Key terminology
Quantum technology
This primer provides an introduction to quantum computing, a branch of quantum technology and outlines its key concepts at a high level.
Quantum computer
Quantum computing uses the unique properties of quantum particles to perform calculations in ways that can be faster and more powerful than classical computers, enabling it to solve certain problems that would otherwise be impractical or impossible.
Qubit (quantum bit)
A qubit is the basic unit of information in a quantum computer, similar to a bit in a classical computer. Unlike a classical bit, which can only be either 0 or 1, a qubit can exist in a combination of both states at the same time. This allows quantum computers to process and explore many possibilities simultaneously.
Superposition
Superposition is the ability of a qubit to exist in multiple states at once. While a classical bit is always either 0 or 1, a qubit can represent a combination of both until it is measured. This is one of the key features that gives quantum computing its potential power.
Entanglement
Entanglement is a part of quantum that links two or more qubits so that they become connected, even when separated by large distances. A change to one qubit can affect the others, allowing quantum computers to perform complex calculations far more efficiently than classical computers.
Quantum Supremacy
Quantum supremacy is used to describe a quantum computer outperforming a classical computer on a specific task.
Quantum Advantage
Quantum advantage is used to describe a quantum computer performing a useful or meaningful task better (in terms of price, time-to-solution, accuracy, or scale) than the best-known classical computing approach.
Classical Computer
A classical computer is the type of computer we use today. It processes information using bits, which can only be in one of two states: 0 or 1. Quantum computers, by contrast, use qubits, which can represent multiple possibilities at the same time.
Quantum Computers: Advantages and Disadvantages
Advantages:
- The ability to carry out a computational task more efficiently than a classical computer. For certain problems, classical computers are unable to give a useful answer in a realistic time scale because the number of possibilities to assess are too great. However, quantum computers can represent multiple states at once and therefore provide answers in a realistic and useful timeframe in response to those questions.
- The ability to solve certain ‘hard’ problems that are beyond the capability of a classical computer.
Disadvantages:
- Ensuring qubits stay in stable state.
- Transferring information in and out for the computer.
- Quantum computers are vulnerable to errors given the components are so sensitive and thus, qubits can lose their quantum state. As a result, quantum computers can store or manipulate information incorrectly.
- Errors accumulate over time, preventing them from executing algorithms.
Will Quantum Computers replace Classical Computers?
There are limits on the growth possible with classical computers. Moore’s Law states that the number of transistors that can fit on a silicon chip doubles every two years. There are, therefore, limits on the exponential improvement possible with classical computers.
However, Quantum computers cannot replace classical computers - they are not being designed to have that effect. Classical computers are relatively robust machines that execute tasks well. Quantum computers require sophisticated high-speed infrastructure and often need cryogenic temperatures to operate. Quantum computers are typically deployed in data centres “as-a-Service” and surrounded by state-of-the-art High Perform Compute. Quantum computers will most likely require classical computers to support their specialized abilities and so classical computers, even in the dominion of the quantum computer will remain important and relevant. The interplay of quantum computing and classical computing is often referred to as hybrid approaches.
