Cisco sees headway in quantum networking, but advances are slow

The development of quantum networking technology will ultimately yield more secure and higher-speed connectivity, but it’s still very early in the game and many challenges remain before it becomes mainstream.

While core quantum networking technologies such as repeaters and photonics are being developed, it is security applications – specifically post-quantum cryptography (PQC) – that are likely to be the first real-world developments that come out of the lab, according to Liz Centoni, executive vice president, chief strategy officer and general manager of applications at Cisco. PQC, or quantum-safe cryptography, features complicated cryptographic algorithms that are expected to protect quantum computers from sophisticated attacks. 

“We will see adoption of post-quantum cryptography (PQC) – even before it is standardized – as a software-based approach that works with conventional systems to protect data from future quantum attacks,” Centoni wrote in a recent blog about core technology predictions for 2024 and beyond.

“PQC will be adopted by browsers, operating systems, and libraries, and innovators will experiment by integrating it into protocols such as SSL/TLS 1.3 which governs classic cryptography,” Centoni stated. “PQC will also start to trickle down to enterprises as they aim to ensure data security in the post-quantum world.” The need for such security is becoming critical now because of the concern that bad actors are already employing attack vectors in preparation for what quantum computers might be able to crack in years to come.

“There is a massive problem looming in front of us, and that is the whole ‘harvest now, decrypt later’ challenge,” said Vijoy Pandey, senior vice president of Cisco’s advanced research group Outshift. “For government, sensitive transactions, [and] financial institutions, security is a big deal and people are getting paranoid about this.”

So much so that an IBM executive at the World Economic Forum in Davos said: “Is quantum going to really create a cybersecurity Armageddon? It’s going to,” said Ana Paula Assis, IBM’s general manager of Europe, Middle East and Africa.

Pandey points out that no current quantum computer can do the type of security cracking that can cause concern – they are not powerful enough yet. But “the concern is that if an organization has a break-in they don’t know about, and traffic’s being redirected and stored somewhere for the day when a bad actor does have the capability to build a reasonably sized quantum node, they could just decrypt everything,” he said.

The flip side, however, is that future quantum computing developments could enable infallible security technologies that could protect data communications from any interference or snooping. There is ongoing work to build secure quantum environments at a variety of organizations, including Verizon, British Telecom, Ernst & Young, and government labs such as DARPA Quantum Networking Program and Los Alamos National Lab.

Quantum networking potential

Research and investment in developing quantum-safe networks is underway as well.

Cisco has said that it envisions quantum data centers that could use classic LAN models to tie together quantum computers, or a quantum-based network that transmits quantum bits (qubits) from quantum servers at high-speeds to handle commercial-grade applications.

“Another trend will be the growing importance of quantum networking which in 4 or 5 years – perhaps more – will enable quantum computers to communicate and collaborate for more scalable quantum solutions,” Centoni stated. “Quantum networking will leverage quantum phenomena such as entanglement and superposition to transmit information.”

The current path for quantum researchers and developers is to continue to grow radix, expand mesh networking (the ability for network fabrics to support many more connections per port and higher bandwidth), and create quantum switching and repeaters, Pandey said. “We want to be able to carry quantum signals over longer distances, because quantum signals deteriorate rapidly,” he said. “We definitely want to enable them to handle those signals within a data center footprint, and that’s technology we will start experimenting on.”

Pandoy said Cisco is building software simulators for this type of environment that it will make available as open-source software.

In addition, Cisco’s Quantum Lab is working on developing repeaters for quantum networks. Quantum repeater protocols are generally divided into two categories in terms of the type of required communications: two-way and one-way repeaters, Cisco explained in a blog post about its work in this area.

“Compared to one-way repeaters which require forward quantum error correction, two-way repeaters feature simpler quantum hardware and can handle longer distances but come with two drawbacks: latency and congestion,” Cisco wrote. “Nevertheless, until the advent of a compact quantum computer equipped with quantum error correction capabilities, two-way repeaters remain the preferred contender for long-distance quantum communication.”

A common theme in conventional repeater protocols is that the hardware is entirely designed for specific quantum codes and substantial changes need to be made to switch to another code, Cisco stated. “In our work, we bring all the complexity into a single device, the so-called resource state generator (RSG), which outputs multi-photon encoded qubits by sending pulsed laser through an array of interferometers and photon detectors. RSGs are fabricated on silicon photonic integrated circuits which are also a candidate platform for quantum computing.”

“This way, upgrading to a new quantum code would become a software update, i.e., reprogramming the photonic circuit. Such flexibility further leads to a long-term advantage as new generations of quantum codes will be available,” Cisco stated.

Other work at the Cisco Quantum Lab includes enabling quantum networks over existing fiber infrastructures. 

“Quantum networks use optical communication links. In envisioning a pragmatic and economical approach to constructing these networks, a compelling strategy is then to capitalize on our already established optical network infrastructure. The first step to build entanglement distribution networks in an existing infrastructure entails the art of identifying optimal sites for embedding quantum hardware,” Cisco wrote.