Researchers have found a solution to a longstanding problem in quantum computing calculations, bringing us closer to the goal of advanced quantum chemical simulations.
The term, quantum computing, has been thrown around a lot in recent years. It is an emerging technology that uses quantum physics to perform computation, rather than classical physics.
Quantum computing have the potential to be substantially faster and perform calculations that classical computers simply cannot.
One such use of this extra computing power would be in chemical calculations. In chemistry, computational simulations of atoms act as the groundwork to many fields. They can be used to predict chemical mechanisms, better understand structures and develop sophisticated materials.
Configuration interaction (CI) is a method used in computational chemistry to calculate the energy of certain atomic systems. By knowing this, scientists can determine many physical properties of the system and shed light on how it behaves chemically.
This is done by investigating the relationship between the electrons orbiting each atom. Solving the ‘Schrodinger Equation’ by using the interactions of the electrons to determine the state of the system gives us this answer. On classical computers, however, the calculation time increases exponentially with the size of the system. Some calculations can take centuries to complete and are simply unfeasible.
Quantum computers, on the other hand, can solve the calculation on a much faster timescale.
Scientists from Osaka City University have just solved one of the hurdles to achieving large-scale quantum computing. This would allow us to investigate more complex systems and shed light on the fundamentals of some systems.
Authors Kenji Sugisaki and Takeji Takui say, “One of the most anticipated applications of quantum computers is electronic structure simulations of atoms and molecules”. The ability to perform these simulations would have exciting implications for many fields, including biology, mathematics and information science.
The issue is that current quantum computers don’t possess the information to process the calculations properly. They don’t have enough ‘quantum bits’ or ‘qubits’ to implement error calculations.
The error originates from the chemical system’s spin. Spin is a property that each chemical system has and is found by totalling the spin of each individual electron in any given system. Currently, spin values can be ‘contaminated’ by incorrect spin values. This is due to hardware issues, data incoherence and mathematical errors.
The calculations are time-dependent, which means an initially small error in spin can become extremely prominent and change the final result quite dramatically.
This acts as a barrier to large-scale quantum devices for chemical calculations.
Or it did, at least, but not anymore according to the paper published in September 2020. The team claim that they have found a way to implement an algorithm which allows them to select their desired spin quantum number – essentially fixing the errors caused by spin-contamination. This has never been achieved before and brings us one step closer to simulating quantum systems.
The researchers are now planning to implement algorithms designed for more complex electron systems and determine the state of them with high accuracy.