RQC Seminar

239th RQC Seminar

• Speaker

  Prof. Ku Huan-Yu
  ( National Taiwan Normal University )

• Date

  16:00-17:00 (4:00 p.m.-5:00 p.m.), October 22, 2025 Wednesday

• Venue

  Hybrid(ZOOM・ Seminar Room 445-447 at 4F in Wako Main Research Building / 研究本館4階 セミナー室 (445-447) (C01))

• Title

  Channel Distillation via Coherent Control

• Inquiries

  norilab_rqc_assist[at]ml.riken.jp

Abstract
The fundamental limitations of channel distillation, determined by channel capacity and channel resource theory, constrain the potential advantages achievable in quantum communication and computation. In this talk, we show how to overcome this essential obstacle with a coherent-control framework enabling channel distillation beyond all previously known limits.
Coherent control of quantum channels allows different channels, acting on a particle's internal degrees of freedom, to be applied depending on its path degree of freedom, which can be in a coherent superposition. We show that for any noisy quantum channel, there always exists a coherent control procedure that allows one to filter, i.e., probabilistically obtain, a noiseless channel, i.e., unitary. Perfect filtering is achieved in the limit of the coherent control of infinitely many copies of the channel, possibly and rather counterintuitively, after the injection of additional noise. We estimate (1) the optimal distillation probability, providing also the necessary and sufficient condition for distillation, (2) the required number of copies to achieve the upper bound of distillation error, and (3) a complete recipe on the perfect channel distillation problem. Since coherent control procedures are typical of interferometry experiments, our results provide a practical application from the perspective of quantum advantages in communication and computation.