부산대학교 도서관

Quantum computers today are noisy and limited in the number of qubits that can be set with reasonable fidelities and gate times for each system. Since the current limit on the number of qubits is difficult to surpass, it is expected that the future of quantum computing will lie in connecting different quantum computers together to form a quantum network, each with its own limitations. Herein lies the field of distributed quantum computing optimized for large-scale communication. One such system that has been designed is the Quantum Message Passing Interface (QMPI). This interface, unlike the classical MPI, takes advantage of quantum teleportation to communicate between different quantum nodes but leverages the framework built for classical MPI. This general interface is essential as we try to connect various quantum computers, as it can be used to develop distributed quantum algorithms across various nodes. In this work, we develop a reference implementation for a QMPI interface in Qiskit and characterize its performance. In our interface, we have implemented point-to-point and optimized collective operations for larger distributed quantum networks. To test our framework, we demonstrate our implementation with applications that can leverage the QMPI framework including Trotterization of the transverse field Ising model and distributive quantum phase estimation. Lastly, we have developed a new technique for decomposing quantum gates across many nodes which leverages multi-controlled Toffolli gates. This technique beats the state of the art for an adder circuit in terms of fidelity and the number of EPR pairs used.