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Demonstration of Measurement-Enhanced State Preparation and Erasure Conversion in a Molecular Tweezer Array

Connor M. Holland1, Yukai Lu1,2, Samuel J. Li1, Callum L. Welsh1, and Lawrence W. Cheuk1,*

  • *Contact author: lcheuk@princeton.edu
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Phys. Rev. X 15, 031018 – Published 16 July, 2025

DOI: https://doi.org/10.1103/8q8p-mx1l

Abstract

Programmable optical tweezer arrays of molecules are an emerging platform for quantum simulation and quantum information science. For these applications, the reduction and mitigation of errors remain major challenges. In this work, we leverage the rich internal structure of molecules to mitigate two types of errors—internal state preparation and qubit leakage errors. First, we demonstrate robust measurement-enhanced tweezer preparation at a record fidelity using site-resolved error detection followed by tweezer movement. Second, using a new hyperfine qubit encoding well suited for use as a quantum memory, we demonstrate site-resolved detection of qubit leakage errors (erasures) induced by blackbody radiation. This approach constitutes the first demonstration of erasure conversion in molecules, a capability that has found recent interest in quantum error correction. Our work opens the door to new possibilities with molecular tweezer arrays: Measurement-enhanced preparation opens access to mesoscopic defect-free molecular arrays that are important for quantum simulation of interacting many-body systems; erasure conversion in molecular arrays lays the technical groundwork for midcircuit detection, an important capability for explorations in quantum information processing.

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Popular Summary

Programmable arrays of molecules trapped in optical tweezers are a promising new platform for quantum science. These systems combine the complex structure and interactions of molecules with precise spatial control, opening new possibilities in quantum computing, quantum simulation, and quantum metrology. However, like all quantum platforms, they suffer from errors that must be addressed to reach practical usefulness. In our study, we develop new error mitigation schemes to tackle two major types of errors—state preparation errors and qubit leakage.

To do this, we use a strategy where molecules with errors are encoded in “bright” internal states that can be easily detected, while error-free molecules remain in “dark” states that are unaffected. This approach enables us to identify the molecules with errors and potentially remove them afterwards. For state preparation, we develop a new measurement-based protocol that achieves record levels of array preparation fidelities. For qubit leakage, we show that unwanted transitions caused by background blackbody radiation can be converted into detectable local errors—called erasures—that can be filtered out during analysis, significantly improving the qubit’s lifetime and coherence.

Our results mark the first demonstration of this type of error mitigation in molecular systems, a key step toward quantum error correction. With our state preparation protocol, we can also create large, defect-free arrays of molecules, a prerequisite for simulating quantum many-body systems. Moreover, our methods for detecting and removing qubit errors pave the way for midcircuit measurements, a powerful tool for new and more reliable quantum technologies with molecules.

Article Text

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Phys. Rev. X 15, 031018– Published 16 July, 2025
  • Received 18 June 2024
  • Accepted 17 June 2025
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