Thermal properties of nanomaterials are crucial to not only improving our fundamental understanding of condensed matter systems, but also to developing novel materials for applications spanning research and industry alike. Since quantum effects arise
at the nanomaterial scale, these systems are difficult to simulate on classical computers. Quantum computers, by contrast, can efficiently simulate quantum many-body systems. However, current algorithms for calculating thermal properties of these systems incur significant computational costs in that they either prepare the full thermal (i.e., mixed) state on the quantum computer, or else they must sample a number of pure states from a distribution that grows with system size. Canonical thermal pure quantum states provide a promising path to estimating thermal properties of quantum materials as they neither require preparation of the full thermal state nor require a large number of samples. Remarkably, fewer samples are required as the system size grows. Here, we present a method for preparing canonical TPQ states on quantum computers and demonstrate its efficacy in estimating thermal properties of quantum materials. Due to its increasing accuracy with system size, as well as its flexibility in implementation, we anticipate that this method will enable finite temperature explorations of relevant quantum materials on near-term quantum computers.
ArQTiC is an open-source, full-stack software package built for the simulations of materials on quantum computers. It currently can simulate materials that can be modeled by any Hamiltonian derived from a generic, one-dimensional, time-dependent Heis
enberg Hamiltonain. ArQTiC includes modules for generating quantum programs for real- and imaginary-time evolution, quantum circuit optimization, connection to various quantum backends via the cloud, and post-processing of quantum results. By enabling users to seamlessly perform and analyze materials simulations on quantum computers by simply providing a minimal input text file, ArQTiC opens this field to a broader community of scientists from a wider range of scientific domains.
