How to Build a Quantum Supercomputer

Evolution of Quantum Computing

• 💡 Early experiments in the 1980s explored if macroscopic variables obey quantum mechanics, inspired by concepts like Schrödinger's cat and observed in superconductors and crystal structures.
• 🚀 This foundational work led to complex quantum computation, culminating in Google's quantum supremacy experiment in 2019, demonstrating powerful calculations on 53 qubits.
• ⚠️ Despite early successes, the industry faces a "box canyon" in scaling beyond hundreds of qubits, with current methods making it difficult to reach millions of qubits efficiently.

Colab's Scaling Strategy

• 🎯 Colab aims for a fabrication leap by adopting advanced semiconductor industry technology to build higher-quality qubits and achieve massive scaling.
• 🛠️ Key fabrication methods include deposition and etch (replacing outdated liftoff technology), creating clean interfaces in-situ, and implementing wafer-scale integration.
• 🤝 The strategy involves collaboration with industry players like Applied Materials (for vacuum systems and processes) and Synopsis (for design software) to leverage existing expertise.

Wafer-Scale Integration Architecture

• 🧠 The proposed architecture uses wafer-scale integration across multiple layers: a qubit wafer (20,000 qubits), a wiring wafer (for thermal isolation and high-density connections), and a cryo-electronics wafer (for classical control circuits at 3 Kelvin).
• 🔌 This design allows for 100,000 wires on a single wafer, utilizing the low loss and thermal conductivity of superconductors, with thermal engineering to manage heat.
• 💡 A novel readout solution involves a microwave photon single photo multiplier to convert qubit states, enabling low-power, multiplexed readout and addressing a major scaling challenge.

Overcoming Technical & Business Challenges

• 💰 A critical focus is cost-effectiveness, aiming to reduce the price of quantum computers from tens of billions to hundreds of millions by leveraging mass production techniques.
• 🚧 Addressing cross-talk is essential, with solutions including ground planes, advanced physics models, and collaboration with design software companies.
• 📈 The long-term goal is to achieve 1-5 million qubits by 2033 through modular, reliable fabrication and assembly, emphasizing the need for mass production and reliability benchmarks.