Cisco has unveiled research prototypes that aim to network quantum computers together, enabling both advanced quantum and classical applications.

Designed by Cisco Quantum Labs, the prototypes include a distributed quantum compiler enabled for networked quantum data centers, enabling the efficient execution of quantum algorithms across interconnected machines.

The compiler takes quantum circuits, which represent the compiled form of quantum algorithms, and partitions, schedules, and distributes them across multiple quantum processors in a data center. This enables workloads larger than a single quantum computer can handle, while also supporting distributed error correction.

Hybrid theory

The second prototype, dubbed Quantum Alert, leans more toward Cisco’s cybersecurity heritage. The demo uses entangled photons to detect eavesdropping attempts, with quantum networking establishing a channel where any interceptions are detectable due to the fragility of quantum states.

Quantum Alert complements existing encryption methods, including post-quantum cryptography (PQC) of the sort recently implemented by F5 and Palo Alto Networks.

Cisco’s hybrid approach of combining classical and post-quantum cryptography has also been adopted by its peers. In a recent interview with SDxCentral, Peter Scheffler, senior solutions architect for F5, said the firm is encouraging hybrid key establishment at the transport layer security (TLS) level between client and server.

“[It’s] a mix of both classical and post-quantum methods in the same TLS handshake as we don't know if these will be secure in the future. PQC has been tested but it's new,” said Scheffler.

Quantum security experts such as Dr Axel Y Poschmann, VP of product at PQShield, also believe security teams should be acting now instead of waiting for the arrival of Q-Day, the projected event three to six years from now of a quantum computer becoming powerful enough to break encryptions.

“The first step is to protect long-lived confidential data, which is most susceptible to harvest-now, decrypt-later attacks,” the VP told SDxCentral.

As such, Cisco's Quantum Alert prototype includes an additional layer of defense against harvest-now, decrypt-later attacks, alongside any software-based protection.

Quantum entanglement

The third and final Cisco prototype, Quantum Sync, leverages quantum entanglement to coordinate correlated decisions across distributed locations for classical applications

In quantum entanglement, particles become linked, so that the state of one instantly relates to the state of another. This means that rather than transmitting information directly, it can allow multiple parties to correlate their outcomes without explicit communication. Cisco’s prototype highlights how this quantum feature could be applied to distributed systems, where synchronization is often complex and costly.

Earlier this year, the security giant unveiled a prototype quantum network entanglement chip, designed by its incubation division Outshift in collaboration with UC Santa Barbara.

“Today’s quantum computers are stuck at hundreds of qubits when real-world applications need millions,” wrote Vijoy Pandey, GM and SVP of Cisco's Outshift. “We can either wait decades for perfect quantum processors, or we can network existing ones together now.

“Just as we did for the classical internet, we’re building a full networking stack from the ground up: developing a quantum networking chip, control software including protocols and controllers for managing the network, and quantum networking applications that solve problems in the quantum and classical worlds.

"Our approach works with any quantum computing platform, whether superconducting, trapped ion, photonic or any other.”