Qubit metrology for building a fault-tolerant quantum computer

TL;DR

This paper discusses the importance of precise qubit error measurement (metrology) as a critical step towards building scalable, fault-tolerant quantum computers capable of complex computations.

Contribution

It highlights the role of qubit error metrology as a key driver for improving qubit fidelity and enabling fault-tolerance in quantum computing architectures.

Findings

Error thresholds for fault-tolerance are around 10^{-18}.

Metrology of qubit errors is essential for technological progress.

Addressing physical and material challenges is crucial for error reduction.

Abstract

Recent progress in quantum information has led to the start of several large national and industrial efforts to build a quantum computer. Researchers are now working to overcome many scientific and technological challenges. The program's biggest obstacle, a potential showstopper for the entire effort, is the need for high-fidelity qubit operations in a scalable architecture. This challenge arises from the fundamental fragility of quantum information, which can only be overcome with quantum error correction. In a fault-tolerant quantum computer the qubits and their logic interactions must have errors below a threshold: scaling up with more and more qubits then brings the net error probability down to appropriate levels ~ $10^{-18}$ needed for running complex algorithms. Reducing error requires solving problems in physics, control, materials and fabrication, which differ for every implementation. I explain here the common key driver for continued improvement - the metrology of qubit errors.