Researchers from Cisco report there are substantial efforts underway now to develop practical quantum networks and data centers.
Cisco Research recently hosted its Quantum Summit 2024 gathering that drew industry experts to discuss ongoing work focused on everything quantum from networking to security, but it was research being done in the quantum data center that garnered most of Cisco’s focus.
The quantum data center that Cisco envisions would have the capability to execute numerous quantum circuits, feature dynamic network interconnection, and utilize various entanglement generation protocols, stated Reza Nejabati, head of quantum research at Cisco’s advanced development group Outshift, in a presentation at the event.
“It is well known in academic research that quantum computing cannot become useful by monolithically scaling it to 10s of millions of qubits—that is not practical,” Nejabati said.
“It seems, at least with the current technology, it is more realistic to build a network of smaller quantum computers. And essentially you develop the notion of the data center—that is we build a network connecting a large number of smaller processors in a controlled environment, the data center warehouse, and provide them as a service to a larger user base. That’s the basic definition of a quantum data center,” Nejabati said.
Cisco said earlier this year it envisions quantum data centers that could use classic LAN models and fiber links 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.
“At the same time, you want to get to the position that you can connect your quantum sensors together and essentially bring in things like IoT and other sensor devices and connect them using a network, not only to get the benefit of better sensing and accuracy but also to have a distributed sensing in terms of the coverage area,” Nejabati said.
The idea is to not make customers reinstall a new type of network infrastructure for this work, rather it would be better to use the existing fiber infrastructure, at least for quantum entanglement, and then add control and management on top, Nejabati said.
In terms of networking, management, and control, Cisco is developing its own quantum entanglement network fabric called QFabric, which would be the core of a quantum switch and ensure the quantum entanglement process works between a quantum computer and sensor interconnect, Nejabati said. The switch supports non-blocking switching of entangled photons from any input ports to any output ports and supports multiple modes of entanglement. It will feature ultra-low loss and time jitter port-to-port switching to ensure connectivity.”
“Ultimately we want to support large numbers of users in a scalable, multi-tenant environment with this dynamically switched quantum network,” Nejabati said.
In addition to the networking functions, QFabric is the environment that will be used to ensure quantum-safe networking. For example, QFabric is very suitable for a scalable key distribution.
“We are working to build a platform that you can create a hybrid key management, key distribution system that brings together [post-quantum cryptography] PQC and [quantum key distribution] QKD,” Nejabati said. “Furthermore, any security solution relies on a random number generator, and a perfect random number generator is essential for cryptography, and at Cisco, we have our own internally developed quantum random number generator.”
PQC features complicated cryptographic algorithms that are expected to protect quantum computers from sophisticated attacks.
“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,” Cisco 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.
On top of the quantum network fabric effort, Cisco is developing a software package that includes the best way for entanglement, distribution effort, protocol, and routing algorithms, which the company is building in a protocol stack and compiler, called Quantum Orchestra.
“We are developing a network-aware quantum orchestrator, which is this general framework that takes quantum jobs in terms of quantum circuits as an input, as well as the network topology, which also includes how and where the different quantum devices are distributed inside the network,” said Hassan Shapourian, Technical Leader, Cisco Outshift. “The orchestrator will let us modify a circuit for better distributability. Also, we’re going to decide which logical [quantum variational circuit] QVC to assign to which quantum device and how it will communicate with which device inside a rack.”
“After that we need to schedule a set of switch configurations to enable end-to-end entanglement generations [to ensure actual connectivity]. And that involves routing as well as resource management, because, we’re going to share resources, and eventually the goal is to minimize the execution time or minimize the switching events, and the output would be a set of instructions to the switches,” Shapourian said.
According to Shapourian, most of the work Cisco has undertaken so far with the Orchestrator has been simulations to find out if multi-tenancy and other functions such as delivering data via multiple quantum paths rather than point-to-point are working together. The vendor is supposed to release a paper on the results later this year.