Simulating Quantum State Transfer between Distributed Devices using Noisy Interconnects

TL;DR

This paper introduces a practical quasiprobability decomposition method for simulating high-fidelity quantum state transfer over noisy interconnects, reducing sampling overhead and improving effective fidelity in distributed quantum computing.

Contribution

It presents a generalized, tunable QPD approach for realistic noisy interconnects, with experimental validation demonstrating reduced overhead and enhanced transfer fidelity.

Findings

Effective state transfer fidelity exceeds direct noisy transfer

Reduced sampling overhead with the new QPD method

Feasible implementation on current quantum devices

Abstract

Scaling beyond individual quantum devices via distributed quantum computing relies critically on high-fidelity quantum state transfers between devices, yet the quantum interconnects needed for this are currently unavailable or expected to be significantly noisy. These limitations can be bypassed by simulating ideal state transfer using quasiprobability decompositions (QPDs). Wire cutting, for instance, allows this even without quantum interconnects. Nevertheless, QPD methods face drawbacks, requiring sampling from multiple circuit variants and incurring substantial sampling overhead. While prior theoretical work showed that incorporating noisy interconnects within QPD protocols could reduce sampling overhead relative to interconnect quality, a practical implementation for realistic conditions was lacking. Addressing this gap, this work presents a generalized and practical QPD for state transfer simulation using noisy interconnects to reduce sampling overhead. The QPD incorporates a single tunable parameter for straightforward calibration to any utilized interconnect. To lower practical costs, the work also explores reducing the number of distinct circuit variants required by the QPD. Experimental validation on contemporary quantum devices confirms the proposed QPD's practical feasibility and expected sampling overhead reduction under realistic noise. Notably, the results show higher effective state transfer fidelity than direct transfer over the underlying noisy interconnect.