The Quantum Internet

 Quantum Internet: at the Verge of an Emerging Technology

- Overview

A quantum internet is a future network that transmits data using qubits and entanglement instead of classical bits, enabling ultra-secure communication and new quantum applications. 

Unlike the classical internet, it uses quantum phenomena to create connections and allows for the detection of eavesdropping, promising unprecedented levels of security and new functionalities beyond secure data transfer.

How it works:

• Qubits instead of bits: Instead of 0s or 1s, data is represented by qubits, which can exist in multiple states simultaneously (superposition).
• Entanglement: Pairs of entangled particles remain connected, no matter the distance, so that the state of one instantly influences the state of the other. This allows for quantum networks to establish connections without directly passing data through the entire network.
• Entanglement distribution: Quantum networks focus on distributing entanglement between nodes, allowing for secure connections and tasks like teleportation.

2. Key Characteristics:

• Enhanced Security: The fundamental properties of quantum mechanics allow for the detection of any attempt to intercept or measure the qubits during transmission.
• New Functionalities: Beyond security, quantum networks enable applications like distributed quantum computing, enhanced sensing, and secure quantum key distribution.
• Still Hypothetical: While there has been significant progress in building the necessary components and demonstrating entanglement, a fully functional quantum internet is still in development and not yet a widespread reality.

- The Vision of the Quantum Internet

The quantum internet is a network of quantum computers designed to send, receive, and process information encoded in quantum states (qubits), not to replace the classical internet, but to enhance it with capabilities like secure quantum cloud computing and distributed quantum computing for solving complex problems. 

This network will leverage quantum communication, using devices like quantum repeaters to overcome the challenges of sending fragile qubits over long distances. 

Potential applications include unbreakable quantum cryptography and the ability for multiple quantum computers to work together on tasks beyond the reach of even the most powerful classical computers. 

1. What it is:

• A network of interconnected quantum computers and devices that use quantum mechanics to transmit information.
• Information is encoded in qubits, which are the quantum equivalent of bits in classical computing.

2. What it is not:

• A replacement for the current internet.
• For everyday consumer use in the near future.

3. How it works:

• Qubits (quantum data) are sent across the network.
• Sending qubits over long distances is challenging because they are easily lost and cannot be copied, so quantum repeaters are used to extend the range of quantum communication.
• It will allow for capabilities like quantum teleportation (transferring quantum states) over distances.

4. Key Applications and Features:

• Quantum Cryptography:Enables ultra-secure encryption protocols, making communications virtually unhackable.
• Distributed Quantum Computing:Allows multiple, potentially smaller quantum computers to work together, simulating a single, large-scale quantum computer to solve complex problems.
• Quantum Cloud Computing:Provides a way to access quantum computing resources over the network for tasks that require significant computing power.

5. Challenges and Future:

• Long-Distance Transmission:The fragility of qubits makes them difficult to send over long distances, requiring advanced techniques like entanglement swapping and quantum memory.
• Deployment Stages:The development is seen as a staged process, beginning with networks that can establish quantum communication between any two points on Earth.
• Timeline:Interstate quantum networks are anticipated within 10 to 15 years, with consumer-viable quantum computers possibly emerging in the late 2030s or early 2040s

- The Potential Applications of The Quantum Internet

The quantum Internet is a theoretical network of quantum computers that will use quantum technology to send, receive, and compute information. It will work by encoding signals with individual particles of light, rather than classical bits, to send information at ultra-fast speeds. 

The quantum Internet is intended to coexist with the Internet we use today, and be used to solve specific problems. It has the potential to revolutionize how we communicate, compute, and secure data. 

Some of the potential applications include:

• Secure communication: The laws of physics would guarantee privacy.
• Networked quantum computing: Quantum processors could be connected to create a large quantum computing cluster.
• Remote quantum computing: Users and providers could perform secure quantum computing in the cloud. 

The development of quantum technologies is resource intensive and will require significant investment. It will also require the integration of new quantum devices with existing networks. 

- The Aim of the Quantum Internet

Today’s Internet is a playground for hackers. From insecure communication links to inadequately guarded data in the cloud, vulnerabilities are everywhere. 

The main advantages of a quantum communication network over a conventional one are speed and security. Entanglement makes it possible to communicate instantly across arbitrarily large distances in principle. No matter how far apart you put two entangled qubits, acting on one will have an instant and measurable impact on the other.

