Faster Quantum-Chemistry Algorithms by Hardware-Tailored Circuits

The variational quantum eigensolver (VQE) is a promising tool to enable molecular-energy estimation on near-term quantum hardware. However, implementations of VQE circuits for the interesting set of medium-sized molecules have been impaired by decoherence. Current VQE circuits have too many gates and thus take too long to execute. In this work, we reduce the execution time of common VQE building blocks: the qubit excitation elements. We do so by compiling qubit excitation elements into short circuits of efficient and hardware-tailored gates. We build these gates from Heisenberg-exchange interactions in semiconducting qubits, and from transverse couplings in superconducting qubits. Our qubit excitation elements reduce the execution time of VQE circuits by about 40% and 60% in semiconducting and superconducting platforms, respectively.