On the 8th, the online version of Nature Communications magazine published a breakthrough research achievement by Finnish scientists: they have developed a quantum circuit refrigeration device called a "nanorefrigerator", which can keep quantum bits at a sufficiently low temperature to operate accurately and reliably. Researchers say that this type of refrigerator can be integrated into various quantum electrical devices, including quantum computers, in the future.
Ordinary computers use 0s and 1s to store information, which can be cooled by cooling fans or hoods. Quantum computers use quantum bits to store information, which are binary quantum systems formed by the superposition of two energy states. Due to the sensitivity of stacked quantum bits to external interference, even slight interference can damage them and cause computational errors. Therefore, it is necessary to isolate them well from external interference. But quantum bits are easily heated up after isolation, which can have an impact on quantum computers.
Quantum computers involve thousands of qubits simultaneously in performing fast operations. In order to ensure accurate calculation results, quantum bits must be initialized to a low-temperature energy state before starting an algorithm. If the quantum bits overheat, initialization cannot be achieved, making it difficult to switch quickly when running multiple quantum algorithms.
In response to the above issues, quantum physicist Miko Merton and colleagues at Aalto University in Finland have developed a quantum circuit cooler. Quantum circuits form energy bands through two independent electron tunnels, one is a superconducting fast channel that allows electrons to pass through with zero resistance, and the other is a non superconducting slow channel. Electrons in the slow channel can absorb excess heat from nearby quantum devices and transition to the superconducting channel. High temperature electrons jump over the energy band, while low-temperature electrons "stay" down, just like the refrigeration mechanism of a refrigerator, taking away the heat inside the quantum system.
In the testing experiment, the quantum refrigeration device successfully cooled down the quantum superconducting resonator. By adjusting the external voltage, the switch control of cooling can be achieved. Next, the research team will improve the nanocooler and test its cooling effect on actual quantum sites.
Merton said that the new nanocooler is expected to be commercialized within 5 to 10 years, allowing future quantum devices to quickly switch between different algorithms when performing computing tasks, improving their computing power and reliability.