Polariton condensates in optical microcavities: from devices to fundamental quantum mechanics
Luis Viña - Universidad Autónoma de Madrid
Jeudi 18/02/2016, 11h00-12h00
Bât. K, Salle R. Lemaire (K223), Institut Néel

Polaritons in semiconductor microcavities offer an incomparable playground to study a great variety of physics, from applied aspects to fundamental quantum mechanical questions.

In the first part of the talk, I discuss the logical operation of an ultrafast exciton polariton transistor switch, all-optically controlled and operated by propagating Bose-Einstein exciton-polariton condensate bullets in a quasi-1D semiconductor microcavity and demonstrate that the overall operation speed of the device is limited to ∼3 GHz [1]. I also show how spin-selective spatial filtering of these propagating condensates can be achieved using a controllable spin-dependent gating

barrier: a non-resonant laser beam provides the source of propagating polaritons, while a second circularly polarized weak beam imprints a spin dependent potential barrier, which gates the polariton flow and generates polariton spin currents [2].

In the second part, I illustrate that the use of optical interferometry in momentum space, avoiding any spatial overlap between two parts of a macroscopic quantum state [3], renders a unique way to address a long-standing question raised by P.W. Anderson: "Do two components of a condensate, which have never seen each other, possess a definitive phase?" [4,5] This issue is related to the superposition principle in quantum mechanics and it is crucial to understand how mutual coherence is acquired.

[1] C. Antón et al., Phys. Rev. B 89, 235312 (2014).

[2] T. Gao et al., Appl. Phys. Lett. 107, 011106 (2015).

[3] C. Antón, et al., Phys. Rev B 90, 081407(R) (2014).

[4] P. W. Anderson, Basic Notions of Condensed Matter Physics (Benjamin, 1984).

[5] L. Pitaevskii and S. Stringari, Phys. Rev. Lett. 83, 4237 (1999).

Contact : Michel BENINI


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