# Extracting Success from IBM's 20-Qubit Machines Using Error-Aware Compilation

## TL;DR

This paper presents an error-aware compilation method for IBM's 20-qubit quantum computers that improves success probability and reduces error, using a fidelity-based metric and beam search heuristic.

## Contribution

It introduces a novel compilation approach that accounts for qubit error rates and employs a beam search heuristic to optimize circuit placement on NISQ devices.

## Key findings

- Increased estimated success probability of quantum circuits.
- Reduced KL-divergence indicating closer approximation to ideal distributions.
- Effective error-aware compilation on real IBM quantum hardware.

## Abstract

NISQ (Noisy, Intermediate-Scale Quantum) computing requires error mitigation to achieve meaningful computation. Our compilation tool development focuses on the fact that the error rates of individual qubits are not equal, with a goal of maximizing the success probability of real-world subroutines such as an adder circuit. We begin by establishing a metric for choosing among possible paths and circuit alternatives for executing gates between variables placed far apart within the processor, and test our approach on two IBM 20-qubit systems named Tokyo and Poughkeepsie. We find that a single-number metric describing the fidelity of individual gates is a useful but imperfect guide. Our compiler uses this subsystem and maps complete circuits onto the machine using a beam search-based heuristic that will scale as processor and program sizes grow. To evaluate the whole compilation process, we compiled and executed adder circuits, then calculated the KL-divergence (a measure of the distance between two probability distributions). For a circuit within the capabilities of the hardware, our compilation increases estimated success probability and reduces KL-divergence relative to an error-oblivious placement.