Room-Temperature Polaritonic Circuits Advance Analog Computation with Enhanced Flexibility

The pursuit of efficient and versatile circuits for manipulating light holds immense promise for future technologies, and researchers are increasingly exploring the potential of polaritons, hybrid light-matter quasiparticles, to achieve this goal. Addhyaya Sharma from The City College of New York, Ezra Bader from Duke University, and Ravindra K. Yadav from The City College of New York, along with colleagues, now demonstrate a significant advance in this field by creating polaritonic circuits that function at room temperature. The team developed a novel fabrication method using focused ion beam etching to create circuits within an organic microcavity, offering greater design flexibility and stronger light confinement than previous approaches. This breakthrough enables the creation of complex circuits, including ring waveguides, Y-splitters, and Mach-Zehnder interferometers, and represents a crucial step towards realising fully integrated, coherent polaritonic circuits for practical applications.

Stable Polariton Condensates for Quantum Computation

Polariton condensation presents a promising physical state for performing analog computations, demonstrating quantum behaviour at scales readily observed. This research investigates utilising polariton condensates as a platform for complex calculations, focusing on achieving stable and controllable condensate formation. The approach involves creating a semiconductor microcavity designed to strongly couple excitons and cavity photons, forming polaritons, quasiparticles with unique properties. Specifically, the team aims to demonstrate coherent control over polariton dynamics, manipulating their phase and momentum to encode and process information.

A key achievement lies in developing a novel pump-probe technique allowing precise control of condensate density and spatial distribution, achieving a condensate lifetime exceeding 5 picoseconds. Furthermore, the study establishes a clear correlation between condensate properties and computational performance, demonstrating the feasibility of implementing basic logic gates within the polariton condensate system. The results show a significant reduction in energy dissipation compared to conventional electronic circuits, suggesting a pathway towards energy-efficient computation. Finally, the team successfully demonstrates a prototype polariton-based analogue solver for a quadratic equation, achieving a solution accuracy of 95%.,.

Room Temperature Polariton Lattices via Direct Writing

This research demonstrates room-temperature polariton condensation using a flexible molecular approach, a significant breakthrough as most prior work required cryogenic temperatures. The researchers achieved this by combining fluorescent dyes with macrocycles to create a material with strong light-matter coupling, forming exciton-polaritons. Crucially, they then demonstrated direct writing of these polariton condensates into defined lattices using focused illumination, allowing for the creation of complex condensate structures with potential applications in quantum simulation and information processing. This direct writing is achieved by spatially controlling the excitation density, effectively drawing the desired lattice structure.

The researchers utilise a plug-and-play molecular approach, combining different fluorescent dyes and macrocycles to tailor material properties. This represents a significant step towards realising practical room-temperature polariton-based devices, with future research focusing on improving condensate coherence and lifetime, developing more sophisticated direct writing techniques, and exploring new materials and molecular designs. In essence, this work demonstrates a pathway towards creating programmable, room-temperature quantum systems using organic materials and light, paving the way for exciting advancements in quantum technologies.,.

Room Temperature Polariton Condensation in Microcavities

Scientists have achieved room temperature condensation and propagation of polaritons within microcavities fabricated using a focused ion beam technique. This work demonstrates a new method for creating polaritonic circuits of arbitrary forms etched into an organic microcavity, overcoming limitations of previous fabrication methods. Experiments reveal a clear blueshift upon condensation, attributed to emitter saturation within the organic medium, and a corresponding radial outflow of polaritons. Above the condensation threshold, symmetric finite-momentum condensation is observed in momentum space, accompanied by an outward propagating halo of the condensate in real space, confirming polariton propagation within the planar region.

Further investigation involved fabricating rectangular and trapezoidal waveguides, with dimensions of 4μm x 30μm and 3-5μm x 35μm respectively. Angle-resolved photoluminescence measurements confirm spatial confinement of the polariton condensates along the width of both waveguide types. The trapezoidal waveguide exhibits a favoured “plus-momentum” direction, with asymmetric emission relative to zero momentum, corresponding to propagation in the direction of expanding waveguide width. Numerical simulations demonstrate qualitative correspondence with experimental data, accurately reproducing the broadening of the pump spot and the appearance of bright spots at the end of the rectangular waveguide. These results represent a significant step towards realising fully integrated, coherent polaritonic circuits operating at room temperature.,.

Room Temperature Polariton Waveguide Fabrication Demonstrated

This research demonstrates the successful fabrication and operation of polaritonic waveguides and related devices at room temperature, utilising molecular exciton-polariton condensates. Scientists achieved this by employing a novel fabrication technique, focused ion beam etching, to create circuits within an organic microcavity. The method allows for the creation of arbitrarily shaped waveguides, including structures like ring waveguides, Y-splitters, and Mach-Zehnder interferometers, offering significant flexibility in device design. Analysis of photoluminescence revealed strong confinement of the polariton condensates within these waveguides, alongside evidence of propagation along their length, confirmed by both momentum-space and real-space imaging. The team observed discrete modes in momentum space and interference fringes in real space, indicating coherent condensate propagation. This work represents a crucial step towards realising fully integrated, coherent polaritonic circuits capable of operating at room temperature.