Advanced cooling technology could help revitalize quantum computing and cut costly preparation time in key science experiments by weeks.
Scientists often need to generate temperatures close to… Absolute zero For quantum computing and astronomy, among other uses. These temperatures are known as the “big cold”, as they keep the most sensitive electrical devices free of interference – such as temperature changes. However, the refrigerators used to achieve these temperatures are very expensive and inefficient.
However, scientists at the National Institute of Standards and Technology (NIST) – a US government agency – have built a new refrigerator prototype that they claim can achieve significant cooling more quickly and efficiently.
The researchers published details of their new machine April 23 in the journal Nature Communications. They claimed that its use could save 27 million watts of energy annually and reduce global energy consumption by $30 million.
A new generation of refrigerators
Traditional household refrigerators work through a process of evaporation and condensation Live sciences. The refrigerant is forced through a special low-pressure tube called an “evaporator coil.”
As it evaporates, it absorbs heat to cool the interior of the refrigerator and then passes through a compressor that turns it back into a liquid, raising its temperature as it radiates through the back of the refrigerator.
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To achieve the desired temperatures, scientists have used pulsed tube refrigerators (PTRs) for more than 40 years. PTR devices use helium gas in a similar process but with better heat absorption and no moving parts.
Although effective, it consumes huge amounts of energy, is expensive, and is time-consuming to operate. However, NIST researchers also discovered that PTR devices are unnecessarily inefficient and could be significantly improved to reduce cooling times and lower overall cost.
In the study, the scientists said that PTR devices “suffer from significant shortcomings” such as being optimized “for performance only at the core temperature” — typically close to 4 Kelvin. This means that during cooling, the PTRs operate at largely inefficient levels, they added.
The team found that by modifying the PTR design between the compressor and the refrigerator, helium was used more efficiently. During cooling, some of it is usually forced into a relief valve instead of being pushed around the circuit as intended.
Quantum computing at a fraction of the cost
The proposed redesign includes a valve that deflates as the temperature decreases to prevent any helium from being wasted in this way. As a result, the NIST team’s modified PTR achieved the Big Chill score 1.7 to 3.5 times faster, the scientists said in their paper.
“In smaller experiments modeling quantum circuits where cooling times are currently comparable to characterization times, dynamic acoustic optimization can significantly increase measurement throughput,” the researchers wrote.
The new method could save at least a week of experiments at the Cryogenic Underground Observatory for Rare Events (CUORE) — a facility in Italy used to look for rare events like the current theoretical form of radioactive decay, the researchers said in their study. As little background noise as possible must be achieved to obtain accurate results from these facilities.
Quantum computers need a similar level of isolation. They use quantum bits, or qubits. Traditional computers store information in bits, encode data with a value of either 1 or 0, and perform calculations sequentially, but qubits occupy a superposition of 1 and 0, thanks to the laws of Quantum mechanicsThey can be used to process calculations in parallel. However, qubits are incredibly sensitive and must be separated from as much background noise as possible, including small fluctuations in thermal energy.
More efficient cooling methods could theoretically be achieved in the near future, which could lead to faster innovation in quantum computing, the researchers said.
The team also said their technology could instead be used to achieve ultra-cold temperatures at the same time but at a much lower cost, which could benefit the cryogenics industry, cutting costs for experiments and industrial applications that don’t take as long. Scientists are currently working with an industrial partner to commercially release the improved PTR.
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