A small and interesting architecture for early fault-tolerant quantum computers

TL;DR

This paper proposes a minimalistic, fault-tolerant quantum computing architecture utilizing small color codes, enabling universal gates through teleportation and providing protocols for hardware testing.

Contribution

It introduces a novel architecture based on small color codes for early fault-tolerant quantum computing with a focus on teleportation-based gate implementation.

Findings

Uses [[4, 2, 2]] and [[8, 3, 2]] color codes for logical gates

Optimizes by minimizing quantum teleportation operations

Provides an experimental protocol for testing the architecture

Abstract

We present an architecture for early fault-tolerant quantum computers based on the smallest interesting colour code (Earl Campbell, 2016). It realizes a universal logical gate set consisting of single-qubit measurements and preparations in the X and Z bases, single-qubit Hadamard (H) gates, and three-qubit controlled-controlled-Z (CCZ) gates. State teleportations between [[4, 2, 2]] (2D) and [[8, 3, 2]] (3D) error-detecting color codes allow one to make use of the respective transversal H and CCZ gates that these codes possess. As such, minimizing the number of logical quantum teleportation operations, not the number of logical quantum non-Clifford gates, is the relevant optimization goal. To help hardware developers characterize this architecture, we also provide an experimental protocol tailored to testing logical quantum circuits expressed in it.