(184c) Quantum Algorithms for Calculating Light-Absorption and Thermal Properties of Molecules and Materials

Quantum computers (if a sufficiently advanced one is ever built) will be able to simulate molecules and materials to a degree of accuracy impossible on today’s supercomputers. Although most efforts in quantum algorithm development have focused on the electronic structure problem, there are many properties that instead require accurate simulation of vibrational degrees of freedom. Such simulations of phonons or vibrations are necessary for studying light-absorption properties relevant to catalysis and photosynthesis, as well as thermal properties like heat transfer coefficients. In this talk, we introduce several algorithmic components relevant to quantum simulation of vibrational modes. Especially important is the choice of encoding, for which there are hardware-dependent resource trade-offs to consider. We present numerical results confirming that while the unary encoding requires more qubits than binary and Gray codes, the latter usually requires fewer operations. We introduce several subroutines—e.g. for the calculation of transition probabilities—which we prove are more efficient than previous approaches for early generations of quantum hardware. Additionally, we present numerical results that study the effect of hardware connectivity (topology of qubit layouts) on algorithm performance. Finally, we classify molecules and materials based on which are most likely to require a quantum computer in order to simulate accurately.