University of Chicago Pritzker School of Molecular Engineering

February 24, 2021

In a breakthrough for quantum computing, University of Chicago researchers have sent entangled qubit states through a communication cable linking one quantum network node to a second node.

The researchers, based in the Pritzker School of Molecular Engineering (PME) at the University of Chicago, also amplified an entangled state via the same cable first by using the cable to entangle two qubits in each of two nodes, then entangling these qubits further with other qubits in the nodes.

The results, published February 24, 2021 in Nature, could help make quantum computing more feasible and could lay the groundwork for future quantum communication networks.

“Developing methods that allow us to transfer entangled states will be essential to scaling quantum computing,” said University of Chicago professor Andrew Cleland, who led the research.

Sending entangled photons through a network

Qubits, or quantum bits, are the basic units of quantum information. By exploiting their quantum properties, like superposition, and their ability to be entangled together, scientists and engineers are creating next-generation quantum computers that will be able solve previously unsolvable problems.

Cleland Lab uses superconducting qubits, tiny cryogenic circuits that can be manipulated electrically.

To send the entangled states through the communication cable – a one-meter-long superconducting cable – the researchers created an experimental set-up with three superconducting qubits in each of two nodes. They connected one qubit in each node to the cable and then sent quantum states, in the form of microwave photons, through the cable with minimal loss of information. The fragile nature of quantum states makes this process quite challenging.

Read more