When the quantum internet arrives, researchers predict it will shift the computing landscape on a scale unseen in decades. In their estimation, it will make hacking a thing of the past. It will secure global power grids and voting systems. It will enable nearly limitless computing power and allow users to securely send information across vast distances.
But for Tian Zhong, assistant professor at the Pritzker School of Molecular Engineering (PME) at the University of Chicago, the most tantalizing benefits of the quantum internet have yet to be imagined.
Zhong is a quantum engineer working to create this new global network. In his mind, the full impact of the quantum internet may only be realized after it’s been built. To understand his work and why the United States is spending $625 million on the new technology, it helps to consider the science behind it: quantum mechanics.
Quantum mechanics is a theory created to explain fundamental properties of matter, particularly on the subatomic scale. Its roots trace back to the late 19th and early 20th century, when scientists tried to explain the unusual nature of light, which behaves as both a wave and a particle. In the hundred years since then, physicists have learned a great deal, particularly concerning the strange behavior of subatomic particles.
They’ve learned, for example, that some subatomic particles have the ability to be in two states at the same time, a principle called superposition. Another such principle is entanglement, which is the ability of two particles to “communicate” instantaneously despite being separated by hundreds of miles.
Over time, scientists have found ways to manipulate those principles, entangling particles at will or controlling an electron’s spin. That new control allows researchers to encode, send, and process information using subatomic particles—laying the foundations of quantum computing and the quantum internet.
At the moment, both technologies are still hampered by certain physical limitations—quantum computers, for example, need to be kept in giant sub-zero freezers—but researchers like Zhong are optimistic those limitations will be resolved in the near future.
“We’re at a juncture where this is no longer science fiction,” Zhong said. “More and more, it’s looking like this technology will emerge from laboratories any day, ready to be adopted by society.”
The right tools for the job
Zhong’s research focuses on the hardware needed to make the quantum internet a reality, things like quantum chips that encrypt and decrypt quantum information, and quantum repeaters that relay information across network lines. To create that hardware, Zhong and his team work on the subatomic scale, using individual atoms to hold information and single photons to transmit it through optic cables.
Zhong’s current work centers on finding ways to fight against quantum decoherence, which is when information stored on a quantum system degrades to the point that it’s no longer retrievable. Decoherence is an especially difficult obstacle to overcome because quantum states are extremely sensitive and any outside force—be it heat, light, radiation, or vibration—can easily destroy it.
Most researchers address decoherence by keeping quantum computers at a temperature near absolute zero. But the instant any quantum state is transmitted outside the freezer, say on a network line, it begins to break down within a few microseconds, severely limiting the potential for expansive interconnectivity.