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Quantum computers get automatic error correction for the first time
Quantum computers could use heat to eliminate errorsChalmers University of Technology, Lovisa HkanssonA 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 arent yet fully practical because they make too many errors. In fact, if qubits key components of this type of computer accidentally heat up and become too energetic, they can end up in an erroneous state before the calculation even begins. One way to reset the qubits to their correct states is to cool them down. AdvertisementSimone Gasparinetti at Chalmers University of Technology in Sweden and his colleagues have delegated this task to an autonomous quantum refrigerator for the first time.The researchers built two qubits and one qutrit, which can store more complex information than a qubit, from tiny superconducting circuits. The qutrit and one of the qubits formed a fridge for the second target qubit, which could eventually be used for computation.The researchers carefully engineered the interactions between the three components to ensure that when the target qubit had too much energy, which caused errors, heat automatically flowed out of it and into the two other elements. This lowered the target qubits temperature and reset it. Because this process was autonomous, the qubit-and-qutrit fridge could correct errors without any outside control. Receive a weekly dose of discovery in your inbox.Sign up to newsletterAamir Ali, also at Chalmers University of Technology, says this approach to resetting the qubit required less new hardware than more conventional methods and yielded better results. Without any significant quantum computer redesign or introduction of new wires, the qubits starting state was correct 99.97 per cent of the time. In contrast, other reset methods typically only manage 99.8 per cent, he says.This is a powerful example of how thermodynamic machines which deal with heat, energy and temperature can be useful in the quantum realm, says Nicole Yunger Halpern at the National Institute of Standards and Technology in Maryland, who worked on the project.Conventional thermodynamic machines like the heat engine sparked a whole industrial revolution, but so far quantum thermodynamics hasnt been very practical. Im interested in making quantum thermodynamics useful. This arguably useful autonomous quantum refrigerator is our first example, says Yunger Halpern.Its nice to see this machine implemented and useful. The fact that it is autonomous, so it does not require any external control, should make it efficient and versatile, says Nicolas Brunner at the University of Geneva in Switzerland.Micha Horodecki at the University of Gdask in Poland says that one of the most urgent problems for quantum computers built with superconducting circuits is making sure the machines dont heat up and subsequently make errors. The new experiment opens a path 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 could build on their experiment. For example, they might create an autonomous quantum clock or design a quantum computer with other functions automatically driven by temperature differences.Journal referenceNature Physics DOI: http://dx.doi.org/10.1038/s41567-024-02708-5Topics:
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