Alice & Bob, a quantum computing firm with offices in Paris and Boston, has demonstrated significant advances in the resilience of its “cat qubits” against bit-flip errors, a major obstacle in the development of stable quantum computers. According to a company announcement made on September 25, 2025, researchers achieved bit-flip times exceeding one hour – a considerable improvement over the previously recorded 430 seconds (approximately seven minutes) attained in 2024 on their Boson 4 chip. This achievement is particularly noteworthy as it surpasses the 13-minute threshold required for the company’s early fault-tolerant quantum computer (eFTQC) roadmap, slated for 2030, which aims to deliver a device with 100 logical qubits.
The extended cat qubit stability was achieved using the company’s latest qubit design, the Galvanic Cat, which employs the same architecture as their 12-cat qubit Helium 2 chip. Raphael Lescanne, CTO and Co-Founder of Alice & Bob, stated that the progress stems from a year of improvements encompassing software, experimental techniques, and advanced engineering. At a mean photon number of 11, the team measured bit-flip times ranging from 33 to 60 minutes with 95% confidence. Furthermore, they successfully performed a Z gate operation on the cat qubit with 94.2% fidelity in 26.5 nanoseconds, a crucial step towards implementing effective error correction protocols.
The significance of this advancement lies in its potential to reduce the hardware requirements for large-scale quantum computers dramatically. By virtually eliminating bit-flip errors – one of the two primary error types affecting quantum computations – Alice & Bob’s cat qubits enable the use of more efficient error-correcting codes. The company estimates that this could reduce the hardware needed by up to 200 times, a substantial reduction compared to other quantum computing approaches. Interestingly, the observed bit-flip times now exceed typical timescales for cosmic ray impacts, suggesting a degree of insensitivity to such external disturbances. For context, other leading superconducting qubits currently achieve bit-flip times of approximately 0.025 seconds (25 milliseconds), millions of times shorter than the latest result from Alice & Bob. The next step, as outlined by the company, is to evaluate the performance of this enhanced bit-flip resilience under two-qubit gate operations (Controlled NOT).
Alice & Bob’s 2030 Roadmap and Bit-Flip Time Targets
Alice & Bob’s 2030 Roadmap and Bit-Flip Time Targets Alice & Bob’s ambitious 2030 roadmap, targeting an early fault-tolerant quantum computer (eFTQC) with 100 logical qubits for initial applications in materials science, receives substantial reinforcement from recent advances in cat qubit stability. As announced on September 25, 2025, researchers at the Paris and Boston-based quantum computing firm have demonstrated bit-flip times exceeding one hour – a critical milestone in achieving fault tolerance. This achievement not only surpasses the company’s internal 2030 target of 13 minutes for sustained bit-flip protection, but also represents a considerable leap beyond their previous record of 430 seconds (approximately seven minutes) attained in 2024 on the Boson 4 chip.
The extended coherence was achieved utilising Alice & Bob’s latest qubit design, the Galvanic Cat, which also underpins their 12-cat qubit Helium 2 chip. A year of focused improvements across software, experimental techniques, and advanced engineering facilitated the breakthrough. Specifically, the team measured bit-flip times ranging from 33 to 60 minutes at a 95% confidence interval, utilising a mean photon number of 11. This level of stability is particularly noteworthy as it now exceeds the typical timescales associated with cosmic ray impacts, suggesting a degree of inherent resilience to external disturbances. For comparative context, other leading superconducting qubits currently exhibit bit-flip times of approximately 0.025 seconds (25 milliseconds) – millions of times shorter than the latest result from Alice & Bob.
The significance of these extended bit-flip times extends beyond simply meeting a roadmap target. By effectively mitigating one of the two primary error types affecting quantum computations – bit-flip errors – Alice & Bob’s cat qubit technology enables the implementation of more efficient error-correcting codes. This, in turn, has the potential to reduce the hardware overhead required for large-scale quantum computers dramatically. The company estimates that this approach could reduce the necessary hardware by up to 200 times, a substantial reduction compared to alternative quantum computing architectures. Furthermore, the team demonstrated the ability to perform a Z gate operation on the cat qubit with 94.2% fidelity in 26.5 nanoseconds, a crucial step towards realising practical error correction protocols. The next planned step, according to Raphael Lescanne, CTO and Co-Founder of Alice & Bob, is to evaluate the performance of this enhanced bit-flip resilience under two-qubit gate operations – specifically, the Controlled NOT gate.
