Alice & Bob’s Cat Qubit Work Published in Nature

Insider Brief

• Alice & Bob announce the publication of its seminal research in Nature, showcasing the company’s advances in cat qubit technology.
• The researchers report extending the bit’s turnaround time from milliseconds to tens of seconds, thousands of times better than any other type of superconducting qubit.
• The researchers used the Alice & Bobs Boson 3 chipset for this result.

PRESS RELEASE – Alice & Bob, a global leader in the race for fault-tolerant quantum computing, today announces the publication of its fundamental research in Nature, featuring significant advances in cat qubit technology. This study, Quantum control of a cat-qubit with bit rotation times exceeding ten secondscarried out in collaboration with the QUANTIC team (Mines Paris – PSL, Ecole Normale Suprieure and INRIA), demonstrates an unprecedented improvement in the stability of superconducting qubits, marking a critical milestone towards useful fault-tolerant quantum computing.

Researchers have dramatically extended bit reversal times from milliseconds to tens of seconds, thousands of times better than any other type of superconducting qubit.

Quantum computers face two types of errors: bit-flips and phase-flips. Cat’s qubits exponentially reduce bit flips, which are analogous to classical bit flips in digital computing. As a result, remaining phase shifts can be more efficiently addressed with simpler error correction codes.

“This successful collaboration leveraged our cat cube design to achieve very long bit rotation times while maintaining quantum control, said Raphal Lescanne, CTO of Alice & Bob. Although the journey is still unfolding, we remain committed to efficiently addressing the challenges of quantum error correction.”

The researchers used the Alice & Bobs Boson 3 chipset for this record-breaking result, which features a cat qubit design called TomCat. TomCat uses an efficient quantum tomography (measurement) protocol that allows control of quantum states without the use of a transmon, a common circuit used by many quantum companies, but one of the main sources of bit-flips for cat qubits. This design also minimizes the qubit’s on-chip footprint by removing drive lines, cables, instrumentation, making this stable and scalable qubit.

Recently, Alice & Bob made publicly available their new Boson 4 chip that achieves over 7 minutes of bit-flip lifetime. Therefore, the results from this Nature Publication can be reproduced by users in Boson 4 on Google Cloud.

Although Boson’s latest Alice & Bobs chips are getting closer to the company’s goals for bit-flipping protection, Alice & Bob plans to further advance their technology. Future iterations will focus on increasing the cat qubit phase turnaround time and readout fidelity to meet the requirements of their latest architecture to deliver a 100 qubit logic quantum computer.

Key advances highlighted in the research include:

• Enhanced Quantum Control: The team demonstrated phase control of coherent overlaps by achieving macroscopic bit turnaround times, a necessary step to scale these dynamic qubits to fully shielded hardware-efficient architectures.
• Significant reduction of quantum errors: By utilizing a system that essentially stabilizes against bit reversals, only phase reversals remain as the significant source of error, which can be corrected more efficiently. Instead of using a two-dimensional code to correct both types of errors, a more efficient one-dimensional code addresses phase reversals.

Alice & Bob is committed to further expanding the stability of cat qubits and improving quantum error correction methods, said Th.au Peronnin, CEO of Alice & Bob. This research, reported by Nature, highlights the possibility of long spin times for the bits unmatched by other superconducting qubits.