Computers have got faster over time, much faster, and it’s not just about the speed that an individual processor can perform calculations, they also have many more processors, all performing different calculations at the same time. Quantum computing is something different entirely, its not about performing arithmetic faster, its an entirely new way of computing with inherent uncertainty. This will not replace conventional computing for most applications but it will give huge advantages in certain specific cases.
In a digital computer, data is broken down into bits which can have a value of 0 or 1. In quantum computing data is represented by qubits. As calculations are being carried out, qubits can be in a superposition of both 0 and 1 at the same time, with some probability of being either a 0 or a 1. This is equivalent to Schrodinger’s cat being both dead and alive inside a sealed box, and not actually becoming only one of these states until someone looks inside the box. Just like Schrodinger’s cat, when the qubit is measured, it must represent either a 0 or a 1. A number of physical objects could be used as a qubit, such as a single electron, a photon or a nucleus. These quantum objects represent binary ones and zeros by their quantum spin state.
When a group of qubits are all in different states of superposition they are said to be fully entangled, allowing them to store almost unimaginable quantities of data. Three hundred qubits in a fully entangled state could theoretically simulate every particle in the universe! However, they can only be measured as binary ones and zeros. Therefore, quantum computers are only useful for algorithms that can make use of the complexity of quantum entanglement during the calculations and then arrive at a simpler state for the final result.
Quantum computing could be used to create unbreakable encryption keys, or to simulate molecules in drug development. Simulating all the quantum properties of all the atoms in a complex molecule is extremely challenging for conventional computers. The uncertainties inherent in the quantum effects must be simulated by repeating the calculations many times, in a process known as Monte Carlo simulation. Quantum computers could operate using actual quantum properties to directly simulate the properties of the molecule, without these cumbersome iterations.
Quantum entanglement could also allow quantum computers to transmit data instantaneously, over any distance, without requiring any wires or wireless transmission hardware.