Scientists Just Teleported a Quantum Gate for the First Time

Teleportation—the ability to transfer matter or energy from one point to another without moving through physical space—is a staple of science fiction. But in the world of quantum physics, it has now become a reality.

Scientists from Yale have just teleported a quantum gate between two qubits on demand and without the need for direct interaction—a fundamental breakthrough for the development of quantum computers of the future.

In a study published in Nature, the team says it looking to solve one of the big problems in quantum computing: the errors that are introduced by quantum computing processors. "A quantum computer has the potential to efficiently solve problems that are intractable for classical computers," the team wrote. "However, constructing a large-scale quantum processor is challenging because of the errors and noise that are inherent in real-world quantum systems."

One way to cut out these errors is to use modularity.

Modularity is found throughout nature—from the organization of a biological cell through to the most complex feats of technology. It relates, as implied in the name, to the compartmentalization of individual parts to create a whole. This approach, the scientists say, helps to manage complexity and uncertainty and so could be useful to the development of quantum systems connected to a quantum network via communication channels. It would prevent unwanted interactions thought the wider system—qubits, which carry out quantum calculations, are prone to errors, which makes performing operations between different modules is challenging.

So essential to this approach is the teleportation of a quantum gate—this would allow interactions without the risk of errors being introduced in the transfer. This idea was first proposed as a theoretical approach in the 1990s. The Yale scientists have now demonstrated it in a real-world experiment.

"Our work is the first time that this protocol has been demonstrated where the classical communication occurs in real-time, allowing us to implement a 'deterministic' operation that performs the desired operation every time," study co-author Kevin Chou said in a statement.

This has big implications for the development of "fault-tolerant quantum computation," the scientists say. "And when realized within a network it can have broad applications in quantum communication, metrology and simulations," they add.

Principal investigator Robert Schoelkopf said: "It is a milestone toward quantum information processing using error-correctable qubits."

Professor Myungshik Kim, Chair in Theoretical Quantum Information Sciences at the U.K.'s Imperial College London, described the study as a "significant step forward" in the development of quantum computers.

He told Newsweek the imperfections of gate operations is one of the big problems in building a quantum computer. "The Yale researchers led by Schoelkopf has shown how to accurately perform controlled-NOT operations between two remote quantum bits located in separate modules. In their work, quantum bits are realised by superconductors. They applied the idea of quantum teleportation for this.

"An important breakthrough is that they minimized the use of operations and resources so to reduce imperfections and operating times. The accuracy of the operation which is around 95 percent should be improved significantly to the level required, normally above 99.99 percent. However, the Schoelkopf's experiment is a significant step forward to realize a quantum computer using superconducting devices."

Update: This story has been updated to include quotes from Myungshik Kim.