Alice & Bob’s Cat Qubit Performance with Z Gate Operations
The extended coherence was demonstrated using Alice & Bob’s latest qubit design, the Galvanic Cat, which also forms the basis of their 12-cat qubit Helium 2 chip. Researchers, leveraging a year of improvements across software, experimental techniques, and advanced engineering, measured bit-flip times ranging from 33 to 60 minutes at a 95% confidence interval, utilising a mean photon number of 11. This level of stability is noteworthy as it now exceeds the typical timescales associated with cosmic ray impacts, suggesting a degree of inherent resilience to external disturbances. To provide context, other leading superconducting qubits currently exhibit bit-flip times of approximately 0.025 seconds (25 milliseconds), which is millions of times shorter than the latest result from Alice & Bob.
Beyond simply extending coherence times, Alice & Bob demonstrated the ability to perform quantum operations on the cat qubit while maintaining this stability. Specifically, the team successfully executed a Z gate operation with 94.2% fidelity in 26.5 nanoseconds. While the impact of the drive used to perform the Z gate on bit-flip incidence was not directly measured in this experiment, previous data suggests it remains minimal. This operational fidelity is a crucial step towards realising practical error correction protocols. By virtually eliminating one of the two primary error types – bit-flip errors – Alice & Bob’s cat qubit technology enables the implementation of more efficient error-correcting codes, potentially reducing the hardware requirements for large-scale quantum computers by up to 200 times. Raphael Lescanne, CTO and Co-Founder of Alice & Bob, stated that the next step will be to evaluate the performance of this enhanced bit-flip resilience under two-qubit gate operations, specifically the Controlled-NOT gate.
Alice & Bob’s Error Correction Efficiency with Cat Qubits
Beyond simply extending coherence times, Alice & Bob demonstrated the ability to perform quantum operations on the cat qubit while maintaining this stability. Specifically, the team successfully executed a Z gate operation with 94.2% fidelity in 26.5 nanoseconds. While the impact of the drive used to perform the Z gate on bit-flip incidence was not directly measured in this experiment, previous data suggests it remains minimal. This operational fidelity is a crucial step towards realising practical error correction protocols. By virtually eliminating one of the two primary error types – bit-flip errors – Alice & Bob’s cat qubit technology enables the implementation of more efficient error-correcting codes, potentially reducing the hardware requirements for large-scale quantum computers by up to 200 times. Raphael Lescanne, CTO and Co-Founder of Alice & Bob, indicated that the next step will be to evaluate the performance of this enhanced bit-flip resilience under two-qubit gate operations, specifically the Controlled NOT gate.
Alice & Bob’s Cat Qubit Technology and Competitive Advantage
The achievement stems from improvements to Alice & Bob’s latest qubit design, the Galvanic Cat, which also underpins their 12-cat qubit Helium 2 chip. Researchers, building upon a year of iterative enhancements that encompassed software optimisation, refined experimental techniques, and advanced engineering, measured bit-flip times ranging from 33 to 60 minutes with a 95% confidence interval, utilising a mean photon number of 11. This level of stability is noteworthy not only for exceeding the company’s internal targets but also for demonstrating a degree of insensitivity to external disturbances, as the measured bit-flip time now surpasses typical timescales for cosmic ray impacts. For comparative context, other leading superconducting qubits currently achieve bit-flip times of approximately 0.025 seconds (25 milliseconds) – a difference of millions of times slower than the latest result from Alice & Bob.
Beyond simply extending coherence, Alice & Bob demonstrated the ability to perform quantum operations on the cat qubit while maintaining this enhanced stability. The team successfully executed a Z gate operation with 94.2% fidelity in 26.5 nanoseconds. While the impact of the drive used to perform the Z gate on bit-flip incidence was not directly measured in this experiment, existing data suggests it remains minimal. This operational fidelity is a crucial step towards developing practical error correction protocols, as the virtual elimination of bit-flip errors – one of the two primary error types affecting quantum computers – enables the implementation of more efficient error-correcting codes. According to the company, this could potentially reduce the hardware requirements for large-scale quantum computers by up to 200 times. Raphael Lescanne, CTO and Co-Founder of Alice & Bob, indicated that the next phase of research will focus on evaluating the performance of this enhanced bit-flip resilience under two-qubit gate operations, specifically the Controlled NOT gate.
