Home / Opinion / Columns /  Schrödinger’s cat and the worry of a quantum apocalypse ahead
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Let me try distracting you from war and disease with a joke. Schrödinger takes his cat to the vet for a check-up. The vet comes back 10 minutes later and says, ‘Well, I have good news and bad news…..’ If you snickered at this, you know a bit about the Schrödinger’s Cat paradox, and therefore perhaps a little bit about quantum physics. For those who did not, the paradox explains the seeming contradiction between what we see with our naked eye and what quantum theory tells us actually exists in its microscopic state. The ‘Copenhagen interpretation’ of quantum mechanics states that ‘a particle exists in all states at once until observed’. Schrödinger’s cat is in a box, and could be alive or dead. But till the box is opened, you would not be able to know. Thus, the vet’s quandary.

This principle, among others, powers one of the most exciting and bleeding- edge advances in technology: Quantum computing. I have written about it before in Mint, but to summarize: Our current powerful computers follow the principles of the Turing machine, where information is encoded in bits (1 and 0) and a series of operations (and, or, not, etc) make these bits compute. A quantum computer uses qubits or the quantum version of bits; a qubit is not permanently a 0 or 1, but it can be both at the same time. Only at the end of the computation (when the box is opened), can you know whether it’s 0 or 1. During the computation process, its exact state is indeterminate and can contain bits of both. If this whooshed over your head, console yourself with what Bill Gates said in a 2017 interview: “I know a lot of physics and a lot of math. But the one place where they put up slides and it is hieroglyphics, it’s quantum."

A quantum computer can exploit these properties of quantum physics to perform certain calculations far more efficiently and faster than any computer or supercomputer, inspiring the likes of Microsoft, IBM and Google to work feverishly on this form of computing. This is especially urgent because Moore’s Law is flattening but our problems are becoming more complex: climate change, artificial general intelligence, drug personalization. While this is super exciting, a recent BBC article ( ) about the ‘quantum apocalypse’ made me pause.

As a hidden force behind e-commerce, online banking and trading, crypto trading, social networking and internet messaging, almost everything we do involves encryption. Most encryption uses public and private keys, and that in turn uses arcane mathematical calculations involving prime numbers. Using a Turing computer to crack this encryption is virtually impossible. It would take thousands of years. However, a quantum computer can potentially do this in mere seconds. Every minute, huge amounts of encrypted data is harvested without our knowledge and stored in vast data banks, waiting for the day that it can finally be decrypted. Today, there is nothing data thieves can do with this treasure trove, “…but once a functioning quantum computer appears that will be able to break that encryption... it can almost instantly create the ability for whoever’s developed it to clear bank accounts, to completely shut down government defence systems—Bitcoin wallets will be drained." says lyas Khan, chief executive of Quantinuum. Moreover, current encryption methods will be useless, halting online banking transactions, e-commerce, social media interactions, everything. The security of every public blockchain will be under threat from quantum computing power, since it relies on heavy duty cryptography; it was no coincidence that the price of Bitcoin dropped sharply the day Google made its announcement of achieving quantum supremacy a year ago. It was a portent of the quantum apocalypse.

The world is gearing up for this post-quantum world. Google, Microsoft, Intel and IBM are working on solutions. So are specialist startups like Post-Quantum and Quantinuum. The UK government claims that all its top-secret data is already ‘post-quantum’. The BBC talks of a ‘beauty parade’ taking place “to establish a standardised defence strategy that will protect industry, government, academia and critical national infrastructure against the perils of the quantum apocalypse." New cryptographic methods like quantum key distribution are being developed, by which even if the message gets intercepted, no one can read it, much like the cat.

All this will not be cheap, nor will it be easy. But we have no choice—most of our world runs digitally now and its wheels need to be kept humming. To do that, we need to think out of the box.

Jaspreet Bindra is the chief tech whisperer at Findability Sciences, and learning AI, Ethics and Society at Cambridge University.

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