7/22/2023 0 Comments Fraction converter![]() For example, a four-qubit quantum code is sufficient to correct a single erasure error 19, and the surface code threshold under the erasure channel approaches 50% (with perfect syndrome measurements), saturating the bound imposed by the no-cloning theorem 20. ![]() Erasures are significantly easier to correct than depolarizing errors in both classical 18 and quantum 3, 19 settings. On the other hand, many qubits also exhibit some level of leakage outside of the computational space 6, 16, which requires extra gates in the form of leakage-reducing units, decreasing the threshold 17.Īnother type of error is an erasure, or detectable leakage, which denotes an error at a known location. The realization of biased noise models and bias-preserving gates for Rydberg atom arrays has also been discussed 15. For example, qubits encoded in cat-codes in superconducting resonators can have strongly biased noise 11, leading to significantly higher thresholds 12, 13 given suitable bias-preserving gate operations for fault-tolerant syndrome extraction 14. While many codes have been studied in the context of the abstract model of depolarizing noise arising from the action of random Pauli operators on the qubit, the realistic error model for a given qubit platform is often more complex, which presents both opportunities and challenges. ![]() The threshold error rate depends on the choice of error correcting code and the nature of the noise in the physical qubit. Fault-tolerant protocols for error correction and logical qubit manipulation have recently been experimentally demonstrated in several platforms 7, 8, 9, 10. If the logical qubit operations are implemented in a fault-tolerant manner that prevents the proliferation of correlated errors, the logical error rate can be suppressed arbitrarily so long as the error probability during each operation is below a threshold 5, 6. Quantum error correction 2, 3, 4 allows multiple physical qubits to represent a single logical qubit, such that the correct logical state can be recovered even in the presence of errors on the underlying physical qubits and gate operations. However, the inherent fragility of quantum states and the finite fidelity of physical qubit operations make errors unavoidable in any quantum computation. Scalable, universal quantum computers have the potential to outperform classical computers for a range of tasks 1. Erasure conversion should benefit any error correcting code, and may also be applied to design new gates and encodings in other qubit platforms. ![]() We also observe a larger code distance near the threshold, leading to a faster decrease in the logical error rate for the same number of physical qubits, which is important for near-term implementations. We quantify the benefit of this approach via circuit-level simulations of the surface code, finding a threshold increase from 0.937% to 4.15%. We estimate that 98% of errors can be converted into erasures. The key idea is to encode qubits in a metastable electronic level, such that gate errors predominantly result in transitions to disjoint subspaces whose populations can be continuously monitored via fluorescence. In this work, we propose a qubit encoding and gate protocol for 171Yb neutral atom qubits that converts the dominant physical errors into erasures, that is, errors in known locations. ![]() Recently, the development of error correcting codes tailored to particular physical noise models has helped relax these requirements. Executing quantum algorithms on error-corrected logical qubits is a critical step for scalable quantum computing, but the requisite numbers of qubits and physical error rates are demanding for current experimental hardware. ![]()
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