The world’s first commercial error-tolerant quantum computer with “logical qubits” could start operating before the end of the year. Logical qubits, which connect physical quantum bits or qubits through quantum entanglement, reduce errors in quantum computers by storing the same data in different locations.

Representatives from QuEra, the company building the machine, announced that the new device, with 256 physical and 10 logical qubits, will be released to the market by the end of 2024.

Harvard, QuEra, and researchers from other institutions previously showcased a quantum computer with the highest number of logical qubits tested to date, featuring 48 logical qubits. The recent announcement followed this achievement. Harry Zhou, a co-author of the study and a physicist at QuEra and Harvard University, stated, “This is the first machine with quantum error correction.”

Zhou mentioned that while this computer may not have enough power to be useful on its own, it provides a platform for software programmers to start testing code for future quantum computers.

Why is Error Correction Needed?

Traditional computers store information in bits with values of 0 or 1, whereas a qubit’s general state, according to quantum mechanics, can exist in a quantum superposition of both 0 and 1. Qubits can also be brought together in multiple states simultaneously using quantum entanglement, allowing them to perform many calculations much faster than classical computers. However, qubits are easily prone to errors, making them error-prone.

While quantum computers with millions of qubits could outperform the best supercomputers, natural errors limit scalability. Moreover, the largest quantum computer built to date has only about 1,000 qubits. This is where error correction comes into play, with logical qubits being one of the methods used in quantum error correction.

Logical Qubits

The new error correction system relies on data redundancy, where the same data is stored in multiple locations. Logical qubits perform the same calculations on multiple physical qubits, significantly reducing error rates if one or more physical qubits fail, allowing calculations to continue.

These new qubits have made significant progress compared to their predecessors. Google made a groundbreaking step in quantum computers last year by introducing logical qubits. In their research, Google demonstrated a system with 49 physical qubits that achieved an error rate of 2.9%. QuEra’s error rate, with 48 logical qubits, has now reached 0.5%.

IBM also demonstrated error correction technology in its 127-qubit Heron chip last year, reducing error rates five times compared to other chips. However, the production of the first commercial error-tolerant machine is not expected until 2029.

In the coming years, QuEra plans to release several quantum computers starting with a machine featuring 30 logical qubits and 3,000 physical qubits in 2025. The company also states that a machine with over 10,000 physical qubits and 100 logical qubits will be launched in 2026, capable of accurate calculations surpassing the capacities of today’s supercomputers.