RQC Seminar

107th RQC Seminar

• Speaker

  Prof. Ludovico Lami
  ( QuSoft / University of Amsterdam )

• Date

  16:00-17:00, March 18, 2024 (Monday)

• Venue

  Hybrid(ZOOM・ Wako Welfare and Conf. 2F Large Meeting Room C61）

• Title

  Exact solution for the quantum and private capacities of bosonic dephasing channels

• Inquiries

  rqc_info[at]ml.riken.jp

Abstract
The capacities of noisy quantum channels capture the ultimate rates of information transmission across quantum communication lines, and the quantum capacity plays a key role in determining the overhead of fault-tolerant quantum computation platforms. In the case of bosonic systems, central to many applications, no closed formulas for these capacities were known for bosonic dephasing channels, a key class of non-Gaussian channels modelling, e.g., noise affecting superconducting circuits or fiber-optic communication channels. Here we provide the first exact calculation of the quantum, private, two-way assisted quantum, and secret-key agreement capacities of all bosonic dephasing channels. We prove that that they are equal to the relative entropy of the distribution underlying the channel to the uniform distribution. Our result solves a problem that has been open for over a decade, having been posed originally by [Jiang ＆ Chen, Quantum and Nonlinear Optics 244, 2010].

Reference: Nature Photonics 17, 525–530 (2023)