Restructure: USD fix + updated descendants

# [TECH] Quantum Computing Hardware

**Quantum Computing Hardware** implements quantum bits (qubits) in physical systems — superconducting circuits, trapped ions, photons, neutral atoms — with sufficient coherence and fidelity to run quantum algorithms.

## Overview

The leading platforms: **superconducting qubits** (IBM, Google) — fast gates, chip-based, currently 100–1000 physical qubits; **trapped ions** (IonQ, Quantinuum) — high fidelity (>99.9%), all-to-all connectivity; **neutral atoms** (QuEra) — reconfigurable arrays, 1000+ qubits demonstrated; **photonic** (Xanadu, PsiQuantum). Google's Sycamore (2019) claimed quantum supremacy for a specific sampling task. IBM's Condor (2023, 1121 qubits) and Heron processors pursue fault tolerance. Fault-tolerant quantum computing (requiring ~1M physical qubits per logical qubit for surface code) is estimated 10–20 years away.

## Key Actors

- **Companies**: IBM (Quantum, 2016), Google Quantum AI (2012), IonQ (2015), Quantinuum (2021), QuEra (2018), Xanadu (2016), Rigetti (2013)
- **Investors**: \$USD 35B+ invested in quantum computing globally (2015–2023, McKinsey)

## Key Patents

IBM, Google, and IonQ hold the largest quantum computing patent portfolios (thousands of patents across qubit design, control electronics, error correction).

## Economic Value

Current market: **\$USD 1.3 billion/year** (2023, IDC). McKinsey projects \$USD 170B–\$USD 450B by 2035 from pharmaceutical, chemical, financial, and logistics applications.

## Notes

McKinsey *Quantum Technology Monitor* 2023. IDC *Quantum Computing Market Forecast* 2023. The technology is pre-commercial in most applications; economic projections are highly uncertain.

## What This Enables

This is a current frontier node in this graph — no downstream connections yet recorded in this graph.

# Parents

* [SCI] BCS Superconductivity
* [SCI] BCS Superconductivity
* [SCI] Quantum Optics
* [SCI] Condensed Matter & Topological Physics
* [TECH] Optical Fiber Communications
* [SCI] Quantum Computing Theory
* [SCI] Cryogenics