## Introduction to Entanglement

Author: Jayakumar Tatipathi

## Entanglement

When two atoms are entangled, the state of one particle changes rapidly at a great distance in such a manner that it changes the state of the other particle. The relationship between these states is strongly correlated and does not change despite their separation. It is hard to believe, but playing a note in one part of the room results in hearing it echoed perfectly in other rooms several miles away. Itâ€™s akin to quantum entanglement.

** Entanglement** is a fundamental concept of quantum mechanics that describes a non-classical correlation, or shared quantum state, between two or more quantum systems (or quantum particles) even if they are separated by a large distance. This phenomenon is also known as quantum non-locality. Quantum systems are described by a mathematical object called a wavefunction, which contains information about the possible outcomes of measurements that can be performed on the systems. When two or more quantum systems are entangled, their wavefunction cannot be expressed as a product of individual wavefunctions for each system. Instead, the systems are described by a single wavefunction that captures the correlation between them. The fact that entangled systems are described by a single wavefunction means that any actions or measurements made on one of the systems affect the state of the other systems.

**Advantages****a.** In quantum computing, entanglement is used to enable quantum parallelism. Quantum computer, leveraging the Entanglement, manipulates many qubits in a single operation, instead of manipulating each qubit individually, which is the case in classical computing.**b.** Quantum computers implement various protocols and algorithms.**c.** Entanglement is also a key resource for quantum error correction, which is necessary to protect quantum information from decoherence and other errors. By creating and manipulating entangled states, quantum computers can detect and correct errors in a way that is not possible for classical computers.

**Application of Quantum Entanglement:****a**. Quantum Computing: The central notion behind quantum computing is the concept of entanglement, which is a phenomenon that does not occur with classical bits. Classical bits are either 0 or 1. But, unlike classical bits, qubits are capable of assuming both states of 0 and 1 concurrently; hence, superposition makes this possible. As a result of this property called entanglement in qubit computing, it has been found that they have an exponential performance advantage over conventional computer systems when carrying out complicated calculations. Such revolutionary breakthroughs may be seen in sectors like material sciences, among other areas, if harnessed properly, including cryptography.

**b.** Quantum Cryptography: The top priority when it comes to data security is now in high demand in a world where information is easily accessible and prone to cyberattacks, among other dangers. Quantum entanglement offers a highly reliable method for ensuring entangled encryption keys that cannot be cracked theoretically through quantum key distribution (QKD). During eavesdropping the key, since any slight intrusion will disrupt the entanglement, the communicating parties will realise any effort to snoop.

**c.** Teleportation: It means transferring one particleâ€™s state into another particleâ€™s without moving the particles physically from their initial place to another. So, scientists are investigating this theory to be able to create the most secure lines ofÂ communication.