Ultrafast frequency combs have found tremendous utility as precision instruments in domains ranging from frequency metrology, optical clocks, broadband spectroscopy, and absolute distance measurement. This sensitivity originates from the fact that a comb carries a huge number of co- propagating, coherently-locked frequency modes and ultrafast optics with coherent control techniques became a flourishing field over the last decades. Likewise, exploiting the quantum features of light has enabled remarkable progress for the experimental exploration of fundamental physics and has been central to the establishment of the fields of quantum communication and quantum metrology. The global objective of this research project is to bring together these two vibrant fields with the goal of exploring new capabilities that arise from the interplay of the quantum properties of light at extreme timescales and over extremely broad spectra.

The quantum optics group of Laboratoire Kastler Brossel has developed two new experimental setups along these lines. One is specifically designed for quantum information processing with optical frequency combs. Benefiting from the naturally multimode character of such a laser source, and using techniques imported from coherent control, in particular ultrafast pulse shaping, we could demonstrate the intrinsic nature of light delivered by a synchronously pumped optical parametric oscillator [1]. That work triggered many theoretical studies, as this system is one of the most promising one for measurement based quantum computing [2]. The objective is now to obtain a source which is truly scalable and fully addressable, using in loop pulse shaping for pump optimization, and multipixel homodyne detection for the simultaneous detection of all the modes and the implementation of quantum information protocols [3,4].

Our second experimental setup, started with an ERC starting grant, is oriented towards quantum metrology [5-7]. In particular, we could demonstrate how concepts imported from quantum optics could allow space-time positioning with unprecedented sensitivity. One of the next objectives of this experiment will be to introduce non-classical states to study its influence on the Quantum Cramér Rao limit. To that aim, we will develop a completed novel single pass squeezer, that should allow for the generation of high dimension entangled states in the time/frequency domain.

The quantum optics group is offering a two-year post-doctoral position, with possible extension, in order to conduct these experimental projects, with emphasis on the generation of highly multimode non-Gaussian states for measurement based quantum computing. We will explore the possibility to generate new types of non-classical states and perform non-trivial and useful quantum information operations in the continuous variable regime. This project is supported by the French Research Agency (ANR project COMB).

The group is looking for a candidate with a very good experimental background, and if possible strong knowledge on optical frequency combs and pulse shaping. The candidate will be in charge of the full experimental setup, help the PhD students and be associated to all the scientific choices of the group. He or she will also have the possibility to develop the necessary theory to run the experiment and to draw its perspectives. The position would ideally start on the 1st of January 2015, but this can be adapted.

[1] J. Roslund, R. M. de Araújo, S. Jiang, C. Fabre, and N. Treps, “Wavelength-multiplexed quantum networks with ultrafast frequency combs,” Nature Photonics, vol 8, pp. 109–112, Dec. 2013.

[2] R. Raussendorf and H. J. Briegel, “A One-Way Quantum Computer,” Phys Rev Lett, vol. 86, no. 22, pp. 5188–5191, May 2001.

[3] G. Ferrini, J. P. Gazeau, T. Coudreau, C. Fabre, and N. Treps, “Compact Gaussian quantum computation by multi-pixel homodyne detection,” New J Phys, vol. 15, no. 9, p. 093015, Sep. 2013.

[4] G. Ferrini, J. Roslund, F. Arzani, Y. Cai, C. Fabre, and N. Treps, “Optimization strategies in measurement based quantum computation,” arXiv.org, vol. quant-ph. 20-Jul-2014.

[5] P. Jian, O. Pinel, C. Fabre, B. Lamine, and N. Treps, “Real-time displacement measurement immune from atmospheric parameters using optical frequency combs,” Opt Express, vol. 20, no. 24, pp. 27133–27146, 2012.

[6] B. Lamine, C. Fabre, and N. Treps, “Quantum improvement of time transfer between remote clocks,” Phys Rev Lett, vol. 101, no. 12, pp. –, 2008.

[7] R. Schmeissner, V. Thiel, C. Jacquard, C. Fabre, and N. Treps, “Analysis and filtering of phase noise in an optical frequency comb at the quantum limit to improve timing measurements,” Opt Lett, vol. 39, no. 12, pp. 3603–3606, 2014.