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This content will become publicly available on December 1, 2024

Title: Overcoming leakage in quantum error correction
Abstract

The leakage of quantum information out of the two computational states of a qubit into other energy states represents a major challenge for quantum error correction. During the operation of an error-corrected algorithm, leakage builds over time and spreads through multi-qubit interactions. This leads to correlated errors that degrade the exponential suppression of the logical error with scale, thus challenging the feasibility of quantum error correction as a path towards fault-tolerant quantum computation. Here, we demonstrate a distance-3 surface code and distance-21 bit-flip code on a quantum processor for which leakage is removed from all qubits in each cycle. This shortens the lifetime of leakage and curtails its ability to spread and induce correlated errors. We report a tenfold reduction in the steady-state leakage population of the data qubits encoding the logical state and an average leakage population of less than 1 × 10−3throughout the entire device. Our leakage removal process efficiently returns the system back to the computational basis. Adding it to a code circuit would prevent leakage from inducing correlated error across cycles. With this demonstration that leakage can be contained, we have resolved a key challenge for practical quantum error correction at scale.

 
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Award ID(s):
1747426
NSF-PAR ID:
10479841
Author(s) / Creator(s):
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Publisher / Repository:
Nature
Date Published:
Journal Name:
Nature Physics
Volume:
19
Issue:
12
ISSN:
1745-2473
Page Range / eLocation ID:
1780 to 1786
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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