Positionnement dans le cursus
Semestre 5
Intersemestre
Semestre 6
 
 
 
Semestre 7
 
Intersemestre
Semestre 9
 
 
Intersemestre

Course unit

Quantum physics: mathematical basis and formalism

Last updated: 22/02/2024

Edit

Course Director(s):

CHARRIERE Renée FISCHER Marc

General Description:

Mathematics for quantum physics (M. Fischer) :
In quantum mechanics, the state of a physical system is described by a wave function. This function can be seen as a point in a (vector) space as in classical mechanics except that this point (or vector) actually lives in a space of infinite dimension, since it is a (linear) space of functions. It turns out that the classical Euclidean vision can be extended to the spaces of quantum mechanics, thanks to the central concept of Hilbert space: a complete normalized vector space whose norm (metric) is derived from a scalar product as for the Euclidean spaces. The usual Hilbert spaces are built using the Lebesgue integral theory. A first work will be to see how a wave function in a Hilbert space can be described by an infinite (but often discrete) system of coordinates thanks to the notion of orthonormal basis or Hilbert basis. This will also make it possible to interpret in the formalism of quantum mechanics a wave function as an infinite superposition of states with a priori probabilities (apart from any measure) more or less important. The coherence of such a formalism will be ensured by the Bessel-Parseval relation. In addition, Fourier analysis will appear to be a very particular case. A second work will focus on simply describing a sufficiently rich class of linear applications (or operators on a Hilbert space) in terms of spectral decomposition as in the case of finite dimension. In the formalism of quantum mechanics, this will make it possible to analyze the result of an observable or measurement since the latter is "naturally" associated with a self-adjoint operator... Finally, the example of the quantum harmonic oscillator will be studied in detail to illustrate the different concepts, in particular of symmetry and compactness of an operator.

Introduction to Quantum Mechanics (R. Charrière) :
The course Introduction to quantum mechanics presents the theoretical and conceptual bases necessary for the description of phenomena on the atomic scale. The course will start with a reminder of the historical experiences that led to the development of quantum mechanics. The formalism will then be presented, with the fundamental concepts (bra, ket, operators, eigenvectors and eigenvalues ​​...) and the various basic principles (superposition principle, Shrödinger's equation, principle of quantum measurement ...) . The second part of the course will be devoted to the calculation of quantum states and energy levels of the hydrogen atom, with the presentation of the  quantum angular moment operator and its properties. The fine structure of the hydrogen atom will also be mentioned, calculated using the perturbations method.

Key words:

Quantum mechanics energy levels and quantum states hydrogen atom Hilbert space Hilbertian basis Operator Operator spectrum

Number of teaching hours

30

Fields of study

Materials Science Mathematics

Teaching language

French

Intended learning outcomes

On completion of the unit, the student will be capable of: Classification level Priority
understand geometry in Hilbert spaces as an extension of usual 3D geometry 2. Understand Important
decompose a vector on a Hilbert basis 3. Apply Essential
analyze the spectral decomposition of some self-adjoint operators 4. Analyse Useful
study a simple case of operator from quantum mechanics 4. Analyse Useful
Understand the concepts and formalism of quantum mechanics 2. Understand Essential
Understanding the calculation of quantum states and energy levels of the hydrogen atom 2. Understand Essential
Calculate quantum states and energy levels of simple systems 3. Apply Essential
Know the perturbation theory and the fine structure of the hydrogen atom 1. Knowledge Important

Learning assessment methods

Percentage ratio of individual assessment Percentage ratio of group assessment
Written exam: 100 % Project submission: 0 %
Individual oral exam: 0 % Group presentation: 0 %
Individual presentation: 0 % Group practical exercise: 0 %
Individual practical exercise: 0 % Group report: 0 %
Individual report: 0 %
Other(s): 0 %

Programme and content

Type of teaching activity Content, sequencing and organisation
Course

Mathematics for quantum physics :
Introduce geometry in spaces of infinite dimension with the case of functional spaces
Define Hilbert spaces and decomposition on an orthonormal basis or Hilbert basis
Define and study some self-adjoint operators on a Hilbert space.
Explain the topological notion of compactness and the central role of this notion in infinite dimension: a self-adjoint and compact operator has a discrete spectrum

Introduction to Quantum Mechanics :
(12h) (cf. general description) Presentation of quantum formalism, calculation of energy levels and quantum states of the hydrogen atom ... 

Tutorials

Mathematics for quantum physics :
Construction of orthonormal bases for usual function spaces with the Gram-Schmidt orthonormalization process
Study of the quantum harmonic oscillator ...

Introduction to Quantum Mechanics :
(3h) Exercises to understand the results obtained during fundamental experiments: the maser (micrometric wave laser), the Stern and Gerlach experiment
These exercises will allow to manipulate the concepts and formalisms seen in class.