Researchers at Chalmers University of Technology, Sweden, have shown that they can solve a small part of a major logistics problem with their small quantum computer.
Interest in building quantum computers has gained considerable momentum in recent years. In 2019, Google’s research team made a breakthrough when its quantum computer managed to solve a task far more quickly than the world’s best supercomputer. The downside is that the solved task had no practical use whatsoever – it was chosen because it was judged to be easy to solve for a quantum computer, yet very difficult for a conventional computer. Therefore, an important task is now to find useful, relevant problems that are beyond the reach of ordinary computers, but which a relatively small quantum computer could solve.
Theoretical physicist Giulia Ferrini, one of the leaders of Chalmers University of Technology‘s quantum computer project which began in 2018, said: “We want to be sure that the quantum computer we are developing can help solve relevant problems early on. Therefore, we work in close collaboration with industrial companies.”
Quantum solutions to real problems
Together with Göran Johansson, Ferrini led the theoretical work when a team of researchers at Chalmers, including an industrial doctoral student from the aviation logistics company Jeppesen, recently showed that a quantum computer can solve an instance of a real problem in the aviation industry.
Assigning individual aircraft to different routes represents an optimisation problem, one that grows very rapidly in size and complexity as the number of routes and aircraft increases. Researchers hope that quantum computers will eventually be better at handling such problems than today’s computers.
Due to their different structure and function, quantum computers must be programmed in other ways than conventional computers. One proposed algorithm that is believed to be useful on early quantum computers is the so-called Quantum Approximate Optimisation Algorithm (QAOA).
The Chalmers research team has now successfully executed the QAOA on their quantum computer. The team demonstrated that it can successfully solve the problem of assigning aircraft to routes.
Jonas Bylander, senior researcher responsible for the experimental design, and one of the leaders of the project, said: “We have shown that we have the ability to map relevant problems onto our quantum processor. We still have a small number of qubits, but they work well. Our plan has been to first make everything work very well on a small scale, before scaling up.”
Surpassing today’s best computers would, however, require much larger devices. The researchers at Chalmers have now begun scaling up and are currently working with five quantum bits. The plan is to reach at least 20 qubits by 2021 while maintaining the high quality.