When designing quantum devices, it is essential to carefully select the operating principles and particles that will be used. However, this is difficult due to the inherent trade-off that exists between the lifetime, or ‘coherence’, of particles and the strength of their interactions. For example, photons are very coherent but interact weakly, whereas excitons and other forms of excitations in matter interact strongly but are weakly coherent.
In contrast, polaritons are hybrid particles made from light and matter that offer a solution to this trade-off in certain applications. In an article we published in Physical Review Letters in 2010, we theoretically predicted a mechanism by which strongly confined polaritons could generate squeezed light; that is, a continuous stream of photons with highly supressed quantum fluctuations.
We then collaborated with experimentalists from Centre National de la Recherche Scientifique (CNRS) and Université Pierre et Marie Curie, France, to make our predictions a reality. To this end, we employed a semiconductor microstructure with a tailored pillar shape. This device separated the energy levels of the possible quantum states of polaritons generated using a laser light. In turn, this separated energy levels suppressed the effects of noise injection to a quantum state from the other quantum states that were not excited by the laser light. The results of this collaboration were published in Nature Communications in 2014.
Our findings could pave the way for new techniques to generate and exploit squeezed light, which is important for upcoming technology in the fields of quantum computing, quantum communications, and quantum sensing. Most notably, because the power range used in the experiments was about a few milliwatts, quantum devices based on the studied premise could be integrated in semiconductor platforms.
Overall, these studies are a demonstration of what’s possible when theoretical and experimental physicists team up. Although such collaborations are not so frequent in the recent studies of physics, they are essential to advance the field of quantum mechanics and related technological applications.
Motoaki Bamba, Simon Pigeon, and Cristiano Ciuti
“Quantum Squeezing Generation versus Photon Localization in a Disordered Planar Microcavity”
Physical Review Letters 104, 213604 (2010)
Thomas Boulier, Motoaki Bamba, Albert Amo, Claire Adrados, Lemaitre Lemaitre, Elisabeth Galopin, Isabelle Sagnes, Jacqueline Bloch, Cristiano Ciuti, Elisabeth Giacobino, and Albert Bramati
“Polariton-generated intensity squeezing in semiconductor micropillars”
Nature Communications 5, 3260 (2014)