Quantum Computing Basics

First, to begin with the concept and usage of quantum computers, we must go over the basics.

What is it?

Quantum computing uses specialized technology—including computer hardware and algorithms that take advantage of quantum mechanics—to solve complex problems that classical computers or supercomputers can’t solve, or can’t solve quickly enough. -IBM

Qubits

A normal computer functions over the concept of binary. A bit is like a switch in which it can have an off state(0) or an on state(1). Unlike normal computers, quantum computers get interesting when they provide the ability to not only be in a off or on state, but also be both simultaneously, known as the superposition. These special bits of the quantum computer-with the ability to be in the superposition-are called qubits, and they are able to process multiple possibilities simultaneously as the basic unit of information in quantum computing.¹

Entanglement

With qubits, there is also entanglement. In short, entanglement is when two or more particles have a connection between themselves where they share a quantum state.² Since some information is stored in superposition, entanglement allows some problems to be solved exponentially faster.

Overall

In fundamental contrast to classical computing, quantum computers use quantum circuits, gates, and algorithms to manipulate and use qubits. The most common example algorithms are Shor's algorithm³ and Grover's algorithm⁴. Both algorithms achieve their purpose faster than any classical algorithm can.

Real world applications

If a supercomputer gets stumped, that's probably because the big classical machine was asked to solve a problem with a high degree of complexity. - IBM

An example of this would be the modeling of advanced, specific, or large quantity models, such as modeling the movement of electrons or DNA sequences.

In the real word, even in the quantum computer's infancy, this technology is used in finance, pharmaceuticals, artificial intelligence, and in many more applications today.

Drawbacks

Quantum Computers face some challenges however. They need a perfect environment to operate, and interactions in the environment in which the computers are in can cause problems. First, the hardware needs to be very cold. To expand, the quantum processors need to be just above absolute zero in temperature.

Failure to have a perfect environment can cause decoherence - the occurrence of qubits losing their quantum state. This is another way of saying the qubits are not in superposition anymore, and are nothing more than classical computer bits.

This can affect scalability where it is challenging to maintain high coherence while scaling the number of qubits and quantum computers.

Fortunately, there are techniques such as error correction codes or quantum error correction(QEC) which aims to detect and correct the effects of decoherence before they can affect the computation at hand.

1. It is important to note that qubits are not useful by themselves,but have the ability to achieve the state of superposition, which is what makes them useful. ↩

2. The effects of entanglement can be seen even when the particles are distance, even by a great amount, to each other ↩

3. Quantum algorithm for integer factorization. When given an integer,N , this algorithm will be able to find all of N's prime factors. ↩

4. Quantum algorithm for searching an unstructured database or unordered list.  ↩