New research claims breakthrough in scaling quantum communications technology

While quantum computing promises to offer major breakthroughs in terms of the applications that it can power, one of the biggest challenges that exist today lie in scaling the technology for real-world, industrial usage. It is this that a new research project, published by a team from Canada’s Simon Fraser University in Nature journal earlier this month, has claimed to have made progress on – and the end results could potentially impact the field of quantum communications technology.

The researchers found that in silicon, a “luminescent defect”, or a missing photon from the silicon in question, can help create a “photonic link”. This link can help qubits, the fundamental particle of quantum computing, to be transferred from one point to another at scale. Therefore, it could be a solution to enabling transfers of qubits in large quantities and over large distances – something that is an industrial challenge today since the existence of qubits in the quantum state is not stable over large distances.

The qubit, the fundamental particle of quantum computing, is the equivalent of a bit in classical computing – or computing as we know it today. Bits can exist in only one state at one time, which means that the information being transferred using the principles of today’s classical computing can be in one particular form at any given time. Think of this as the state of a switch – which can either be on or off, and not both at the same moment.

A qubit, on the other hand, can be both on and off – hence offering massive potential for new applications that can transform high performance computing, global communications, information security and other areas in unprecedented ways.

However, one of the biggest challenges lies in transferring qubits from one point to another. Research projects state that the range of distance over which qubits can be transferred is in hundreds of kilometres today, due to the fundamental properties of quantum physics.

One of the key factors for this lies in quantum entanglement, which states that when two qubits interact, their properties get ‘entangled’. Once this relation is established, any changes to one qubit will reflect in the same way in the second qubit that is linked to the first. Researchers have stated that this could be of massive significance in areas such as cyber security.

For instance, if the cryptographic key of a message between a sender and receiver is encoded into qubits, any party attempting to interfere this message (something similar to what we refer to as a ‘hack’ today) would cause the quantum state of the key to be dissolved. However, the interceptor would not be able to decrypt the message, since the key resides in the value that the qubit carries. This value would only be revealed to the targeted sender, thereby making the qubit key impossible to crack.

However, such transmission of data has not been possible until today, since the state of quantum entanglement of qubits, as well as the quantum state in which qubits exist, cannot be sustained over long distances.

It is this that the latest research claims to solve. According to the researchers, the first advantage is the widespread usage of silicon in today’s communication, network and technology infrastructure, which would allow this technology to be scaled. Furthermore, Stephanie Simmons, Canada Research Chair in Silicon Quantum Technologies, said in a statement that the ‘T centers’, which is the luminescent defect in silicon mentioned above, emit light at the same wavelength that is used by modern optic fibers for long distance data transfers and communications.

“When your silicon qubit can communicate by emitting photons (light) in the same band used in data centres and fiber networks, you get these same benefits for connecting the millions of qubits needed for quantum computing,” Simmons said.

In other words, this link based on the silicon ‘T centers’ would allow qubits to retain their quantum properties over long distances, and allow quantum communications technologies to scale. At the heart of this breakthrough is the ability to use existing communications infrastructure for quantum purposes, which they have reportedly succeeded in achieving.

The researchers also stated that such a breakthrough could mean that more applications could use a combination of existing high performance computing infrastructure, as well as quantum computing, to achieve unprecedented use cases and standards in telecommunications and information security, among other fields.