Quantum technology dangles a tantalizing vision of an internet where information is inviolate and hackers fear to tread, knowing they can’t escape detection.
Commonwealth Cyber Initiative (CCI) researchers at Virginia Tech are advancing this vision by exploring quantum networks, which are poised to revolutionize cybersecurity thanks to the uncanny behavior of physics at the quantum level.
“For a long time, these ideas were just curiosities, completely unintuitive,” said Sophia Economou, Virginia Tech professor of physics in the College of Science. “Now we are potentially turning them into technology.”
Leading a cross-disciplinary team that includes CCI Virginia Tech researchers Edwin Barnes from physics and Jamie Sikora from computer science as well as Nicholas Mayhall from chemistry, Economou is navigating a path from quantum curiosity to quantum technology in her role as director of the Virginia Tech Center for Quantum Information Science and Engineering.
Administratively housed under the Institute for Critical Technology and Applied Science (ICTAS), the center collaborates with groups such as the Commonwealth Cyber Initiative’s Southwest Node, the National Security Institute, the Innovation Campus, and the Corporate Research Center, all of which are investing in quantum research and infrastructure.
A bit is the smallest unit of digital information, and it exists in one of two states: 0 or 1. In a quantum information processor, information is packaged in quantum bits (qubits) that simultaneously occupy multiple states between 0 and 1 — states that can’t be accessed by a regular information processor. This quality, called superposition, unlocks unprecedented computational power and processing speed.
What could this magnitude of power mean? For a start, researchers from every field could tackle data-hungry monster problems that even the most advanced computers can’t solve — problems such as molecular simulations for life-saving medical developments, weather and atmospheric modeling in a changing climate, and securing a planet’s worth of sensitive information.
But quantum computing is not the only transformative quantum technology in the works. Quantum systems have properties that provide inherent security in communications. Unlike “classical” networks, which comprise the existing internet, quantum networks will enhance cybersecurity and allow a host of cryptographic and networking tasks.
“The implication of quantum networks on cybersecurity is nothing short of transformative,” said Gretchen Matthews, Virginia Tech math professor and director of CCI’s Southwest Node. “We’re looking at new paradigms with widespread impact. Quantum networks will provide access to these new computational tools.”
Quantum networks aren’t here yet — but they’re getting closer.
“We already have proof of principle for quantum networks,” said Economou. “This means that small-scale quantum networks already exist. We are trying to solve very hard technological and engineering problems, but proof of principle works — we know that.”
Safe access via quantum networks
In the future, a user will be able to securely access a quantum computer via a quantum network. This is analogous to running a program on the cloud, said Economou. Even an old laptop can connect to Amazon servers, for example, and tap into a huge reservoir of computing power. The key difference for quantum networks is security: a user may want to run a program that needs to be keep secret, maybe for intellectual property or national security reasons.
“Quantum networks allow you to send qubits that securely encode the algorithm you want to solve so that even the person who owns or operates the quantum computer doesn’t know what you’re doing,” said Economou.
How does this work? By exploiting the spooky nature of quantum mechanics.
Unraveling a quantum Catch-22
Funny thing about qubits: You can’t measure them without dramatic consequences, said Economou. If you meddle with a qubit — and this includes attempting to copy it — the quantum state is modified, which essentially guarantees inherent security for a quantum network.
“To test the security of an exchange, one user can send a packet of information as a trial,” said Economou. “If it doesn’t match the information received, you can assume that someone in the middle is trying to measure or intercept the information.”
This anti-meddling quantum booby trap presents a new problem: The classical network relies on strategically placed repeaters to measure and amplify the signal — not an option for a qubit.
“You need to something cleverer,” said Economou.
With initial funding from the Commonwealth Cyber Initiative in Southwest Virginia, Economou and her team are working on the “something more clever.”
“The solution, which was put forward many years ago, is something called entanglement,” she said. “We are exploring how to use entanglement to build and extend a quantum network.”
Entanglement is when two or more qubits physically interact to become correlated and stay correlated even if they are separated — like stories of identical twins who can feel each other’s pain or pleasure even miles apart.
In a quantum network, a user at one node can manipulate the entangled system, which would automatically update the counterpart at a different point — essentially teleporting information across a network without actually transmitting a physical qubit.
Economou and her team are exploring how to create and distribute entangled quantum states — a process that involves sending entangled photons through a series of waystations. The team theorizes that it’s possible to measure (and thus destroy) a subsystem of the entangled qubits. This would allow team members to correct and adjust for inevitable errors and then slingshot the information up to the next waystation without compromising it.
By looking at how information processing all the way down at the atomic level can impact a quantum network as a whole, Economou and her collaborators are designing the architecture that may one day secure our everyday communications and securely connect us to the power of quantum computation.