Insider Brief
- Researchers from Alice & Bob and Inria have developed the most hardware-efficient method to date for preparing magic states, another potential step toward universal fault-tolerant quantum computing.
- Their “unfolded distillation” method reduces qubit requirements to just 53 per magic state—an 8.7× improvement over prior approaches—while also being five times faster using the company’s noise-biased cat qubits.
- This method fits seamlessly into Alice & Bob’s existing quantum error correction architecture, requiring no new components and reinforcing the long-term viability of their superconducting quantum platform.
- Image: From the recent paper: “Unfolded distillation: very low-cost magic state preparation for biased-noise qubits” (Ruiz et Al.)
PRESS RELEASE — Scientists from Alice & Bob,a global leader in the race for fault-tolerant quantum computing, and Inria, France’s national institute for research in digital science and technology, have submitted a new study for peer review illustrating the most hardware-efficient method to date for producing magic states on superconducting quantum computers, a critical step toward realizing practical quantum computation.
Preparing magic states has remained one of the most resource-intensive aspects of quantum computing. This work makes magic state preparation cheaper in terms of qubit requirements and considerably faster, consolidating the roadmap to the universal fault-tolerant gate set needed to run useful quantum applications at scale.
Their new approach, outlined in the paper “Unfolded distillation: very low-cost magic state preparation for biased-noise qubits” was recently posted on arXiv. The new code was inspired by existing methods and tailored to work with the company’s cat qubits, which inherently protect against bit flip errors in quantum computations (a ‘noise bias’).
To achieve universal quantum computation with the ability to run any possible quantum algorithm, including those with known speedups over classical ones like Shor’s and Grover’s algorithms, a quantum computer must support a complete set of specific fundamental operations or gates. While some gates can be directly implemented, others require the use of special quantum resources known as magic states. These states must be carefully prepared and manipulated during computation to enable “non-trivial” operations that cannot otherwise be executed directly, completing the universal gate set. In other words, magic states enable the last gates required to complete the set of operations needed to perform any possible quantum algorithm.
The State of Magic State Research
Optimal magic state distillation would require complex 3D arrangements of qubits leading to architectures too hard to engineer in solid state QPUs. Recent research from Google scientists, theorized that magic state production with low error rates would require just 463 qubits in a novel 2D architecture, combining decades of quantum error correction research and overcoming the 3D architecture challenge to significantly reduce the qubit needs.
The researchers at Alice & Bob and Inria have managed to “unfold” the 3D code, much like flattening a box, into an even more practical 2D layout. This unfolded code for magic state preparation, internally nicknamed the “Heart Code” for its distinctive shape, is only possible thanks to noise-biased qubits, such as the cat qubits developed by Alice & Bob.
Fig. 5 from the recent paper: “Unfolded distillation: very low-cost magic state preparation for biased-noise qubits” Ruiz et Al.
The unfolded code simplifies overall operations and reduces overhead, requiring only 53 qubits to produce one magic state. The result is a remarkable 8.7× reduction in qubit requirements compared to the leading approaches while requiring 5× fewer quantum error correction cycles, making it approximately 5× faster than state-of-the-art superconducting platforms for the same error rate of less than 1 in a million.
“The most advanced players in quantum have lined up breakthrough after breakthrough to reduce the costs of magic state preparation, and it’s exciting to see how our work further improves the state of the art on noise-biased qubits.” said Diego Ruiz, author of the paper and a Ph.D. student at Alice & Bob and Inria.
Importantly, this magic state protocol only uses components that are already required for Alice & Bob’s quantum error correction architecture, including both the fundamental operations and the physical cat qubits. Hence, no new developments are needed, and the company can focus on reaching the targeted performance.
This research highlights the promising advantages of cat qubits’ noise bias to reduce the hardware overhead needed for useful quantum computing, not only when combined with advanced error codes like LDPC outlined in another recent paper by Alice & Bob researchers, but now also in the context of magic state preparation.
“This looming obstacle to useful quantum computers is finally being solved by the community, with some players even achieving the first proof-of-concept magic state preparation in experimental settings,” said Théau Peronnin, CEO of Alice & Bob. “Capitalizing on the cat qubits, this work further de-risks our roadmap while showcasing the long-term advantages of our universal platform.”
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