A.A. di erogazione 2021/2022

Laurea Magistrale in FISICA
 (A.A. 2021/2022)


L'insegnamento è condiviso, tecnicamente "mutuato" con altri corsi di laurea, consultare il dettaglio nella sezione Mutuazioni
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Primo Semestre
Ore di attivita' frontale: 
Dettaglio ore: 
Lezione (66 ore)

The main objective of the course is to provide the basis for understanding the operating mechanisms of light detectors and the interpretation of measurement results in order to obtain information on relevant properties of optical states in the classical and quantum regimes. Emphasis will be placed on procedures for measuring the statistical and correlation properties of light. To this end, the most important results of experimental quantum optics will be discussed.
To achieve the course objectives, the theoretical lectures will be supported by experimental activities in the Department's Optics research laboratories, where students will practice making measurements of continuous-wave and pulsed optical states using different types of detectors.

By the end of the course, students will be able to.
- describe classical and quantum optical states
- describe different types of detectors
- discuss the differences between classical and quantum states in terms of non-classicality criteria
- illustrate the working principles of different detectors
- analyze the different detection schemes and their applicability to different optical states
- evaluate the performance and limitations of different detection schemes in relation to the type of light to be detected
- assemble an experimental setup to measure a light state by choosing the optimal detector and detection strategy.

Knowledge of electromagnetism and quantum mechanics.
Having attended the quantum optics course is useful but not mandatory.

Elements of quantum optics
- Classical and quantum description of radiation.
- Quantization of the electromagnetic field.
- Fock states
- Quadrature of the electromagnetic field.
- Coherent states, displacement operator.
- Pure states and mixed states.
- Representation of states.
- Characteristic function and Wigner function.
- Thermal states

Light detection theory
- Semiclassical theory.
- Quantum theory: POVM.
- Examples of POVM for various classes of detectors: ON/OFF and Bernoulli detectors.
- Beam splitter to model a non-ideal detector.
- Statistics of the detected light.
- Correlation measurements for detected photons.
- Optical detection schemes: direct and indirect detection.

Light detectors
- General characteristics of real detectors.
- Origin of noise in detectors.
- Acquisition systems and signal processing of detectors.
- Different classes of detectors:
-- Photomultipliers.
-- HPDS.
-- Photodiodes.
-- APD and SPAD.
-- SiPM.
-- Cryogenic detectors.
-- Superconducting detectors.
-- Cameras (CCD, EMCCD, ICCD, CMOS).
- Characterization of a detector with internal gain and amplification. Self-consistent procedure.
- Characterization of a detector with dark counting, cross talk, and afterpulses.

Application to optical state measurements
- Review of the state-of-the art in light detection.
- Experimental measurement of photon statistics and correlation by direct detection.
- Experimental measurement of field quadratures by homodyne detection and tomographic reconstruction of optical states.

The course objectives will be achieved through face-to-face lectures for a total of 40 hours. The teacher will use presentations and graphic tablet.
The remaining 26 hours will be devoted to laboratory sessions in which students will perform measurements on different states of light using different classes of detectors. Experimental activities will take place in the "Quantum Optics" and "Photophysics and Biomolecules" laboratories.
Guided data analysis procedures will also be presented and discussed.

Due to the extent of the subject matter and the lack of a comprehensive reference textbook, regular course attendance is strongly recommended.

The examination is in English and oral.
In preparation for the exam, students are asked to choose one of the experimental measurements performed in the laboratory, analyzing the data and thoroughly examining both the optical state and the detection scheme.

The first part of the exam is devoted to the discussion of the experimental results with the aim of verifying
- the knowledge of a specific detector and detection scheme and of the light state to be measured
- the understanding of the characteristics of the detector in relation to the specific application chosen
- the ability to thoroughly analyze the advantages and limitations of the chosen detection strategy.

In the second part of the exam, some questions are asked on the remaining topics, through which the teacher will check if the students
- have acquired a sufficient knowledge of the quantum properties of light and of the different ways to measure them
- have acquired the ability to distinguish between the various possibilities of detection and to design the one suitable for a given physical situation
- can correctly use mathematical and technical language to explain the processes involved in the detection of light.

A satisfactory presentation of Part 1 is required to pass the exam.
To successfully pass the exam, students should be familiar with all topics presented in the course. The deeper the knowledge, the better the grade.
Honors are awarded to students who, in addition to the points above, can critically discuss different topics by establishing connections and comparisons.

Lecture notes and slides will be available at the end of each developed topic.
Some possible reference texts are:
- Morgan W. Mitchell, "Quantum Optics for the Impatient"
- M. Fox "Quantum Optics, An Introduction", Oxford, 2006.
- HAS. Bachor and T.C. Ralph "A Guide to Experiments in Quantum Optics" Wiley 2004
- "Single-Photon Generation and Detection Physics and Applications", in Experimental Methods in Physical Sciences, Vol. 45, Pages 1-562 (2013), Edited by Alan Migdall, Sergey V. Polyakov, Jingyun Fan and Joshua C. Bienfang

Additional materials will be made available by the teacher.

For questions/comments students can contact the teacher by e-mail at the address:

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A.A. 2021/2022

Anno di corso: 2

A.A. 2020/2021

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