In a recent study published in Physical Review Letters, Professor Wei Guo from Florida State University provided valuable insights into the quantum states of electrons on qubits.
A diagram of an electron-on-solid-neon quantum bit. Image Credit: Wei Guo
Quantum computers have the potential to revolutionize technology by performing calculations that would take classical computers many years to complete.
To build an effective quantum computer, a reliable quantum bit, or qubit, is essential. A qubit must be able to exist simultaneously in both the 0 and 1 states for a sufficiently long period, known as its coherence time.
One promising approach involves trapping a single electron on a solid neon surface, creating what is known as an electron-on-solid-neon qubit.
Guo’s team discovered that small bumps on the surface of solid neon can naturally bind electrons, forming ring-shaped quantum states. These quantum states describe various properties of an electron, such as position, momentum, and other characteristics before measurement. When these bumps are of a certain size, the electron’s transition energy—the energy required for an electron to move from one quantum ring state to another—aligns with the energy of microwave photons, another type of elementary particle.
This alignment allows for the controlled manipulation of electrons, which is crucial for quantum computing.
This work significantly advances our understanding of the electron-trapping mechanism on a promising quantum computing platform, it not only clarifies puzzling experimental observations but also delivers crucial insights for the design, optimization, and control of electron-on-solid-neon qubits.
Wei Guo, Professor, Florida State University
Guo and collaborators previously demonstrated the feasibility of a solid-state single-electron qubit platform using electrons trapped on solid neon. Recent research has revealed coherence times of up to 0.1 milliseconds—100 times longer than the typical 1 microsecond coherence time for conventional semiconductor-based and superconductor-based charge qubits.
The extended coherence time of the electron-on-solid-neon qubit is attributed to the inertness and purity of solid neon. This system also addresses the issue of liquid surface vibrations, a problem inherent in the more extensively studied electron-on-liquid-helium qubit. The current research provides crucial insights into further optimizing the electron-on-solid-neon qubit.
A key aspect of this optimization involves creating qubits that are smooth across most of the solid neon surface while having bumps of the right size where needed. Designers aim to minimize naturally occurring surface bumps that attract disruptive background electrical charge. Simultaneously, intentionally fabricating bumps of the correct size within the microwave resonator on the qubit enhances its ability to trap electrons effectively.
This research underscores the critical need for further study of how different conditions affect neon qubit manufacturing, Neon injection temperatures, and pressure influence the final qubit product. The more control we have over this process, the more precise we can build, and the closer we move to quantum computing that can solve currently unmanageable calculations.
Wei Guo, Professor, Florida State University
Toshiaki Kanai, a Graduate Research Student in the FSU Department of Physics, and Dafei Jin, an Associate Professor at the University of Notre Dame are the Co-authors of the study.
The National Science Foundation, the Gordon and Betty Moore Foundation, and the Air Force Office of Scientific Research supported the research.
Journal Reference:
Kanai, T., et al. (2024) Single-Electron Qubits Based on Quantum Ring States on Solid Neon Surface. Physical Review Letters. doi.org/10.1103/PhysRevLett.132.250603.