Classical and Quantum dynamics with Optical Frequency Combs

Classical and Quantum dynamics with Optical Frequency Combs: a multimode approach

Internship and PhD thesis research project

Optical frequency combs have revolutionized frequency metrology and found application from fundamental constants measurements and optical clocks, to spectroscopy and telecommunications. They are becoming key elements of more and more advanced experiments as they offer unprecedented properties in terms of spectral purity, pulse repetition rate stability and spectrum spanning. It is thus crucial to get a better understanding of the noise sources and coupling mechanisms that directly impact the performances.

On the other hand, quantum optics has been, from its beginning, the driving force both for the exploration of fundamental limits of the quantum world and for conceiving seminal ideas and applications of the so-called quantum technologies. The last 20 years have seen a rapid development of ideas and proof-of-principle experiments involving the fields of quantum communication, quantum computation, quantum metrology and quantum simulation.

In the photonic scenario single photons are the traditional carriers of quantum information, but the scalability and adaptability of quantum resources is still an open problem. The system developed in the Quantum Optics group of the Laboratoire Kastler Brossel is based on a complementary approach where the information is not encoded on discrete variables, like the number of photons, but in continuous variable of the electromagnetic field, i.e. its amplitude and phase. In our approach, in the case of Gaussian quantum states, the resource to be scaled-up is the number of modes in which these states of light are simultaneously and deterministically generated[1].

This project is based on ultra stable femtosecond mode locked laser (∼ 30 fs pulses, repetition rate of 150 MHz). We first apply the quantum optics tools to give a modal description of classical femtosecond lasers, shining new light on laser dynamics[2]. This study will be pursued and applied to other type of lasers, using further developments achieved in a quantum context. This part of the project is supported by an ANR-DGA project in collaboration with Thales and Laboratoire Aimé Coton.

In order to develop quantum complex network, we use this laser to pump a non-linear crystal. Each pump pulse generates a couple of entangled pulses in two separate spatial channels. While the two will maintain the spectral multi-mode decomposition that can already be arranged as a quantum network, one of the two channels will be delayed in the temporal domain by the time between two consecutive pulses, before being mixed with the other channel on a 50:50 beam-splitter. This will create a dual-rail temporal structure characterized by non-trivial entanglement, which can involve up to 106 temporal-modes.   The interplay between the spectral and the temporal structure of entanglement connections will be used for generating quantum networks[3] with more elaborated geometry involving community structures. Optimization of quantum information protocols and quantum transport phenomena will be studied. Beyond the already identified quantum strategies involving multi-mode quantum states, the variety of experimental implementations opens new fundamental questions on how to describe the quantum nature of a large multiple system and which kind of advantages can be obtained from these resources.

Internship project

We specifically propose an internship on the detection, at the quantum level, of single pulses with a 150MHz repetition rate. The general aim is being able, in real time, to extract the multimode quantum structure in time and frequency of both the classical and quantum sources available.

  • [1]      J. Roslund, R. M. De Araujo, S. Jiang, and C. Fabre, Nature Photonics 8, 109 (2014).
  • [2]      R. Schmeissner, J. Roslund, C. Fabre, and N. Treps, Phys Rev Lett 113, 263906 (2014).
  • [3]      J. Nokkala, F. Galve, R. Zambrini, S. Maniscalco, and J. Piilo, Sci. Rep. 6, 26861 (2016).

Interested candidates should contact Nicolas Treps (, Claude Fabre ( or Valentina Parigi (
For more details, please check our website:

Experimental internship.
Duration: 3 to 6 months. Possible PhD.