Quantum Computers for Quantum Chemistry: Making the Best of a Limited Technology

Development of error correcting quantum computers for practical computations still lies out of reach. However, many algorithms have been designed for use with near-term quantum computers, commonly referred to as Noisy Intermediate-Scale Quantum (NISQ) devices. On such devices, there is a conflict between increasing computational power while maintaining a short quantum circuit depth. More circuits are needed to simulate more complex systems, but at the cost of a deeper quantum circuit which is often not achievable on NISQ devices. Therefore, a family of Variational Quantum Eigensolver (VQE) algorithms have been developed to offload much of the computational load onto a classical computer. These algorithms take advantage of the variational principle to optimize the wavefunction using optimization routines on a classical computer and obtaining the electronic energy of the wavefunction from a quantum computer. In this presentation, we introduce some of the most successful algorithms and discuss the limitations and how the field needs to grow.