Google's quantum mic drop: Willow chip ends 30-year challenge

Tech giant Googlehas launched Willow, a quantum computing chip that is touted as a breakthrough that can reduce errors exponentially.

“Introducing Willow, our new state-of-the-art quantum computing chip with a breakthrough that can reduce errors exponentially as we scale up using more qubits, cracking a 30-year challenge in the field,” Sundar Pichai, Chief Executive Officer of Alphabet and Google, said in a post on X.

Qubits are the building blocks of quantum computers, just like bits are for regular computers.

Quantum computers have a big problem: errors. Qubits, the special parts that make quantum computers work, are easily disturbed by their surroundings. This means they lose information quickly, making it hard to do complex calculations. The more qubits one adds, the worse the problem can get, and the quantum computer can start to act like a regular one.

Imagine building a tower with blocks. The more blocks one adds, the taller it gets, but it is also more likely to topple over. In the world of quantum computers, this is the problem of 'scaling up’. As one adds more parts (qubits), errors become more likely.

According to Google, the new quantum chip solves this problem.

“Today in Nature, we published results showing that the more qubits we use in Willow, the more we reduce errors, and the more quantum the system becomes. We tested ever-larger arrays of physical qubits, scaling up from a grid of 3x3 encoded qubits, to a grid of 5x5, to a grid of 7x7 — and each time, using our latest advances in quantum error correction, we were able to cut the error rate in half,” Hartmut Neven, Founder and Lead, Google Quantum AI, noted in a blog post.

This breakthrough, known as ‘below threshold,’ marks a significant milestone in quantum computing by demonstrating the ability to reduce errors while scaling up the number of qubits, explained Neven, adding that error correction has been a major hurdle since the concept of quantum error correction was first proposed by American computer scientist Peter Shor in 1995.

Quantum error correction is like a special code that protects the delicate information stored in quantum computers from getting scrambled.

What’s interesting is that Willow completed a standard benchmark computation in under five minutes, a task that would take even the fastest supercomputers today an incomprehensibly long 10 septillion years or 10,000,000,000,000,000,000,000,000 years.

“This mind-boggling number exceeds known timescales in physics and vastly exceeds the age of the universe,” remarked Neven.

“It’s a strong sign that useful, very large quantum computers can indeed be built. Willow brings us closer to running practical, commercially-relevant algorithms that can’t be replicated on conventional computers,” he added.

Willow, a quantum processor with 105 qubits, was manufactured at Google’s fabrication facility in Santa Barbara.

Significance of quantum computers

Several companies are developing quantum computers with varying qubit counts. IBM leads with over 1,000 qubits in its Condor processor, while Rigetti and IonQ have systems with tens of qubits. D-Wave specialises in quantum annealers with over 5,000 qubits, though its architecture differs.

However, qubit count alone doesn’t determine a quantum computer’s power; factors such as qubit quality, connectivity, and overall system design are equally crucial.

Quantum computing harnesses the principles of quantum mechanics to perform calculations that are beyond the reach of even the most powerful classical computers. This emerging field has the potential to revolutionise various sectors, including medicine discovery, materials science, finance, and artificial intelligence. 

In medicine discovery, quantum computers can accelerate the process of identifying and designing new medications by simulating molecular interactions with unprecedented accuracy. In materials science, they can help discover novel materials with superior properties for applications in energy, electronics, and other fields.

In the world of finance, quantum computers can optimise trading strategies, improve risk assessment, and develop more sophisticated financial models. In AI, quantum computing can enhance machine learning algorithms, enabling faster and more accurate data analysis and pattern recognition. 

“We see Willow as an important step in our journey to build a useful quantum computer with practical applications in areas like drug discovery, fusion energy, battery design + more,” explained Pichai.

According to Neven, the next crucial step is to use current quantum chips to perform a "useful, beyond-classical" computation that has real-world applications, and the company believes the Willow generation of chips will play a key role in achieving this.