Quantum Communication: Unlocking the Possibilities of the Quantum Network

Saturday - October 14 2023, 19:29 UTC - 1 year ago

This technology for storing and transmitting quantum information over lossy links could provide the foundation for scalable quantum networking. By connecting quantum sensors, interconnecting chips, and using quantum satellites in a global quantum internet, agencies can harness the computational power of quantum computing plus applications in defense, healthcare, artificial intelligence and cybersecurity. However, traditional communication systems that measure and copy bits could destroy qubits upon measurement.

This technology for storing and transmitting quantum information over lossy links could provide the foundation for scalable quantum networking. The popular children’s game of telephone is based on a simple premise: The starting player whispers a message into the ear of the next player. That second player then passes along the message to the third person and so on until the message reaches the final recipient, who relays it to the group aloud .

Often, what the first person said and the last person heard are laughably different; the information gets garbled along the chain. Such transmission errors from start to end point are also common in the quantum world. As quantum information bits, or qubits (the analogs of classical bits in traditional digital electronics), make their way over a channel, their quantum states can degrade or be lost entirely .

Such decoherence is especially common over longer and longer distances because qubits — whether existing as particles of light (photons), electrons, atoms, or other forms — are inherently fragile, governed by the laws of quantum physics, or the physics of very small objects. At this tiny scale (nanoscale), even slight interactions with their environment can cause qubits to lose their quantum properties and alter the information they store .

Like the game of telephone, the original and received messages may not be the same."One of the big challenges in quantum networking is how to effectively move these delicate quantum states between multiple quantum systems," says Scott Hamilton, leader of MIT Lincoln Laboratory’s Optical and Quantum Communications Technology Group, part of the Communications Systems R&D area. "That’s a question we’re actively exploring in our group .

"As Hamilton explains, today’s quantum computing chips contain on the order of 100 qubits. But thousands, if not billions, of qubits are required to make a fully functioning quantum computer, which promises to unlock unprecedented computational power for applications ranging from artificial intelligence and cybersecurity to health care and manufacturing. Interconnecting the chips to make one big computer may provide a viable path forward .

On the sensing front, connecting quantum sensors to share quantum information may enable new capabilities and performance gains beyond those of an individual sensor. For example, a shared quantum reference between multiple sensors could be used to more precisely locate radio-frequency emission sources. Space and defense agencies are also interested in interconnecting quantum sensors separated by long ranges for satellite-based position, navigation, and timing systems or atomic clock networks between satellites .

For communications, quantum satellites could be used as part of a quantum network architecture connecting local ground-based stations, creating a truly global quantum internet.However, quantum systems can’t be interconnected with existing technology. The communication systems used today to transmit information across a network and connect devices rely on detectors that measure bits and amplifiers that copy bits .

These technologies do not work in a qubit world — they destroy qubits upon measurement.