Quantum computing hardware and software company IonQ says it has developed a quantum error correction decoder that runs in real time on a single conventional CPU, potentially reducing classical computing overhead that can slow down larger quantum systems. In simulations with up to 408 logical qubits, the company’s decoder increased processing time by just 0.02% under normal operating noise conditions.
Quantum computing derives its power from qubits, a special type of “bit” that can assume one of many states between the traditional binary on/off state of classical computing. The main problem with qubits is that these “superimposed” states, which are neither on nor off, are extremely sensitive to ambient noise and very easily break down and revert to the binary state, which is unusable for quantum computers.
We refer to operational qubits as “logical” and the much larger number of additional qubits required to find a collapsed “logical” qubit as “physical” qubits. The current solution is to have many more physical qubits capable of locating every faulty (collapsed) logical qubit – but it requires slower classical computations to decipher the information provided by the larger number of physical qubits.
This process results in a delay in the speed and performance provided by the quantum computer, but the successful end result is more fault-tolerant and therefore more powerful quantum computing. But continuing to build more powerful quantum computers brings with it an additional ironic trade-off. More powerful quantum computing is generally the result of using more logical qubits. But each new logical qubit requires a large number of additional physical qubits to maintain error correction.
The growth in the number of qubits and their fragility inevitably require an increase in the delay caused by classical quantum error decoding.
IonQ has announced a new solution to this major bottleneck caused by classical computing – a new end-to-end real-time quantum error correction decoder that runs on a single standard classical computing CPU. In our own research published on arXivIonQ simulated up to 408 logical qubits across 88 memory blocks and magic factories (functional zones that separately process data storage and complex calculations).
“At normal operating noise, IonQ’s decoder resulted in a stretch time of only 0.02%. This means that the decoding overhead added virtually no delay to the overall quantum computation,” claims IONQ.
Nicolas Delfosse, head of quantum research at IonQ, added: “The successful validation of real-time decoding across hundreds of logical qubits and across millions of logical operations is an important milestone. Furthermore, the fact that our decoder runs on a single CPU provides a practical path to fault-tolerant quantum computing at commercial scale.”
IonQ claims its new error-correcting decoder confirms that classical hardware overhead does not need to scale exponentially as quantum systems become wider in logical qubits or deeper in operations, and provides a confirmed roadmap for more powerful quantum computers.
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