Quantum for sustainability
Wait, quantum for sustainability, how is that supposed to work? Well, there are two different ways to look at it. First, there are endless ways in which powerful simulations realized by quantum computing will allow us to optimize resources and minimize the CO2 footprint. And secondly, there is the fact that quantum computers are more sustainable in and of themselves, primarily due to their (energy) efficiency. This may seem counter-intuitive because quantum computers must be cooled to about absolute zero, which equals about -273 degrees Celsius. And yet, the physical structure, which is entirely new compared to traditional computers, leads to an entirely different overall energy balance.
But let’s look at sustainable solutions created through quantum computing first …
Sustainable solutions through quantum
No matter in which industry, quantum computing can be leveraged to address three types of computationally intensive problems: machine learning, simulation, and optimization. Compared to today’s high-performance computers, the performance boost creates disruptive potential towards achieving climate neutrality much sooner.
For example, in the energy sector: power grids, which are increasingly heterogeneous and decentralized due to renewable energy, represent a high-dimensional optimization problem that must be solved continuously to smooth out peaks and use the available energy optimally. Such an optimization task cannot be solved in real-time on classical computers, but it will have to be in an age of decentralized power generation and consumption. Quantum will be there to help!
Or think about the chemical and pharmaceutical industry. Complex molecules and their interactions with other substances can be efficiently simulated on quantum computers. In drug discoveries, this will allow us to evaluate new substances in an early development phase which shortens the development of vaccines, for instance, thereby reducing the environmental impact (and costs) tremendously. Or in computational chemistry, where we will be able to optimize processes in chemical reaction networks or discover new materials through molecular modeling, for example, invent more environmentally friendly fertilizer solutions.
These are just some examples, but there are many more. Think traffic flow or supply chain optimization, new battery development, industrial manufacturing with less material waste, etc.
But now, let’s take a look at the less obvious aspect of quantum for sustainability: the energy-efficiency potential of quantum computers.
Sustainability of quantum computers
First, let’s look at a simplified quantum computer setup and the corresponding energy requirements. Essentially, a quantum computer comprises two components, quantum electronics, and a control circuit. The quantum electronics circuit is the computer's actual “quantum” part. It includes the processor, wiring, and so on – plus, most importantly, this component must be operated at temperatures at about absolute zero. On the other hand, the control circuit is based entirely on traditional engineering and classical computing architecture. This is where you control the quantum computer, run applications, do noise correction, etc. Since conventional electronics operate this, it can be operated at about room temperature.
Now, for energy requirements: Cooling the quantum electronics circuit certainly dominates the overall power usage of quantum computers. The energy required for cooling is significantly larger than that needed for the actual computation, which reverses energy usage patterns seen in conventional computing. At this point, however, one must not forget that quantum computers are usually not located "on-premise" and in an “isolated” location. Instead, they will be arranged in groups as part of high-performance computing centers that are highly specialized in operating such sophisticated computers. In such an environment, generating the required low operating temperatures is still a challenge but scales quite differently.
To assess whether this can be more sustainable, we must look at today’s alternatives to quantum computers and weigh the different drivers for resource efficiency.
Quantum computers vs. traditional supercomputers
Today’s supercomputing centers consume lots of space and, more importantly, consume lots of power. They are currently used for the most advanced calculations in science (e.g., in computational chemistry) or business (e.g., market simulations in finance). Because quantum computers will be able to solve problems much faster, they will replace less-efficient supercomputers and thus yield sustainability gains. The Finnish/Germany, quantum computer manufacturer IQM has already shown that by integrating their quantum computing systems into supercomputing environments, they could accelerate the computing capability of these supercomputers and thereby reduce overall power consumption.
5G/6G networks allow new designs
In the foreseeable future, the everyday business applications run in today’s data centers are unlikely to demand the power of a quantum computer. However, quantum computers might become a viable substitute if they will – sometime in the not-so-distant future – run these commercial applications in a more energy-efficient manner than today’s server farms. Let’s take a look into the future: Image what would be possible if we combine the low latency of 5G/6G networks with your “every day” quantum computer operated through the cloud. Due to their speed and superior energy efficiency, quantum computers will be preferred to classical computers. We are often led to believe that we will use quantum computers only for a relatively small subset of computing problems – and this is likely to be the case in the beginning – but once the superior energy-efficiency of quantum computers has been proven and 5G/6G networks are widely available, you could run your smartwatch on a quantum computer in the cloud. We can’t be sure whether there will ever be a “quantum first” principle for all computing classes. Still, it is possible, making it all the more interesting to think about the implications for a sustainable future.
With quantum towards net-zero
The development of commercially ready quantum computers for wide use is still ongoing. Therefore, we can only anticipate the final hardware architecture and how much energy will be needed to run it. But from everything we know, quantum computers are likely to outperform existing hardware, esp. today’s supercomputing centers, in terms of energy efficiency. However, more research is needed to reduce the energy required for cooling, to design quantum computing systems that run code in an energy-efficient manner, or to reduce the energy used for noise correction. But one thing is for sure: quantum computing is an essential building block toward net-zero!