Smartpedia | What is a quantum network?

Quantum networks are the foundation for future high-speed enterprise communications.

The technology required for a seamless quantum network must be deployed at multiple nodes over long distances to enable ultra-secure, reliable and fast qubit data transmission. The principles of quantum physics are the foundation of quantum networks.

What is a quantum network?

Quantum networking is directly related to quantum physics and communication. Its physical infrastructure consists of multiple quantum processors that exchange information in the form of qubits. Quantum networking is the process of transmitting and receiving information encoded in qubit states within a quantum network.

Quantum physics principles govern quantum network protocols and algorithms, which exchange information in a highly encrypted manner between multiple nodes distributed over long distances. These principles enable quantum network protocols to provide fast, reliable and secure communications.

Since quantum networking is a completely new networking technology, it may be a challenge for providers to commercialize it. This article discusses some of the advantages and disadvantages of quantum networking, as well as the challenges associated with its implementation.

Benefits of quantum networking

Although still in its infancy, quantum networks have the potential to provide a variety of next-generation advantages. Benefits of quantum networks include:

• Wide range of applications
• Solve problems together
• Long distance communication
• Reliable transmission
• Enhanced security
• Quantum cryptography
• Error detection and correction

Wide range of applications

In a quantum network, the network sends and receives information in the form of quantum bits (often called logical qubits). The entangled or superposition state of the qubits encodes the information. These qubits exist in multiple states at the same time, 0, 1, or both, but change when measured due to the collapse of the wave function.

Photon energy drives most quantum network technologies. The dual-particle and wave-like properties provide a variety of quantum-related applications such as quantum sensing, quantum teleportation, quantum simulation, etc.

Solve problems together

Ideally, a certain number of quantum networks can deploy multiple nodes to solve common problems. Quantum networks require high computing power and speed to calculate complex problems.

For example, distributed quantum computing is a quantum network cluster where multiple quantum processors are connected to jointly solve complex problems and perform high-speed calculations. The quantum network infrastructure can also be connected to the quantum internet, forming a quantum Internet of Things with quantum processors, sensors, repeaters, controllers and other devices.

Long distance communication

Quantum entanglement describes the long-distance transmission of quantum bits. In a quantum network, two or more quantum bits are in an entangled state with the same or opposite spins. These quantum bits are first intertwined and then separated by a large distance.

If the state of one qubit changes when measured, the other qubit automatically changes as well. Quantum entanglement is sometimes called quantum teleportation because the actual qubits are not transmitted through the channel to routers and other network devices.

Reliable transmission

The TCP/IP model describes the transmission of packets across a network and their acknowledgment by the receiver. Quantum networks eliminate the need for acknowledgments because the state of the interleaving can be predicted.

Quantum repeaters are deployed at single or multiple locations to enhance the reliability, computing power and range of quantum networks. In other words, quantum repeaters reduce the effects of decoherence and signal loss to provide accurate information.

Enhanced security

The no-cloning theorem states that it is impossible to copy quantum information from an unknown state to another state. A hacker, known as an eavesdropper, cannot create a completely independent and identical copy of an unknown entangled quantum state.

However, hackers can try to manipulate qubits in a quantum network to gain a certain degree of replication. Quantum network protocols can detect manipulation on the channel and provide quantum error detection and correction functions to ensure a high level of security.

Quantum cryptography

Quantum networks incorporate quantum cryptography to encrypt and decrypt information. Quantum key distribution (QKD) is a quantum encryption protocol that shares keys in the form of qubits or polarized photons over an unsecured network.

In quantum cryptography, Heisenberg's uncertainty principle states that it is impossible to measure both the speed and position of a particle simultaneously to achieve an ultra-secure connection. The sender and receiver compare the measurement results to eliminate errors, detect third-party attempts, and decrypt the key. QKD protocols include BB84, decoy-based QKD, etc.

Error detection and correction

Quantum networks can help achieve high precision through quantum error detection and correction algorithms. Many error correction algorithms detect deviations in the received qubit state from the transmitted photon.

These protocols enable users to identify possible hacking attempts on quantum networks. Some error-correcting codes include short-range codes, boson codes, and bit-flip codes.

Challenges of quantum networking

Despite the many benefits of quantum networking, it is not without its challenges. Disadvantages of quantum networking include:

• The fragility of quantum information
• Complex manipulation
• Slow communication
• Scalability issues
• High cost
• Complex integration

The fragility of quantum information

Quantum information is inherently fragile, which makes it susceptible to environmental factors such as quantum interference, decoherence, and signal loss. Network professionals can deploy quantum repeaters across multiple network segments to maintain the accuracy of quantum networks. In addition, quantum operators need to operate on qubits during the error correction process.

Complex controls

From an enterprise perspective, the inability to copy quantum states could limit many conventional applications. In these cases, quantum logic gates manipulate quantum information between nodes to achieve transmission. However, quantum logic gates cannot violate the no-cloning theorem.

Slow communication

A common misconception is that quantum communication is faster than the speed of light. However, quantum networks often use traditional communication methods to eliminate the possibility of superluminal communication. Quantum networks use optical fibers for communication, just like the traditional internet.

Scalability issues

Long-distance quantum communication is currently hypothetical, because quantum networks with many nodes use short distances to separate them. Quantum networks typically have fewer processors than classical networks. Quantum processors can actually generate fewer superposition or entangled qubits in quantum network protocols.

High cost

The implementation and maintenance of quantum networks require high-cost investments. Quantum network hardware and software require significant investments in technology, engineering, and cost. High-budget industries, such as government, deep space research, and cryptography projects, are better suited for quantum networks.

Complex integration

Quantum networks have their own standardization and interoperability required for hybrid networks. In order to merge with the classical Internet, the network must deploy a large number of quantum processors. In addition, the TCP/IP communication model and quantum networks work on different technologies, making it difficult to combine them.

The future of quantum networks

Large businesses and organizations are interested in quantum networks to enable optimized computing and fast communications and solve complex problems.

It will take years for quantum networks to be commercially operational at an affordable price like current computer networks. In the next few decades, multiple industries such as IT, space, research, healthcare and retail can achieve fast communication and high-performance computing through quantum networks.