Nature also calculates
When light strikes the green leaf, it induces all kinds of chemistry that produce oxygen at the end of the chemical reaction. And the process between input light and output oxygen can be viewed as a calculation. This changing of perspective is interesting because nature calculates a lot faster and smarter than our computer does. The key ingredient that nature uses is, in fact, quantum mechanics. In quantum mechanics, you can be 0 and 1 at the same time. Scientists started to use these principles in order to build a really powerful computer. It is called a quantum computer.
Quantum computing is the use of quantum-mechanical phenomena such as superposition and entanglement to perform computation. Quantum Computing was started in the early 1980s when Richard Feynman and Yuri Manin expressed the idea that a quantum computer had the potential to simulate things that a classical computer could not.
Qubits are fundamental to quantum computing and are somewhat analogous to bits in a classical computer. Qubits can be in a 1 or 0 quantum state. But they can also be in a superposition of the 1 and 0 states. However, when qubits are measured the result is always either a 0 or a 1; the probabilities of the two outcomes depends on the quantum state they were in.
If we want to make supercomputer 2 times faster we need to make it 2 times bigger. If there is a quantum computer with the same starting point, if we wont to make it 2 times faster we only have to add one qubit. This means that supercomputer computational power scales linearly while the computational power of quantum computers scales exponentially.
A single object can actually be at different locations at the same time. We call this superposition. A very simple example that shows superposition is a molecule of oxygen. Two oxygen atoms are held together by horizontal lines in the oxygen molecule. These horizontal lines share an electron, but these electron does not sit in the middle between these two atoms, it actually divides up and go to a superposition and occupies the space around these two oxygen atoms. These two parts of the electron do not wont to be so separated, so they keep to atoms of oxygen together. So that is actually superposition that binds atoms in molecules. Actually, our bodies consist of molecules so without a superposition, our body will fool apart.
So where we can apply them?
Here are three interesting applications of quantum computers:
Security – quantum uncertainty could be used to build private keys for encrypting messages sent from one location to another so that hackers could not secretly copy the key. These kinds of unbreakable encryption are already being tested by banks and other institutions worldwide.
Biology, health care, and medicine – describing and calculating all of the properties of all the atoms in the molecule is a computationally difficult task, even for a supercomputer. A quantum computer could do better because it operates using the same properties as a molecule it trying to simulate.
Machine learning – quantum computers could empower machine learning by enabling AI programs to search through gigantic datasets.
Quantum computers will not replace the classical computer, but they will be used for special classes of problems where they will be proven superior.