RQC Seminar

229th RQC Seminar

• Speaker

  Prof. Li FuLi
  ( Xi'an Jiaotong University )

• Date

  11:00-12:00 (11:00 a.m. - 12:00 p.m.), November 4, 2025 Tuesday)

• Venue

  Hybrid(ZOOM・ Wako Chemistry and Materials Physics Building 5F S507 Meeting Room / 物質科学研究棟5階 S507 会議室 (S51))

• Title

  Antibunching Photon Emission in a Josephson-Photonics Circuit

• Inquiries

  yasunobu.nakamura[at]riken.jp

Abstract
Nonclassical photon emission source is one of key devices in the field of quantum information and quantum computation. In this talk, I shall introduce a scheme for generating antibunching N-photon bundles by a dc voltage-biased Josephson junction in series with a superconducting microwave resonator and a charge qubit. Each resonant tunneling Cooper pair leads to the excitation of both the charge qubit and resonator with N photons simultaneously via the ac Josephson effect. Since the strong anharmonicity of the charge qubit regulates the tunneling behavior of the Cooper pairs, the presence of N photons in the resonator prevents the next tunnel event. As a result, the resonator contains either only N photons or none, and all other possible events are greatly suppressed. Through the dissipation process, the resonator can emit its energy in antibunching bundles of N strongly correlated photons with high purity and an in situ tunable emission rate. I shall also talk about the photon-pair blockade in a Josephson-photonics circuit consisting of a dc voltage-biased Josephson junction in series with a superconducting charge qubit and two nondegenerate microwave resonators. When the Josephson frequency matches the sum of resonance frequencies of the charge qubit and the two resonators, the two resonators can release their energies in the form of antibunching pairs of two strongly correlated photons. In addition, I shall also introduce an efficient scheme for the unidirectional emission of a tunable squeezed microwave field in the magnon-photon coupling. We show that the unidirectional emission of a tunable squeezed microwave field can be generated via the assistance of the dissipative magnon mode and a waveguide. These nonclassical photon emission schemes are feasible in current experiments and could be useful in the field of quantum information science and technology.