The Quantum Internet is a communication network with quantum nodes and quantum links that allows to the parties to perform efficient quantum communications. 

The aim of the quantum Internet and quantum repeater networks is to distribute quantum entanglement between distant nodes through a chain of intermediate quantum repeater nodes. 

In the quantum Internet, the quantum nodes share entangled connections that formulate entangled links. 

- The Quantum Internet Technology

The quantum Internet could revolutionize how computers talk to each other. Parts of the quantum Internet will be realized by sending quantum light through waveguides, such as optical fibres, that are connected to quantum devices. The ultimate vision of the quantum Internet is a connection of potentially billions of quantum devices within the same network. But it's hard to model such complex networks theoretically, and existing models can only cope with very simple networks.

The Quantum Internet technology is something that today only really exists on paper and on the drawing boards of scientists. Yet, it is now a great moment to start discussing its potential, as a lot of research effort is being made towards the realization of such a quantum Internet. 

Although a fully realized quantum network is still a far-off vision, recent breakthroughs in transmitting, storing and manipulating quantum information have convinced some quantum physicists that a simple proof-of-principle is imminent.

- Quantum Teleportation

With advances in quantum computing, many experts in the quantum industry are concerned about when the quantum internet (a network in which quantum computers and quantum technologies communicate with each other) will emerge. A quantum internet could send signals not only faster, but more securely. 

According to a 2021 paper in the journal Nature: "The quantum internet will be based on a protocol called quantum teleportation, which will transmit quantum information from one node to another over long distances. Teleportation Not only will it help extend quantum communication distances, but it will also be crucial for distributed quantum computing."

It's difficult to predict when next-generation infrastructure will be functional (as it's likely to be launched over shorter distances), but researchers are working on various devices and methods to bring this network closer to reality.

- Quantum Entanglement

In quantum entanglement, particles interacting at a certain point retain a connection and can become entangled with each other in pairs, a process called correlation. Knowing the spin state of an entangled particle -- up or down -- can tell one that its partner's spin is in the opposite direction. 

Quantum entanglement allows qubits separated by incredible distances to interact instantaneously (not limited to the speed of light). Regardless of the distance between related particles, as long as they are isolated, they remain entangled.

[Venus - NASA]

- Quantum Teleportation

Quantum teleportation is a technique for transmitting quantum information from a sender in one location to a receiver some distance away. While teleportation is described in science fiction as a means of transferring physical objects from one location to another, quantum teleportation only transmits quantum information. 

A team of scientists and researchers has achieved, for the first time, sustained, high-fidelity "quantum teleportation" -- the instant transmission of "qubits" (qubits), the basic units of quantum information. A collaborative team, including NASA's Jet Propulsion Laboratory, has successfully demonstrated sustained long-distance teleportation of photonic qubits (light quanta) with over 90 percent fidelity. The qubits are teleported 44 kilometers (27 miles) over a fiber-optic network using state-of-the-art single-photon detectors and off-the-shelf equipment.

- Quantum Teleportation: Paving the Way for a Quantum Internet

In July, 2020, the U.S. Department of Energy unveiled a blueprint for the first quantum internet, linking its multiple national laboratories across the country. A quantum internet will be able to transmit massive amounts of data over great distances at speeds exceeding the speed of light. You can imagine all the applications that could benefit from this kind of speed.

A consensus is emerging around the world that systems that communicate using quantum mechanics represent one of the most important technological frontiers of the 21st century. Scientists now believe that construction of a prototype will be possible within the next decade.

- Quantum Internet: Hybrid Quantum Information Network

Quantum information networks are emerging as a disruptive technology, providing entirely new capabilities for information processing and communication, which will have a huge impact on the most secure internet connections and access in the future.

The researchers published their results, realizing a fundamental hybrid quantum network link. They demonstrated photonic quantum communication between two distinct quantum nodes placed in different laboratories, using a single photon as an information carrier. The researchers demonstrated the network using a telecommunications wavelength of 1552 nm.

The ability to transmit qubits via single photons between them is an important step in the development of hybrid quantum networks. Note that the classic information network, the World Wide Web, uses bits to keep information flowing across the network, processed and modulated by electronic circuits and chips, and transmitted by pulses of light to move information across the network.

A quantum information network, or quantum internet, processes and stores quantum information through quantum bits, or "qubits," in a quantum network. Therefore, there is the potential advantage of completely secure data transmission, which is one of the most important features required for internet connectivity and access.