Breakthrough in quest to control light to develop next-generation quantum sensing and computing


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Scientists have made a crucial new breakthrough in the quest to control light to develop the next generation of quantum sensing and computers.

The team of researchers, including Dr. Oleksandr Kyriienko of the University of Exeter, has shown that the control of light can be achieved by inducing and measuring a nonlinear phase shift to a single polariton level.

Polaritones are hybrid particles that combine properties of light and matter. They arise in optical structures at strong light-matter coupling, where photons hybridize with underlying particles in the materials – quantum well excitons (bound electron-hole pairs).

The new research, led by the experimental group of Prof. D. Krizhanovskii of the University of Sheffield, has observed that an interaction between polaritons in micropillars leads to a cross-phase modulation between modes of different polarization.

The phase change is significant even in the presence of (on average) a single polariton, and can be further magnified in structures with stronger confinement of light. This provides the opportunity for quantum polaritonic effects that can be used for quantum detection and processing.

Theoretical analysis, led by Dr. Oleksandr Kyriienko, shows that the observed phase shift of a single polariton can be further magnified, and that cascading micropillars provide a path to polaritonic quantum gates.

In turn, quantum effects with weak beams can help detect chemicals, gas leakage and perform calculations at a significantly faster speed.

The research is published by Nature photonics

dr. Kyriienko says that “the experimental results reveal that” quantum effects can be measured at a single polariton level in a single micropillar. From a theoretical point of view, it is important to increase phase shifts and develop the system into an optically controlled phase gate. We will definitely see more efforts to build quantum polaritonic lattices as a quantum technology platform.”

Polaritons have proven to be an excellent platform for: nonlinear opticswhere particles have increased coherence due to the cavity field and highly nonlinear due to exciton-exciton scattering.

Previously, polaritonic experiments led to observation of polaritonic Bose-Einstein condensation and various macroscopic nonlinear effects, including the formation of solitons and vortices. However, the observation of quantum polaritonic effects in the low occupancy limit remains uncharted territory.

The study shows that polaritons can maintain nonlinearity and coherence in extremely small occupations. This leads to a search for polaritonic systems that can further amplify the quantum effects and act as quantum devices.

dr. Paul Walker, the study’s corresponding author, explains that they used “high-quality micropillars from” gallium arsenide provided by collaborators of the University of Paris Saclay, France. These pillars limit forms of different polarization that are close to each other in energy. By pumping light into one of the modes (fundamental), we examine a signal sent to another (higher energy) mode and see that the presence of a weak (single photon) pulse leads to polarization rotation. This can be seen as a controlled phase rotation.”

The senior author of the study Prof. Krizhanovskii concludes that “in the presented experiment we have taken a first step towards single-polariton Effects. There is certainly room for improvement. In fact, by using voids of smaller dimensions and optimizing the structure, we expect that the phase shift orders of magnitude will increase. This will establish the state-of-the-art for future polaritonic chips.”

Reinforcing polaritonic nonlinearity with a mechanism to create polaron polaritons

More information:
Tintu Kuriakose et al, Low-photon all-optical phase rotation in a quantum well micropillar cavity, Nature photonics (2022). DOI: 10.1038/s41566-022-01019-6

Quote: Breakthrough in Quest to Control Light to Develop Next Generation Quantum Detection and Computing (2022, June 20) retrieved June 20, 2022 from quantum.html

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