Google Unveils Willow: A 105-Qubit Superconducting Chip with Enhanced Error Correction and Quantum Supremacy

Yesterday, I landed in Santa Clara for the Q2B (Quantum 2 Business) conference, where I’ll be speaking on "Quantum Algorithms in 2024: How Should We Feel?" and closing the event with an Ask-Us-Anything session alongside John Preskill. If you’re attending, feel free to drop by and say hi!

Coinciding with Q2B, Google’s Quantum AI team officially announced their latest achievement: Willow, a new 105-qubit superconducting chip. This announcement is significant for several reasons:

• Error-Corrected Surface Code Qubit: For the first time, Google has demonstrated an error-corrected surface code qubit using this chip.
• Larger Quantum Supremacy Experiment: They’ve also conducted a new, larger quantum supremacy experiment based on Random Circuit Sampling (RCS).

Technical Details and Milestones

Google's Willow is a major step forward in the field of quantum computing. Here’s a breakdown of what’s changed and why it matters:

• Qubit Count: Willow features 105 qubits, nearly doubling the number from their previous chip.
• Coherence Time: The coherence time for these qubits has improved by a factor of 5 compared to Google's 2019 chip. This means the qubits can maintain their quantum state longer, which is crucial for running more complex algorithms.
• Gate Fidelity:
  • For controlled-Z gates: ~99.7%
  • For "iswap" gates: ~99.85%

These improvements in coherence time and gate fidelity are significant because they directly impact the reliability and performance of quantum circuits.

Demonstrations and Benchmarks

Google used Willow to perform several impressive demonstrations:

• Error-Corrected Surface Code Qubit: This is a key milestone in error correction, which is essential for building reliable quantum computers. By demonstrating an error-corrected qubit, Google has shown that they can protect quantum information from decoherence.
• Quantum Supremacy with RCS: They conducted a larger Random Circuit Sampling experiment, further solidifying their claim of quantum supremacy. This experiment involves running random circuits and comparing the results to classical simulations, which are infeasible for large enough circuits.

Industry Reactions

The announcement has garnered significant attention:

• Sundar Pichai, Google’s CEO, tweeted about Willow, highlighting its importance.
• Elon Musk replied with a simple but telling "Wow," indicating the broader tech community's interest and excitement.

Community Feedback

Yesterday, I saw numerous comments on Twitter, Hacker News, and other platforms asking for my take on the announcement. For those who have been following quantum computing closely over the past few years, this news is not entirely surprising. Since Google’s original quantum supremacy milestone in 2019, they’ve consistently improved their qubits' quality and quantity.

However, seeing these advancements come to fruition is still incredibly gratifying. It’s a clear sign that we are making steady progress toward practical quantum computing.

Conclusion

Google's Willow represents a significant leap forward in the field of quantum computing. With its enhanced error correction capabilities and increased qubit count, it paves the way for more complex and reliable quantum algorithms. As we move into 2024, these developments will likely continue to shape the landscape of quantum technology.