If you’ve ever paid electronically, you’ve used encryption. Encryption is based on large numbers that are the result of the multiplication of prime numbers. A classical computer takes a very long time to reverse that multiplication (or ‘factor’) to get the prime numbers back, which is why encryption is safe. But a quantum computer can factor much faster, and thus break encryption!

Prerequisite knowledge

• None

Further thinking

We have seen that when there’s errors in the system, it can take a lot more qubits to encode information. How do you think this affects Shor’s algorithm?

Solution

Further reading

Check out Shor's algorithm and this implementation in photonic qubits where the number 15 is factorized!