Course code TPT18
Course title Quantum entanglement for communications: from theory to experiments
Institution TELECOM ParisTech
Course address The theoretical part (4 days) will take place at TELECOM ParisTech (Paris 13) and the experimental part (1 full day) at Institut d'Optique Graduate School in Palaiseau (accessible with RER B ; the students will be guided)
City Paris and Palaiseau
Minimum year of study 4th year
Minimum level of English Good
Minimum level of French None
Key words

entanglement, spontaneous down conversion, quantum optics, EPR paradox, Bell inequalities, quantum teleportation

Language English
Professor responsible Isabelle Zaquine
Telephone 01 45 81 78 39
Fax 01 45 81 76 46
Participating professors

Gaëtan Messin, Lionel Jacubowiez, Eleni Diamanti, Damian Markham, Isabelle Zaquine

Number of places Minimum: 8, Maximum: 12, Reserved for local students: 2
Objectives Quantum entanglement is the basic ressource for the future quantum relays or repeaters. The objective of this  course is to acquire a thorough understanding of this concept from the theoretical definition to the practical implementation of entangled photons states, using non linear optics and to see how it can be used in various quantum communications devices.
Programme to be followed

Basic quantum physics

Entanglement,  EPR paradox, Field quantization, beamsplitters

Introduction to nonlinear optics (second order nonlinear phenomena)

Entangled photons: polarization, time-energy, time-bin

Physical implementation of entangled photon pairs sources

Quantum teleportation, entanglement swapping

Quantum cryptography protocols using entangled states

Two experiments in IOGS:

1) Quantum coalescence of identical bosons : two-photon interference effect using pairs of  identical photons produced by degenerate spontaneous down-conversion.

Identical  photons can exhibit a very strange property: when they enter a different input port of a balanced beam splitter, they leave the beam splitter through the same output port. This effect, can be understood as a two-photon quantum interference between two possible paths taken by the photons. The contrast of the interference signal is a measurement of the degree of indistinguishability of the light particles. Recent proposals for the building of a quantum computer rely on the ability to produce indistinguishable photons and rely on this so called HOM interference.

2) Quantum mechanics non locality test: violation of Bell's inequalities using polarization entangled photons produced by spontaneous down-conversion.

The famous EPR paradox about completeness of quantum mechanics raised by Einstein, Podolsky and Rosen in 1935 [1], initially seen as a philosophical question, became a physical problem when John Bell published an article in 1964 suggesting that it was possible to actually test the hypothesis of local hidden variables [2]. It took ten more years before an experimental implementation of the test could be conducted by Clauser et al. [3], and a little more before a clear and widely accepted demonstration of the Bell's inequality violation, by A. Aspect et al., at Institut d'Optique [4]. This test is now routinely used in labs to measure the quality of entanglement, a fundamental ressource for quantum information processing and communications.


Maxwell equations

Course exam

Daily exercises and the laboratory session