What, exactly, is a quantum computer? The word ‘quantum’ is often associated with stuff that’s small – atoms, quarks, photons. So you might think that a quantum computer is just a really, really small computer. And, in a sense, you’d be right.
Current computer technology is based on silicon chips. Messages are relayed through the computer via electrical currents, and data is stored in ‘binary’ code – basically through a series of ‘0’s and ‘1’s. For example, the number 42 in binary is 101010. Each number and letter has a different binary code, and the computer can save data in binary form and then read it back later, putting it back into the form you see on your screen.
The data is stored as binary in a magnetic material. All disks – hard drives, USB drives, you name it – are magnetic, and store the data as the magnetic field of each of the material’s particles. Each atom in the disk has a magnetic field pointing either ‘up’ or ‘down’ (corresponding to a ‘1’ or a ‘0’) and when the computer reads the data, it passes a sensor over the material and reads either a ‘1’ or a ‘0’.
(CDs work in a different way – they have very small notches pressed into them to create a ‘1’. When the sensor – this time, a laser – passes over the CD, either a notch – a ‘1’ – or the normal CD depth – a ‘0’ – is recorded, and the CD player can read the data back.)
Quantum computers would work in much the same way – but instead of ‘flipping’ the magnetic field of particles in a disk, a property of quantum particles called ‘entanglement’ is used. This allows the quantum state of each ‘qubit’ (particle) to be changed, therefore allowing data to be changed and stored. There are different types of qubits – photons (particles of light), atoms, and ions (atoms which have no electrons).
In the way they work, there isn’t really much of a difference between quantum computers and the computers we currently use. The main advantage is due to quantum parallelism, which allows a quantum computer to perform multiple state-flips at the same time. This means that the quantum computer would be able to work a lot faster than the ones we have today – no more waiting for YouTube videos to stream!
There is one downside to this exciting new technology, though – as things currently stand, data encryption would not be able to stop a quantum computer from hacking into bank accounts, PayPal, Amazon… you name it. The current system can be hacked but the advantage it has is that it would take a computer ages to do it. Quantum computers, however, would be able to hack the encryption in no time.
So while there are scientists working on getting quantum computers up and running, there are also scientists working on creating a new way to encrypt data before they get there!