Increasing the reach of quantum computing algorithms for chemistry applications using novel circuit reduction and Z2 symmetries-based methods

Abstract

Quantum computing hardware platforms have seen tremendous growth in terms of larger devices and improved error rates in the recent years. Even then, utilization of these devices for solving practical chemical problems remains challenging due to the cost of simulating electronic structure Hamiltonians on quantum computers being very high in terms of the required quantum resources like number of qubits, gate counts, circuit depths and number of measurements. In this talk, we will introduce new methods developed for exact and automated circuit reduction for circuits made from sequence of exponentials of Pauli operators. This family of quantum circuits is ubiquitous in quantum chemistry algorithms using quantum computers, for example, the Unitary Coupled Cluster ansatz, Qubit Coupled Cluster ansatz, Suzuki-Trotter decomposition for time evolution etc. This circuit reduction technique can be combined with methods using AI for determination of Pauli terms recently introduced in the literature. In addition, another technique for choosing an appropriate basis for the description of the chemical qubit Hamiltonian based on Z2 symmetry identification will be discussed and results showcasing reduction of required quantum resources will be presented.