# What is Quantum Computing?

At very small scales, physical matter exhibits both particle and wave properties. Quantum computing leverages these phenomena, specifically quantum superposition and entanglement, to perform operations much faster than classical computers.

Industrial chemists, global shipping companies, engineering firms, and other organizations are using quantum methods to solve complex problems like molecular simulation. Learn how to get involved with the quantum revolution.

## What is Quantum Computing?

A quantum computer uses the principles of quantum mechanics to process data in new ways. It can perform certain calculations much faster than a conventional (or “classical”) computer, even ones that are currently thought to be impossible for any computer to solve.

A conventional computer uses bits, which are represented as either a 0 or a 1. Quantum computing takes advantage of the fact that at very small scales physical matter can exist in a mixed state (called superposition), with values that are probabilistic rather than definite, like the results of a coin flip.

Experts believe quantum computers could speed up the modeling of complex molecules, for example, leading to the development of new drugs. They may also help crack encryption methods that use a fixed number of digits, by performing calculations at an exponentially faster rate.

## What is Qubit?

A qubit is a quantum bit that holds information according to the mysterious laws of quantum mechanics. In contrast to the binary bits that comprise classical computers, quantum bits can store multiple combinations of zero and ones at once.

This allows them to perform calculations that would be impossible for classical computers to finish. As such, they are able to solve complex problems much faster than conventional machines can.

Despite their power, qubits are extremely fragile. The slightest vibration or change in temperature can cause them to lose their quantum state. To avoid this, qubits are kept in supercooled refrigerators or vacuum chambers. The research community is exploring a variety of materials that can act as qubits, including nanosized crystals and defects in diamond.

## What is Superposition?

A superposition is the state that a physical system can be in. A wave is a perfect example of a superposition. When two waves overlap, they either add together or cancel each other out, creating a pattern of undulations. When strummed on a guitar, the harmony of the chords is an example of teamwork between the individual wave patterns. Similarly, when throwing pebbles in a pond, different waves overlap and combine to make the ripple pattern.

The fundamental law of quantum mechanics states that a physical system can be in a variety of possible states, known as configurations. These are combinations of particles or fields, and each configuration has a unique probability distribution. This is similar to the concept of heads or tails when flipping a coin.

## What is Entanglement?

In physics, entanglement is the phenomenon whereby aspects of one quantum particle are dependent on the state of its partner, no matter how far apart they are. Einstein referred to this as “spooky action at a distance.”

The entanglement can be used to send information to Bob, but only if both Alice and Bob have the same classical information about the committed bit (e.g., the probability that a spin of one of the ancilla particles will be 0 or 1). The information can thus not be transmitted faster than light.

Physicists can create entangled particles in the laboratory by cooling and mixing pairs of particles, or by using subatomic processes such as nuclear decay. Entangled particles may be photons or other quantum particles such as electrons, quarks and gluons.

## What is Quantum Cryptography?

Quantum cryptography is a field of cryptographic techniques that apply quantum mechanics principles to data encryption and transmission so that hackers can’t access the information. It includes a number of cryptographic protocols and applications, including quantum key distribution (QKD) and actual encryption.

A fundamental aspect of quantum cryptography is that it makes eavesdropping impossible, since any attempt to intercept entangled photons would disturb the system, creating a detectable change that could alert the sender and receiver. This is because the laws of physics dictate that the state of a quantum system cannot be modified without disturbing it.

The development of quantum-safe cryptography is essential to ensuring that cybersecurity, communication and digital identity systems are protected against attacks using quantum computers. This will involve the migration to new PKI certificates that are designed to be quantum-safe.