# Understanding Quantum Computing

## The basics of quantum computing

Quantum computing primer

#### What are classical computers?

The computers we use today are known as classical computers.

### What are classical computers?

The computers we use today are known as classical computers. They’ve been a driving force in the world for decades -- advancing everything from healthcare to how we shop. But there are certain problems that classical computers will simply never be able to solve. Consider the caffeine molecule in a cup of coffee. Surprisingly, it’s complex enough that no computer that exists or could be built would be capable of modeling caffeine and fully understanding its detailed structure and properties.

#### What is quantum computing?

A quantum computer is an entirely new type of system based on the properties of quantum physics.

### What is quantum computing?

Nature -- including molecules like caffeine -- follows the laws of quantum mechanics, a branch of physics that explores how the physical world works at the most fundamental levels. At this level, particles behave in strange ways, taking on more than one state at the same time, and interacting with other particles that are very far away. Quantum computing harnesses these quantum phenomena to process information in a novel and promising way.

#### How do quantum computers work?

Quantum computers can explore an exponential number of possibilities.

### How do quantum computers work?

Classical computers encode information in bits. Each bit can take the value of 1 or 0. These 1s and 0s act as on/off switches that ultimately drive computer functions. Quantum computers, on the other hand, are based on qubits, which operate according to two key principles of quantum physics: superposition and entanglement. Superposition means that each qubit can represent both a 1 and a 0 at the same time. Entanglement means that qubits in a superposition can be correlated with each other; that is, the state of one (whether it is a 1 or a 0) can depend on the state of another. Using these two principles, qubits can act as more sophisticated switches, enabling quantum computers to function in ways that allow them to solve difficult problems that are intractable using today’s computers.

#### What can quantum computers do?

Quantum computing has the potential to solve complex problems ranging from drug discovery to machine learning.

### What can quantum computers do?

Quantum systems may untangle the complexity of molecular and chemical interactions leading to the discovery of new medicines and materials. They may enable ultra-efficient logistics and supply chains, such as optimizing fleet operations for deliveries during the holiday season. They may help us find new ways to model financial data and isolate key global risk factors to make better investments. And they may make facets of artificial intelligence such as machine learning much more powerful when data sets are very large, such as in searching images or video.

## What does a quantum computer look like?

A quantum computer looks nothing like the system you have on your desk or in your pocket, though those devices can be used to access a quantum computer via IBM Cloud. IBM's quantum computer places quantum chips inside a refrigerator that is very cold -- colder than outer space -- in order to keep qubits in the proper state to perform calculations. Heat, noise or electromagnetic waves can interfere with this. A quantum computer is major feat of engineering.

Look inside a quantum computer

Continue exploring the possibilities of quantum computing with IBM.

Quantum computing on IBM Cloud

Access the IBM Quantum Experience, a virtual lab where you can design and run your own quantum algorithms through the IBM Cloud on a five-qubit quantum processor.

Types of quantum computing

Learn about the three known types of quantum computing.

Why IBM is building a universal quantum computer

Quantum Potential

Quantum computers will tackle currently unsolvable problems in Chemistry and other areas.