Quantinuum, in collaboration with the University of Colorado, has made a significant breakthrough in the field of quantum computing. They have successfully entangled four logical qubits, which have a higher fidelity than their physical counterparts. This achievement is a significant step towards developing practical and scalable quantum computers.
The researchers implemented error-correcting codes, specifically high-rate non-local quantum Low-Density Parity-Check (qLDPC) codes, on Quantinuum’s H2 quantum processor. These codes are crucial for improving the accuracy of quantum operations, enhancing error protection, and operational reliability, all essential aspects for the practical realization of quantum computers.
Quantum error correction is a critical component in the quest for reliable and practical quantum computers. Quantum systems are inherently fragile, susceptible to errors from environmental interference and imperfect operations. To mitigate these errors, quantum information must be encoded into several entangled qubits, forming what is known as a “logical qubit.” However, this process has traditionally been resource-intensive.
The high-rate qLDPC code implemented by Quantinuum and the University of Colorado allows for a much higher rate of logical qubits per physical qubit, making it possible to scale quantum machines more efficiently than with traditional codes. The researchers detailed their success in creating four error-protected logical qubits and entangling them in a Greenberger-Horne-Zeilinger (GHZ) state. The error correction code improved the fidelity of the GHZ state preparation, achieving better results than performing the same operation on physical qubits alone.
The implementation demonstrated that the logical qubits encoded using the high-rate qLDPC code achieved fidelities between 99.5% and 99.7%, surpassing the fidelities of uncorrected physical qubits, which ranged between 97.8% and 98.7%. This achievement marks the first time anyone has entangled four logical qubits with better fidelity than their physical counterparts.
The researchers also emphasized the importance of this work in making quantum computing more accessible to a broader range of researchers and developers, reducing the barrier to entry for quantum programming. They achieved this advance with a small team, half of whom did not have specialized knowledge about the underlying physics of the processors. This level of accessibility places Quantinuum ahead of the competition in terms of both reliability and ease of use.
The research team included Yifan Hong and Andrew Lucas from the Department of Physics and Center for Theory of Quantum Matter, University of Colorado, Boulder, and Elijah Durso-Sabina and David Hayes from Quantinuum. For more technical details, readers can refer to the ArXiv paper. To learn more about the H2 system, visit Quantinuum’s product page.
