Imperfect Distributed Quantum Phase Estimation

Abstract

In the near-term, the number of qubits in quantum computers will be limited to a few hundreds. Therefore, problems are often too large and complex to be run on quantum devices. By distributing quantum algorithms over different devices, larger problem instances can be run. This distributing however, often requires operations between two qubits of different devices. Using shared entangled states and classical communication, these operations between different devices can still be performed. In the ideal case of perfect fidelity, distributed quantum computing is a solution to achieving scalable quantum computers with a larger number of qubits. In this work we consider the effects on the output fidelity of a quantum algorithm when using noisy shared entangled states. We consider the quantum phase estimation algorithm and present two distribution schemes for the algorithm. We give the resource requirements for both and show that using less noisy shared entangled states results in a higher overall fidelity.

Distributed Quantum Computing and Network Control for Accelerated VQE

“…Using the method of Yimsiriwattana et. al requires just 1 Bell pair to perform a non-local control gate and this Bell pair can also be used to perform multiple control gates when the control qubit is the same as is done in [28] for distributed quantum Fourier transform.…”

Quantum Algorithms and Simulation for Parallel and Distributed Quantum Computing

“…With the ability to generate equivalent non-local circuits, one can then start to consider quantum algorithms that can benefit from being distributed and parallelized. Such examples of distributed Shor's algorithm [4], Quantum Phase Estimation (QPE) [9], and α-VQE [5] have been considered.…”