EAGER: Enabling Quantum Leap: Manipulating polariton entanglement for room-temperature quantum logic

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

Quantum computing offers a tremendous advantage over traditional computing because it exploits quantum mechanical phenomena that can in principle carry out logic tasks much faster and more efficiently than even the best computers at present. Nevertheless, quantum computing is still in its infancy. Quantum computation exploits entanglement - a key peculiarity of quantum particles - where it is fundamentally impossible to distinguish between the properties of two identical particles, regardless of how far they are from each other. Achieving robust entanglement at room temperature remains one of the most important challenges in realizing a quantum computer. The present project overcomes existing fundamental limitations to room-temperature entanglement by designing and fabricating optical devices that produce entangled particles that are hybrids of light and matter, termed polaritons. Entangled polaritons are manipulated and controlled by applying an electrical voltage to the device. Polariton entanglement is designed to be stable over sufficiently long time to perform quantum computing operations at room temperature. In addition to the scientific and technical innovations involved in this research, it serves as a training platform to contribute to the intellectual capital and scientific infrastructure of the US, in which quantum technologies is growing in significance. Technical description: The key objective of this project is to demonstrate a universal quantum gate operating at room temperature, harnessing polariton entanglement in semiconductor microcavities that are designed to be addressable by an external electric field. Exciton polaritons are half-light, half-matter quasiparticles that are produced by strong (non-perturbative) coupling of photons and excitons. Because of their hybrid identity, exciton polaritons promise opportunities for quantum-optical gates by manipulation of entanglement in matter, since matter interactions can evolve the entangled state. An important task is thus to demonstrate the ability to map photon entanglement onto matter in microcavities. The entangled bi-polariton state can be manipulated by an applied electric field to independently control both photon and matter components. By this external control, universal two-qubit quantum gates are tested. Two-dimensional metal-halide hybrid perovskites are chosen as the active material because of their high oscillator strength, high exciton binding energy, and strong multi-exciton interactions. Fabry-Perot microcavities are based on a combination of versatile inorganic-organic hybrid materials that are readily index-tunable via composition and post-deposition procedures, and metal oxides that can be deposited by sol-gel methods. The successful outcome of this EAGER project entails a demonstration of a universal quantum gate, which lays the platform to pursue its implementation in quantum computation. Beyond the primary outcome of demonstrating a universal quantum gate, this endeavor requires innovation in addressable microcavities and thus advances knowledge of materials processing protocols for scalable room-temperature quantum optoelectronics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.