the last year, counterfeit money through our stores has jumped 20 per cent”. Although bank notes do have some tricks to make it difficult to produce fake bank notes, such as watermarks and holograms, forgery techniques have become so advanced that it is now impossible to identify many fake notes with the naked eye, even if you know exactly what to look for.
A rather surprising point is that cash counterfeiting is a crime that hits the consumer the hardest. Upon finding a fake bank note, a member of the public is supposed to hand it in to a police station, receiving no compensation… but to pass the note on is considered a criminal offence. In addition to this, a shop is in no way obliged to refund you for a fake note, even if it was given to you straight from their cash register.
Luckily for us, the poor old consumer, a new technology is currently being researched that may make it even tougher for those cash-hungry cons to fake it… and it is all down to a theorem developed in 1982; the no-cloning theorem.
The no-cloning theorem states that it is impossible to create identical copies of an arbitrary unknown quantum state. Translated to English, this basically means that it is impossible to make an exact copy of a quantum particle, as in doing so you have to take measurements from the original particle and this will cause the original particle to change. So once you are through with all your measurements, the particle is no longer the one you started with. This makes it pretty tough to counterfeit.
This theory is still slightly closer to sci-fi than reality, but it is sci-fi that is theoretically possible. If banks were to develop a system that could read just one aspect of the particles quantum state, leaving all other aspects unchanged, then this could be checked against a database to see if the quantum state was as expected.
In the mean time, we can take comfort in the fact that some counterfeit combating devices are already developed and in use. For instance, the ‘Cashguard’ is a device that sits in a cash machine and as a bank note is placed in the till, it is scanned and a sensor is used to determine which wavelengths of light are reflected, and hence determined the validity of the note. This nifty device has been proved to pick out the vast majority of fake notes, keeping our cash clean and our wallets legal.