RQC Seminar

307th RQC Seminar

• Speaker

  Dr. Jeonghun Sohn
  ( Pohang University of Science and Technology, Republic of Korea )

• Date

  16:00-17:00, (4:00 p.m.-5:00 p.m.) Friday, October 9, 2026

• Venue

  Hybrid(Zoom, Wako Main Research 3F 345-347 Seminar Room / 研究本館3階 セミナー室(345-347) C01）

• Title

  A phonon erasure qubit with symmetry-matched rails: the chirality dual rail

• Inquiries

  norilab_rqc_assist[at]ml.riken.jp

Abstract
In this talk, I will introduce a phonon erasure qubit encoded in the chirality of two mechanical modes. A single phonon shared between modes of opposite chirality forms a dual-rail qubit, while phonon loss takes the state outside the logical subspace and can be heralded. The central feature is that the two rails are matched by the mode structure of a C₃-symmetric device. For independent local loss channels and ideal mode profiles, their equal spatial weights enforce identical diagonal decay rates, eliminating the associated differential attenuation of logical superpositions. Using analytical models and numerical simulations, we investigate how this matching suppresses logical errors and identify residual effects of mode mixing and thermal noise. We also analyze finite-duration erasure checks and the feasibility of quantum nondemolition detection that preserves logical coherence. Finally, I will discuss a concrete device candidate and the costs of single-qubit control, outlining a route toward phononic erasure qubits with symmetry-matched rails.