Introduction to quantum information processing

Wednesdays Room CE1 3 at 14h15 - 16h Course lectures 

Thursdays Room INF2 at 15h15 -17h exercises and sometimes first hour 15h15-16h dedicated to class and/or discussion (announced on moodle page day before).

Instructors:  nicolas.macris@epfl.ch  and yihui.quek@epfl.ch

Teaching assistant:  perrine.vantalon@epfl.ch

Student assistants: gopal.dahale@epfl.ch, cherilyn.christen@epfl.ch, timothe.jobin@epfl.ch, ekaterina.pankovets@epfl.ch

Description: Information is stored and processed in hardware components. With their miniaturization the concept of classical bit must be replaced by the notion of quantum bit. After having introduced the basics of quantum physics for "discrete" systems, the basic spin 1/2 qubit and its manipulation on the Bloch sphere are illustrated. This course then develops the subjects of communications, cryptography, quantum correlations, and introduces elementary concepts  of quantum physics with applications in information theory such as the density matrix and von Neumann's entropy. The course is intended for an audience with no knowledge of quantum physics and elementary knowledge of classical physics and linear algebra. Practical exercises, simulations and implementations on NISQ machines will also be covered during the semester. This course prepares students for more advanced quantum information classes.

Course and exercices are in presence. 

Lecture notes  (in french - we treat only a subset of these notes this semester)

Extra references for reading will also be given for some of the lectures (see in weekly schedule below)

Videos of class will be accessible here VIDEOS (these only serve as an aid and are not meant to replace in class presence. The material and order of classes and videos might also differ.)

Grading scheme: 4 graded homeworks 20%, miniproject 10%, final exam 70%. You will upload your homeworks on the moodle page.  The mini-project will start sometime during the second part of the semester.

Final exam: Tuesday 20.01.2026 from 09h15 to 12h15 rooms CE 1.1 (from Agrawal to Jouveaux), CE 1.3 (from Katanaev to Zouzou).

• Introduction and general overview of class
• Phenomenological illustration of strange quantum behaviors through interference experiments: Double slit experiment, Mach-Zehnder interferometer, (and photon polarization experiments if time permits).
• Classical physics prediction versus experiment. Quantum prediction.
  
• A math recap of linear algebra done in Dirac's notation.

Reading: Chapter 1 in notes, paragraphs 1.1 - 1.3. Chapter 3 paragraph 3.1.

Feynman lectures vol III Chap 1, Articles above "Double slit experiment: old and new" and "Interference of C60 molecules"

Extra reading to go further: rest of chapter 1

This week class Wed 14h15 - 16h and Thursday 15h15 - 16h. Exercises Thursday 16h - 17h.

Instructor Nicolas Macris

• Physical examples of qubits: photon polarization, spin 1/2, two level systems
  
• Application of principles to the Mach-Zehnder interferometer and the double slit experiment
  
• Application of principles to photon polarization experiments
• Quantum versus classical prediction (revisited)

Reading: Chap 2.1 -2.4 of notes for extra information. Paragraphs 2.5 - 2.7 on spin will be treated later on during the semester.

First Graded HW - upload your hmw before the deadline Thursday October 2nd at 23h59. A single pdf file, handwritten, or latexed.

Instructor Nicolas Macris

Secret Key Distribution (QKD) protocols: BB84, B92

Reading: Chap 5 of notes and in Nielsen and Chuang Chap 12 section 6 

Class Wednesday 14h15 - 16h room CE 1 3 and Thursday 15h15 - 16h room INF2 ; Exercises Thursday 16h15 - 17h room INF2

Instructor Yihui Quek

Entanglement, quantum teleportation, dense coding

Reading: Chap 6 sections 6.1, 6.3, 6.4

This Thursday, we finish the class of Wednesday during the first half hour. 

Second Graded HW: upload your hmw before the deadline Thursday October 16th at 23h59. A single pdf file, handwritten, or latexed.

Instructor Nicolas Macris

Bell inequalities, Ekert 1991 protocol for QKD

Reading: chap 6 paragraph 6.2

On thursday: 2 hours of hmw room INF2 15h15-17h (finishing the graded one and starting hmw 6 for those that have finished)

Instructor Nicolas Macris

statistical mixtures, system+environment, generalization of the notion of quantum state and the density matrix

Reading: parts of Chap 4 of notes: paragraphs 4.1 - 4.3

This thursday: we finish class from 15h15 - 16h. Exercise session after 16h - 17h

Instructor Nicolas Macris

von Neumann entropy

Reading: parts of chap 4 and 7: paragraph 4.4 and 7.1 - 7.3

Instructor Yihui Quek

Schmidt theorem, Entanglement entropy, Examples

Reading: Notes of last week and/or parts of chap 7.

Third Graded HW

Instructor Yihui Quek

Reading: 

Instructor Yihui Quek

Reading:

Instructor Yihui Quek

Graded HW4

Instructor Yihui Quek

- Introduction to magnetic moments, spin, Bloch sphere representation, Larmor precession

Reading: Chap 2 (2.5 - 2.10) and Chap 15 (15.1 - 15.3) of notes. 

If you want to read more on the Stern-Gerlach experiments see Feynman Lectures vol III, chap 5 & 6 (will not be needed in this class)

Instructor Nicolas Macris

This and next thursday two hours of exercises. The project assignment is already available in this weekly block.

Class of Wednesday

- Rabi oscillations

- Application to elementary gates (NOT and Hadamard logical gates)

- Heisenberg spin-spin interactions if time permits (and CNOT gate)

Reading: Chap 15 (15.4 - 15.5) of notes.

Heisenberg interaction, manipulation of qubit pairs

Reading: Chap 16 of notes