In fifty years, computer networks such as the Internet have advanced from academic curiosity to a fundamental infrastructure of the modern world. More recently, scientists have theorized that systems based on quantum mechanical phenomena could solve problems far beyond the reach of classical computers. Now, a research team led by the USC Viterbi Information Sciences Institute (ISI) seeks to bring these two fields together, to create secure, trustworthy, and robust networks that meet increasingly critical societal needs. 

A key aspect of the effort is its focus on real world impact. Rather than targeting a fully quantum internet, the team is building practical hardware and software to augment existing internet infrastructure with the unique properties of quantum mechanics. The goal is to deliver commercial-ready technologies within the next five years. 

“We aren’t exploring the very far away question of how to build networks that connect quantum computers together,” John Wroclawski, project co-principal investigator and senior director for strategic initiatives at ISI, said. “Instead, our question is: can quantum technologies, as they exist today or in the near future, fundamentally improve the trustworthiness of current networks?” 

The team, a collaboration between ISI, USC, NuCrypt LLC, MIT, and Northeastern University, calls their project AQUARIUS, an acronym for Accelerated Quantum Research Integration for Usable Secure Networks. They have received $18 million in support from the Defense Advanced Research Projects Agency (DARPA), announced in May 2024.

The funds will be used to develop two key innovations: a novel hardware component, known as a quantum-augmented network interface card, and a novel software framework to integrate this and other hardware into existing systems. Together, these technologies could enable what the researchers call “quantum-augmented networking”—a way to enhance classical networks with completely new security and trustworthiness properties not available through existing approaches.

A new kind of network interface

Central to the AQUARIUS project is the development of a quantum-augmented network interface card, or QNIC. In classical networking, standard network interface cards (NICs) connect devices such as PCs and servers to the internet. AQUARIUS’s QNIC takes this concept further, integrating quantum functions into the NIC to enhance network security and performance.

The project investigators say that this is a completely new capability. “Nobody’s ever built one of these before, nor knows what they’re going to look like,” Wroclawski said.

At the level of quantum physics, the QNIC achieves its functionality by leveraging what the team calls “practical quantum states”—weak states of laser-generated light that exhibit quantum properties. “These states are limited in capability compared to some other quantum approaches, but still offer essential properties for our application” explains Jonathan Habif, a principal scientist at ISI and project co-principal investigator. “In return, their huge benefit is that no esoteric technology is required to work with them. A fundamental part of our idea is that we can build a QNIC today, with materials we can buy off-the-shelf,” said Habif.

Stephen Schwab, a research director at ISI and project principal investigator, said that the QNIC could layer these properties over existing channels and connections, providing extra security for everything from Zoom calls to bank transfers. “Everyone’s computers could potentially get quantum-augmented services with our solution,” he said.

Software that makes it work

Hardware innovations like the QNIC are only part of the equation. To ensure seamless integration into existing networks, the AQUARIUS team is also designing a universal software stack. This framework decouples the functionality of the software from the design of the hardware—a concept known in computer science as abstraction.

“Abstraction layers hide the complexity of underlying systems, making it easier for developers to work with higher-level concepts without needing to understand the intricate details of a particular lower-level implementation” Wroclawski explained. “This is key, because it means our approach can support future QNICs and quantum augmented services, not just the ones we’re building today.”

This is already at play in today’s internet. Web developers don’t need to know the inner workings of various network cards to build websites. That abstraction helped the internet take off, making new innovations accessible and scalable. The AQUARIUS framework could have a similar impact on quantum-augmented technologies.

“The team wants to implement an overall software framework that facilitates rapid advancement and wide-scale deployment of quantum-augmented networking services,” said David Balenson, interim director of ISI’s networking and cybersecurity division, who is not involved in the project.

The ISI legacy, in action

DARPA has funded multiple research teams to explore solutions for quantum-augmented networking. However, only the AQUARIUS team is tackling both hardware and software.

If successful, the software stack will unify all emerging prototypes, each with their own unique designs and functionalities, under one umbrella. This could enable disparate research teams to integrate their quantum-augmented technologies, including QNICs, into a cohesive system. In the future, it could also allow hardware to evolve and advance over time without requiring constant software changes.

That the AQUARIUS team is attempting to create both the QNIC and the universal software stack is a testament to ISI’s history and expertise. The institute was instrumental in developing the classical internet and has remained at the forefront of networking and cybersecurity projects for decades.

“At ISI, there’s a certain depth of knowledge about what it means to build a network,” Schwab said. “It’s part of the DNA of the institution.”