Do you use online banking? Buy things on Amazon? Or
post stories on Facebook? If so, then Quantum Computing can have a major impact
on how you do things on the internet. To explain how, we must start with
understanding internet security.
Have you ever noticed that some websites, like
your banking site for example, start with https and show a little lock next to the
address bar, while others start with http and do not have the lock? The https
and the lock mean that it is a secure site and any information you enter on a
form is guaranteed to only be readable by the official owners of the site. This
works through a process of encryption using the secure sockets layer (ssl).
Current encryption techniques work off of a
precept that factoring numbers, especially extremely large prime numbers that
have been multiplied together, is an extremely hard problem for a computer to
solve. Modern encryption techniques multiply two 2048-bit prime numbers
together to establish an encryption scheme. The two prime numbers represent the
client and server and each one knows the other prime, but no one else listening
on the line knows either prime.
To factor such a large prime number will take a
nearly infinite time with current computer technology. Every digit must be
sampled independently, each taking two steps, and even with the most powerful
computers it would take more than the current age of the universe to factor the
primes. A good mathematician can factor them by hand in about a decade, by
which time your bank transaction information is useless.
This is where quantum computers come into play. A
quantum computer works off the concept of a qubit. A qubit can be thought of as
a coin flipping in the area, we do not know whether it is heads or tails until
we catch it and look. It has equal probability of being either one before it lands.
This state is known in the quantum computing world as superposition. Another
power of a qubit is called entanglement. Entanglement is where two qubits
exactly mirror each other; regardless of what happens, they are always in
either equal and opposite states or exactly the same state, depending on how
they became entangled.
These two properties of qubits allow a quantum
computer to know all the possible outcomes for any possible input
instantaneously. As a result, they can factor very large prime numbers very
quickly, in effect, breaking modern cryptography. This is bad news for your
bank account, but the good news is that this requires a large, fault-tolerant quantum
computer.
Today we have small, noisy, intermediate-scale
quantum (NISQ) computers. NISQ systems have relatively small qubit counts of
less than 50 qubits. The qubits in these systems are noisy and error prone,
creating problems with successful results in things like breaking encryption,
and they are too small. They can only factor up to 50-bit numbers.
Current predictions are that we are between 10-20
years away from having a fault-tolerant quantum computer, with 2048 qubits
capable of breaking modern encryption, and the banking industry is already
working on quantum encryption techniques in preparation for the future. So
there is no real need to worry for at least a decade.
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