Quantum computers can use heat to eliminate errors
Chalmers University of Technology, Lovisa Håkansson
A tiny cooling device can automatically reset malfunctioning components of a quantum computer. Its performance suggests that manipulating heat could also enable other autonomous quantum devices.
Quantum computers they have not yet been fully practical they make too many mistakes. In fact, if the qubits – the essential components of this type of computer – accidentally heat up and become too energetic, they can end up in a wrong state before the calculation starts. One way to “reset” the qubits to their correct states is this cool them down.
Simone Gasparinetti At Chalmers University of Technology in Sweden and his colleagues, this task has been entrusted to an autonomous quantum “refrigerator” for the first time.
The researchers built two qubits and a “qutrit,” which can store more complex information than a single qubit, from tiny superconducting circuits. The qutrite and one of the qubits formed a refrigerator for the second target qubit, which could eventually be used for computation.
The researchers carefully designed the interactions between the three components to ensure that when the target qubit had too much energy, causing errors, heat would automatically flow from it and to the other two elements. This lowered and reset the temperature of the target qubit. Because this process was autonomous, the qubit-and-qutrit refrigerator could correct errors without any external control.
Aamir AliAlso at Chalmers University of Technology, he says this approach to resetting the qubit required less new hardware than more conventional methods and produced better results. Without any major quantum computer redesigns or new strings introduced, the qubit’s initial state was correct 99.97 percent of the time. In contrast, other recovery methods typically manage only 99.8 percent, he says.
This is a powerful example of how thermodynamic machines – dealing with heat, energy and temperature – can be useful in the quantum field, he says Nicole Yunger Halpern at the National Institute of Standards and Technology in Maryland, who worked on the project.
Conventional thermodynamic machines like heat engines sparked the entire industrial revolution, but quantum thermodynamics has not been very practical until now. “I’m interested in making quantum thermodynamics useful. It is arguably our first example of a useful self-contained quantum refrigerator,” says Yunger Halpern.
“It’s nice to see this machine implemented and useful. In fact, being autonomous therefore does not need external control, it should make it efficient and versatile,” he says. Nicolas Brunner at the University of Geneva in Switzerland.
Michał Horodecki At the University of Gdańsk in Poland, he says one of the biggest problems with quantum computers built with superconducting circuits is making sure the machines don’t. warm up and then make mistakes. The new experiment paves the way for many similar projects that have been proposed but never tested, such as using qubits to build autonomous quantum engines, he says.
The researchers are already looking into whether they can build their own experiment. For example, they can create a freelancer quantum clock or design a quantum computer with other functions automatically driven by temperature differences.
Topics:
