While quantum computing holds the key to solving some of our most complex scientific challenges, current hardware is still limited by qubit counts and gate errors. Quantum error correction can overcome those errors, but it adds substantial overhead to every qubit and gate an algorithm uses. That makes circuit size one of the biggest factors in when a quantum algorithm becomes practical: every qubit and gate we remove lowers the bar that hardware must clear. To bring real-world quantum applications within reach sooner, it is critical to first compress the circuits that power them.
To help bridge this gap, the Google Quantum AI team is launching a competition on Kaggle challenging you to use AI to build smaller, more efficient quantum circuits. The competition is powered by kickmix, our new open source C++20 and Python library in Qualtran for efficiently building and testing large quantum circuits. Our companion paper, Leveraging verifiable structure in quantum circuits to find more efficient compilations with agentic AI, describes the approach in detail.
Turning compilation into an AI agent loop
In the past, optimizing quantum algorithms meant domain experts meticulously tuning circuits by hand and publishing incremental wins one paper at a time. Today, agentic AI can search for more efficient circuits automatically, but such results can only be trusted when candidate circuits can be efficiently verified for correctness. For arbitrary quantum circuits, classical verification is intractable because quantum gates create superpositions over exponentially many classical bitstrings. Fortunately, many of the most expensive subroutines in fault-tolerant algorithms can be built within a structured subclass of circuits, called “kickmix” circuits, which we introduced in our earlier work. Built from reversible classical logic, diagonal phase gates, and measurement-based uncomputation, kickmix circuits map each input bitstring to a single output bitstring and phase without creating new superpositions. A classical computer can therefore run randomized fuzz testing on bitstring inputs in linear time to establish the circuit’s approximate correctness on full quantum states with high confidence.
Randomized fuzz testing does not prove exact equivalence, but most quantum algorithms can tolerate a small, bounded error. In fact, using approximations can cut gate and qubit counts significantly. Finding such approximations by hand is tedious, making it a great task for AI agents. With kickmix in Qualtran, agents can build large circuits quickly and fuzz test them at 60 billion gates per second on a single CPU core.
How the competition works
The competition features three benchmarks, each targeting a major kickmix bottleneck in a useful quantum algorithm in order to call attention to the broad utility of this verification paradigm. For each benchmark, we provide a reference baseline circuit and a standalone verifier, both open source under the Apache 2.0 license. Your goal is to submit a circuit that passes the verifier while minimizing a cost score based on its qubit and gate counts:
- Fusion energy: Designing inertial confinement fusion targets requires simulating how quickly charged particles slow down in a hot, dense plasma fuel (Proceedings of the National Academy of Sciences (PNAS)). The main bottleneck is computing the electric potential energy between every pair of particles, which is inversely proportional to their distance. The task is a quantum take on the classic fast inverse square root: given the squared distance x, apply a phase proportional to 1/√x, accurate to a tiny fraction of its exact value.
- Optimization: Decoded Quantum Interferometry (Nature) is a quantum algorithm for solving hard combinatorial optimization problems. On one such problem, Optimal Polynomial Intersection (OPI), it finds better solutions than any known efficient classical algorithm. The main arithmetic bottleneck in solving OPI is decoding a Reed-Solomon code in superposition. The task is to build this decoder as a quantum circuit.
- Chemistry: Fertilizer production depends on nitrogen fixation, which converts nitrogen gas from the air into ammonia. Industry does this at high temperature and pressure, using about 1–2% of the world’s energy supply, while bacteria do it at ambient conditions with the enzyme nitrogenase, whose active site is an iron-molybdenum cluster called FeMoCo. Understanding how FeMoCo works requires modeling its strongly correlated electrons, a long-standing target for quantum computers. Our recent algorithm (Physical Review X (PRX)) makes that quantum simulation cheaper by classically factorizing the molecule’s Hamiltonian into a compact sum of squares, so the quantum computer needs far fewer steps. At each step, the main bottleneck is a quantum lookup table that loads the parameters of that factorized Hamiltonian in superposition. The task is to co-design both parts: find an accurate factorization that needs fewer steps, and build compact circuits to load its parameters so each step costs less.
Get involved
We have already seen the potential of AI-driven quantum research with Gemini 4 Argon, which is helping researchers at Google accelerate progress across both quantum error correction and algorithm design. We’re excited that the broader research community is embracing this approach too, with simultaneous independent work pairing the kickmix paradigm with AI agents to reduce costs on related subroutines. However, our own internal runs with Gemini models show that all three benchmarks can be further improved beyond the circuits reported to date (and we’ve published a hash of those circuits in our recent manuscript to reveal after the competition), so the competition remains open and interesting.
Could we get more out of a quantum computer simply by asking it to do less? We invite you to help us answer that question.
Visit the competition page on Kaggle to read the full details, explore the resources, and submit your work.
