Measuring the number of photons in a microwave mode

Item: Measuring the number of photons in a microwave mode
Rating: 4
Author: PostSingularity Institute

by Benjamin Huard

Formal & Physical Sciences Physics PHPhysics PHQQuantum physics (quantum mechanics and quantum field theory)

🎙 Benjamin Huard 👥 1K 📅 October 5, 2020 ⏱ 93 min 👁 566 📄 original study 🧭 2026-08-18

Available in: English (current) Français

Keywords

photon numbermicrowavequbitmultiplexingquantum memory

Summary

In this seminar, Professor Benjamin Huard presents two experiments addressing challenges in counting photons in microwave modes. The first experiment uses a single superconducting qubit to multiplex photon number measurements, avoiding sequential repetition. The second converts a stationary mode counter into a photocounter for traveling wave packets using a quantum memory. The talk covers the theoretical background, experimental setup, and results, highlighting the importance of these techniques for quantum information processing. The presentation includes detailed explanations of dispersive coupling, reflection coefficients, and Wigner tomography. The speaker also discusses the potential for simultaneous measurement and the use of frequency combs. The seminar is technical and aimed at an audience familiar with quantum optics and circuit QED.

115 words

Critical Evaluation

Value of the Information & Strength of the Argument

The talk provides valuable insights into advanced photon counting techniques, with clear explanations of the underlying principles and experimental implementations. The argumentation is solid, supported by experimental data and references to published papers. The speaker effectively demonstrates the advantages of multiplexing and quantum memory approaches, addressing key limitations of existing methods.

60 words

Title / Content Match

The title accurately reflects the content, which focuses on techniques for measuring photon numbers in microwave modes.

Quality & Reliability

8/10

The talk is based on two peer-reviewed papers published on arXiv, with detailed experimental descriptions and theoretical backing. The speaker is a recognized expert in quantum circuit QED. However, the video is a seminar recording with limited production quality, and the transcription is imperfect.

Key Moments

Markers derived by PSI from the transcript: the creator did not define chapters.

Cited Sources

Multiplexed photon number measurement — Related paper [1]
Number-resolved photocounter for propagating microwave mode — Related paper [2]
Quantum Circuit Group, ENS de Lyon — Other link
UTS Centre for Quantum Software and Information — Other link
Associate Professor Nathan Langford — Other link

Concurring Sources

Multiplexed photon number measurement — Paper directly related to the first experiment
Number-resolved photocounter for propagating microwave mode — Paper directly related to the second experiment

Contribution & Novelties

The talk presents novel experimental techniques for photon number measurement, specifically multiplexing and quantum memory approaches, which improve efficiency and enable counting of traveling photons. These contributions advance the field of quantum information processing.

Pour aller plus loin :

Circuit quantum electrodynamics — Provides background on the interaction between superconducting qubits and microwave resonators.
Quantum non-demolition measurement — Relevant to the measurement techniques discussed.
Wigner function — Used for characterizing quantum states in the experiments.

75 words

Radar Profile

The radar profile shows high scores in technical level and information quality, with slightly lower scores in quantity and reliability, reflecting the specialized nature and the reliance on experimental data.

Reliability 8/10