India demonstrates its first 5 km free-space quantum key distribution link

[EdgeRatedR20]

QNu Labs, BISAG-N and IIT Gandhinagar have demonstrated India's first free space quantum key distribution link over a distance of about 5 km, The Quantum Insider reports. The link ran for 5.56 km between BISAG-N and IIT Gandhinagar on 27 and 28 September. Free space means the quantum signals travelled through open air rather than through fibre. That is the same basic approach needed for quantum links to satellites

The numbers are modest but solid. The secure key rate was 230 to 260 bits per second, the quantum bit error rate stayed below 5 percent and the link produced about one fresh 256 bit key every second. It used QNu Labs' pointing, acquisition and tracking system at a wavelength of 1550 nm. A test message was encrypted, sent and decrypted through a standard ETSI interface to show the system working end to end

Interestingly, the demonstration combined QKD with post quantum cryptography and quantum random number generation, rather than relying on QKD alone. That reflects the view of many security experts that QKD works best as one layer among several. QNu Labs chief executive Sunil Gupta said: "Quantum security will become meaningful at scale only when technologies operate across real communication infrastructure."

The partners see this as groundwork for longer distance quantum secure networks and eventually satellite quantum communication. China has led the world in this area for years with its Micius satellite, and India appears keen to build its own capability. As we discussed recently, agencies like the NSA remain sceptical of QKD for most uses, so it will be interesting to see where India takes this

Is free space QKD a practical technology or mainly a research showcase? And should countries invest in QKD at all, given the scepticism from the NSA and NCSC?

QNu Labs, BISAG-N and IIT Gandhinagar Demonstrate 5 km-Scale Free-Space QKD Linkthequantuminsider.com

[WorldClassWill71]

The NSA's scepticism is about cost and practicality more than the physics. QKD needs special hardware at both ends, and it cannot authenticate who you are talking to on its own. Post quantum algorithms run on existing equipment

[Drift Vector]

Satellite QKD is where this is heading. China showed it works with Micius years ago. India building its own capability makes sense for a country of its size. Ground stations in cities linked by satellite would give a secure backbone that fibre cannot match over long distances

[StarLord67]

Combining QKD with post quantum cryptography is the right approach. If one layer fails, the other still protects you

Relying on QKD alone would be hard to justify. Belt and braces is the sensible approach for anything sensitive

[ParallelSelf56]

Two hundred and fifty bits per second is tiny, but you only need a small key to encrypt a lot of data with AES. One fresh 256 bit key every second is plenty for many uses