Top quantum computers by logical qubit
Yesterday, we looked at the physical gate-based qubit leaderboard. Today, as promised we are pivoting to look into the largest logical qubit based systems.
Yesterday, we looked at the physical gate-based qubit leaderboard that I have been tracking for the last few months [1]. Today, as promised we are pivoting to look into the largest logical qubit based systems. This updated view reframes what it means to be the “largest” quantum computer. I’m still more interested in who will run Shor’s algorithm and demonstrate outputs from that as a pure criteria for what I’m trying to track. To that end, counting physical qubits has always offered a clear and simple benchmark, but it hides the enormous gap between raw qubit count and usable computational capacity. Logical qubits represent progress toward true fault-tolerance or at least that is what they seem to be indicating. It’s the ability to perform long, stable computations without cascading errors that will help deliver production usability.
In that sense, this new leaderboard highlights depth over breadth. A system with only a few dozen logical qubits may outperform one with thousands of physical qubits if those logical units are genuinely error-corrected and capable of sustained operation. As the field matures, the trajectory of meaningful progress will likely be defined not by scale alone, but by how much reliable computation can be achieved per logical qubit.
Top logical-qubit quantum computers (as of November 7, 2025):
Quantinuum Helios – 48 logical qubits fully error-corrected (November 5, 2025) United Kingdom / United States
Harvard / MIT / QuEra – 48 logical qubits error-corrected operations (December 6, 2023) United States
Atom Computing / Microsoft – 28 logical qubits neutral-atom logical circuit (November 19, 2024) United States
Microsoft & Quantinuum – 12 logical qubits fault-tolerant hybrid demo (September 10, 2024) United States
IBM qLDPC Gross Code – 12 logical qubits in logical memory (April 17, 2024) United States
It is pretty straightforward to get to that top 5 logical-qubit quantum computers list, but other entries could be delivering something soon including Google Willow (United States), Pasqal (France), Rigetti (United States), Alpine Quantum Technologies (Austria), and IonQ (United States). I could see a lot of press releases and other research efforts related to delivering logical qubits, but none of them delivered a number that would rank them in the top 5 systems. Let’s rewind back to my previous list for a moment and just compare the huge gap between physical and logical qubit counts.
Top 10 quantum computers by universal gate-based physical qubits:
Atom Computing - 1,180 qubits (October 24, 2023) United States
IBM Condor - 1,121 qubits (December 4, 2023) United States
CAS Xiaohong - 504 qubits (December 6, 2024) China
IBM Osprey - 433 qubits (November 9, 2022) United States
Fujitsu & RIKEN - 256 qubits (April 22, 2025) Japan
Xanadu Borealis - 216 qubits (June 1, 2022) Canada
IBM Heron R2 - 156 qubits (November 13, 2024) United States
IBM Eagle - 127 qubits (November 16, 2021) United States
Google Willow - 105 qubits (December 9, 2024) United States
USTC Zuchongzhi 3.0 - 105 qubits (March 3, 2025) China
Footnotes:
[1] Lindahl, N. (2025, July 4). The top 10 quantum computer leaderboard. The Lindahl Letter.
