The end result is a significantly reduced number of gates and much faster operation. This is important because errors in quantum hardware increase as a function of both time and number of operations.
The researchers then used this approach to study the chemical manganese.4○5Ca plays an important role in photosynthesis. Using this approach, they showed that they could calculate a so-called “spin ladder”, a list of the lowest energy states that an electron can occupy. This also defines the molecule’s spectrum, since the difference in energy between these states corresponds to the wavelength of light that they can absorb or emit.
Faster, but not fast enough
The system is not ready to run on today’s quantum computers because the error rate is still a bit too high. However, the operations required to run this type of algorithm can be performed very efficiently, so the error rate does not need to drop significantly before the system becomes runnable. The main determinant of whether an error occurs is how far down the time dimension you run the simulation, plus the number of measurements of the system you take in that time.
“This algorithm is particularly promising for short-term devices with favorable resource requirements, quantified by the number of snapshots (sample complexity) and maximum evolution time (coherence) required for accurate spectral calculation.” write the researchers.
However, the study also makes some major points. The first is that quantum computers are fundamentally different from other forms of computation that we have developed. These can perform operations similar to traditional algorithms, where operations are performed and results are determined. But they are also quantum systems that grow in complexity with each new generation of hardware, making them excellent for simulating other quantum systems. And there are many difficult problems related to quantum systems that we would like to solve.
In some ways, we may have just begun to scratch the surface of quantum computing’s potential. Until recently, there were many theories. It looks like we are now at the stage of using this for useful calculations. It means more people start thinking about smart ways to solve problems. In these cases, the hardware may be used in ways that the designers never thought possible.
Physical Physics, 2025. DOI: 10.1038/s41567-024-02738-z (About DOI).
