Variational Quantum Eigensolvers in the Era of Distributed Quantum Computers

Abstract: The computational power of a quantum computer is limited by the number of qubits available for information processing. Increasing this number within a single device is difficult; it is widely accepted that distributed modular architectures are the solution to large scale quantum computing. The major challenge in implementing such architectures is the need to exchange quantum information between modules. In this work, we show that a distributed quantum computing architecture with {\it limited} capacity to exchange information between modules can accurately solve quantum computational problems. Using the example of a variational quantum eignesolver with an ansatz designed for a two-module (dual-core) architecture, we show that three inter-module operations provide a significant advantage over no inter-module (or serially executed) operations. These results provide a strong indication that near-term {\it modular} quantum processors can be an effective alternative to their monolithic counterparts.