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Quantum computing saves energy by processing complex computations much more efficiently than traditional computers, but the overall energy efficiency of quantum computing is still uncertain.
The new Google has recently installed a 1,000-qubit D-Wave quantum computer at its Quantum AI Lab, which is considered to be one of the world’s first commercial quantum computers. The appeal of quantum computers lies within their power to make complex computations at significantly quicker speeds than conventional computers.
Workings of Quantum Computing
Quantum computing relies on qubits rather than transistors to relay data, and these qubits can essentially code information as both 1s and 0s, rather than the binary 1 or 0 coding of computing using transistors. This simple difference allows quantum to process information in parallel, and in theory, this gives quantum the power to process information at staggering speeds, allowing quantum to solve problems outside of the realm of traditional computing but without relying on an increase in energy to do so.
The method of how quantum computing works leads to the assumption that quantum computing would also be more energy-efficient. By some estimations, quantum has the ability to reduce energy consumption from 100 up to 1000 times through its use of quantum tunneling to process data. So, it makes sense to believe that the quantum computer will require less energy than the traditional computer.
However, there is a requirement of quantum computing that requires a lot of energy, and that’s refrigeration. The quantum processor needs to be kept at a very low temperature, lows of around 15 millikelvin (-273° C), in order to function.
To put that into perspective, 15 millikelvin is colder than interstellar space. This level of low temperature is required in order to facilitate superconducting within the processor, and with superconducting, the electricity can be conducted through the processor with almost no resistance. While superconducting minimizes the amount of energy needed for processing, relying on just a fraction of what traditional computers use, it requires a lot of energy to keep cool.
Google’s D-Wave Computer
Google’s D-Wave computer, for example, uses just under 25 kilowatts of energy to power the hardware, but much of this power is going directly to keeping the quantum processor cool enough to work. In fact, the energy consumed by the quantum processor has been described as being negligible when compared to the power consumed by the refrigerator.
While the quantum processor needs significantly less energy to work, it also needs significantly more energy in the form of powering the refrigeration unit, which traditional computers do not need. This has raised concerns about the overall energy efficiency of quantum computing.
However, experts in the development of quantum computing have diminished concerns about the energy requirements of the refrigeration system. It is explained that as quantum processors become more powerful, they won’t need more energy to cool them down. So processing power can exponentially increase without the need to boost refrigeration.
For example, Google’s new D-Wave computer uses about double the number of qubits as the previous model. However, the same “cryostat” unit is sufficient to cool both. As larger quantum processors are developed, the “cryostat” will not need to grow, and therefore the energy used to power larger computers will not grow.
Future of Quantum Computing
The future of quantum computing looks promising in terms of its ability to reduce energy consumption. While energy dependant refrigeration systems are required to keep the machines cool enough to support superconducting, these systems will not need to grow as the processing power increases, opening up the possibility of rapidly growing processing power for the same energy cost.