Description
Exciton-polaritons are quasiparticles that arise in semiconductors from the strong coupling between light (microcavity photon fields) and matter (bound electron-hole pairs called excitons). Being bosonic particles, polaritons undergo Bose-Einstein condensation (BEC) - a phase transition wherein a large number of particles collectively occupy the ground state of the system. Since polaritons decay by emitting light of the same energy and momentum, polariton BECs can be used as a source of bright, coherent light.
Being part-matter, the Coulomb interaction between the excitonic component of polaritons results in a nonlinearity that has been predicted to give rise to a variety of effects, such as optical bistability and squeezing. Perhaps the most important of these is the potential for polariton BECs to be used as a deterministic source of bright, non-Gaussian states of light [1]. Such behaviour has not yet been predicted to occur in other platforms and remains a crucial stage in the development of universal, continuous-variable optical quantum computers.
In this work, we present the first phase-sensitive reconstructions of the quantum state of a polariton system. By creating polaritons directly in the ground state with a pump laser of the same energy and momentum, we can use a portion of the pump laser to study the noise statistics of the light emitted by the polariton condensate. Our method enables us to gain direct experimental access to the true nature of polariton systems, setting a new precedent for their characterisation. So far, we have observed the transition from a thermal state to a thermal-squeezed state under increasing pump laser powers. Continued refinements to this setup promise to reveal more intricate details, enabling the potential detection of non-Gaussian states and informing the direction for future experiments.
[1] T. Byrnes et al., Phys. Rev. B 87, 201301(R) (2013)
| I am the presenting author | Yes |
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