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Chip-Based QKD System Will Live Up to Its Promise…. Someday

Rahil Patel   |   June 21, 2023

I recently had discussions with a few clients on their interest in new research in Quantum Key Distribution (QKD) technologies with novel claims that a photonic and electronic integrated circuit transmits secure keys at unprecedented speeds—this might just be practically too optimistic today.

The new quantum key distribution (QKD) system developed on integrated photonics is based on proof-of-principle experiments. The researchers claim that the new system integrates all components into chips except the laser and detectors. Thus, is has the potential to offer advantages like compactness, low cost, and ease of mass production. To understand these claims, we need to compare them closely with the existing system.

The existing QKD systems use the principles of quantum physics to create and distribute secure keys. A series of photons transmit key material from one point to another over a fibre cable. The photons, randomly generated, are in a quantum state, thus any attempt to read the photon information (eavesdropping) causes its state to collapse indicating a breach. QKD systems use a transmitter to send the encoded photons and a receiver to detect them.

In the new system, it is proposed that an external laser with a photonic and electronic integrated circuit produces and encodes photons at a speed of up to 2.5 GHz. The ensemble acts as a transmitter. A low-loss and polarisation-independent photonic integrated circuit and a set of external detectors that allows passive and simple detection of the transmitted photons act as a receiver. The two components connected with a standard single-mode fibre enable high-speed production of secret keys.

It is important to note that the new system also uses fibre to transmit keys from one end to the other. In terms of the rate of production of secret keys and quantum bit error rates, the new experiments produced results that are similar to those performed using conventional fibre-based components. If these two parameters remain the same, I see little value in the claims of unprecedented speeds.

Any business or government planning to store data for decades needs to evaluate the risks of this technology because the encryption could be compromised later. Robust defences on historical data take many years, so it would be better to apply these now. A big push to develop post-quantum cryptography is warranted.

On the contrary, Armos-QKD developed by QNu Labs, is a patented technology implemented successfully to enhance the security of existing systems. The technology does not compromise speed and comes in a set-top box-like device that is easy to implement and manage. It can be deployed on any network with minimal adjustments in a complete overlay architecture.

Integrated chips have become a household phenomenon. Therefore, visualising every technology in a semiconductor chip is understandable. However, unless there is concrete evidence of superior performance, ease of deployment, and significant cost efficiency, the innovation may not carry commercial viability. I am hopeful about advancements in QKD systems, but probably on different parameters that are comprehensive in production and practical in usage.

I acknowledge the benefits of integrated photonics provided it lives up to the expectations of complete integration of all components on the chip, scalable implementation, and ease of use. The impetus of adoption of this technology hinges on lucrative economics and industry relevance.

In the world of technology everything (eventually) shrinks in size and cost as its adoption scales. I am sure future innovations will continue to push the paradigm in QKD technology as well. Until then, QNu has a commercially viable technology available today that can be readily leveraged by the clients world over!

To know more about Armos, request a demo.

Author :

Rahil Patel
Chief Growth Officer, QNu Labs

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