First successful implementation of automatic error correction on a quantum computer

A small cooling device can automatically reset malfunctioning components in a quantum computer. Its performance suggests that manipulating heat may also enable other autonomous quantum devices.

Quantum computers are not yet fully operational because they have too many errors. In fact, if a qubit, a key component of this type of computer, is accidentally heated and has too much energy, it can end up in an incorrect state before calculations can even begin. One way to “reset” a qubit to the correct state is to cool it.

Simone Gasparinetti For the first time, researchers at Sweden's Chalmers University of Technology have delegated this task to an autonomous quantum “fridge.”

Researchers have constructed two qubits and a single qubit, which can store more complex information than a quantum bit, from a tiny superconducting circuit. The qutrit and one of the qubits form a refrigerator for the second target qubit, which can eventually be used for computation.

The researchers investigated the interaction between the three components so that if the target qubit has too much energy and an error occurs, heat automatically flows out of the qubit and into the other two elements. carefully designed. This lowered the temperature of the target qubit and reset it. Because this process is autonomous, qubits and quantum trit refrigerators were able to correct errors without external control.

aamir aliThe researchers, also at Chalmers University of Technology, said this approach to resetting qubits required less new hardware and produced better results than traditional methods. Without a major redesign of the quantum computer or the introduction of new wires, the starting state of the qubit would be accurate 99.97% of the time. In contrast, other reset methods typically only manage 99.8%, he says.

He said this is a powerful example of how thermodynamic machines, which deal with heat, energy, and temperature, can be useful in the quantum realm. nicole junger halpern I worked on this project at the National Institute of Standards and Technology in Maryland.

Traditional thermodynamic machines like heat engines sparked an entire industrial revolution, but so far quantum thermodynamics hasn't been very practical. “We are interested in making quantum thermodynamics useful, and this potentially useful autonomous quantum refrigerator is our first example,” says Jünger Halpern.

“I'm glad that this machine has been implemented and has become useful. Being autonomous, it does not require external control and should be efficient and versatile,” he says. Nicholas Bruner at the University of Geneva, Switzerland.

Michał Holodeck Researchers at the University of Gdańsk in Poland say one of the most pressing problems for quantum computers built with superconducting circuits is to keep the machines from overheating and causing errors. He says the new experiment paves the way for many similar projects that have been proposed but untested, such as using qubits to build autonomous quantum engines.

The researchers are already considering whether they can take the experiment further. For example, we might create autonomous quantum clocks or design quantum computers with other functions that are automatically driven by temperature differences.