Phase Fluctuations In Microcavity Exciton Polariton Condensation

In a homogeneous two-dimensional system at non-zero temperature, although there can be no ordering of infinite range, an ordered superfluid phase is expected to occur for a Bose liquid. Theory predicts that, in this phase, the correlation function decays with distance as a power law, and quantum vortices are bound to antivortices to form molecular-like pairs. We study the relevance of this theory to microcavity exciton polaritons. These are two-dimensional bosonic quasiparticles formed as a superposition of a microcavity photon and a semiconductor quantum well exciton, and have been shown to condense at high enough densities. Because of the short lifetime, equilibrium is not established, but we instead probe the steady state of the system, in which particles are continuously injected from a pumping reservoir. We employ a Michelson interferometer setup to measure the first order spatial correlation function of such a condensate. The gaussian form of the short-distance decay allows us to define an effective thermal de Broglie wavelength, although the system is not in thermal equilibrium. The long-distance decay is measured to be a power law with an exponent in the range 0.9-1.2, larger than is possible in equilibrium. Our non-equilibrium theory suggests that this can be attributed to laser pumping noise. We also present our observation of a single vortex-antivortex pair in a condensate of the appropriate size. Pairs are generated due to pumping noise, and are formed sequentially at the same point due to the inhomogeneous pumping spot profile. They are revealed in the time-integrated phase maps acquired using Michelson interferometry. Our results suggest that vortex-antivortex pairs can be created in a two-dimensional condensate without rotation or stirring. The observed correlated motion of a vortex and antivortex imply that vortex-antivortex pairs do not dissociate, which is consistent with the measured power law decay of the spatial correlation function. These two experiments uniquely describe the condensate phase fluctuations and provide stringent tests to theories of nonequilibrium condensation. They also highlight the exciton polariton condensate as a very well characterized system showing mesoscopic coherence and deepen our understanding of fundamental two-dimensional bosonic physics. Progress in this field is expected to lead towards long-sought applications such as quantum simulation or low-threshold laser sources.

In the past decade, there has been a burst of new and fascinating physics associated to the unique properties of two-dimensional exciton polaritons, their recent demonstration of condensation under non-equilibrium conditions and all the related quantum phenomena, which have stimulated extensive research work. This monograph summarizes the current state of the art of research on exciton polaritons in microcavities: their interactions, fast dynamics, spin-dependent phenomena, temporal and spatial coherence, condensation under non-equilibrium conditions, related collective quantum phenomena and most advanced applications. The monograph is written by the most active authors who have strongly contributed to the advances in this area. It is of great interests to both physicists approaching this subject for the first time, as well as a wide audience of experts in other disciplines who want to be updated on this fast moving field.

The study of quantum fluids, stimulated by the discovery of superfluidity in liquid helium, has experienced renewed interest after the observation of Bose-Einstein condensation (BEC) in ultra-cold atomic gases and the observation a new type of quantum fluid with specific characteristics derived from its intrinsic out-of-equilibrium nature. The main objective of this book is to take a snapshot of the state-of-the-art of this fast moving field with a special emphasis on the hot topics and new trends. Bringing together the most active specialists of the two areas (atomic and polaritonic quantum fluids), we expect that this book will facilitate the exchange and the collaboration between these two communities working on subjects with very strong analogies.

Semiconductor quantum science and technology is exploring the exciting and emerging prospects of integrating quantum functionality on semiconductor platforms to convert current information technology into quantum information technology. The past twenty years have led to incredible advances in this field. This book brings together the leading scientists who present the main achievements and challenges by reviewing and motivating the state-of-the-art at a tutorial level. The key challenges include creating quantum-light sources, quantum information processing via strong light-matter interaction, discovering new quantum materials as well as quasiparticles, and determining new quantum spectroscopic methodologies for superior control of quantum phenomena. As an important step, integration of these solutions on a semiconductor chip is discussed, and outlook for the future of semiconductor quantum science and technology is given. Leading experts present their vision on semiconductor quantum science and technology All aspects needed to realize semiconductor quantum science and technology are explained Quantum semiconductors from overviewed a tutorial introduction to the state-of-the-art

This reference book explains the fundamentals of Bose Einstein Condensation (BEC) in excitons and polaritons. It presents five chapters exploring fundamental concepts and recent developments on the subject. Starting with a historical overview of BEC, the book progresses into the origins and behaviors of excitons and polaritons. Chapters also cover the unique thermalization and relaxation kinetics of excitons, and the distinctive features of polaritons, such as lasing, superfluidity, and quantized vortices. The chapters dedicated to BEC in excitons and polaritons detail experimental techniques, theoretical modeling, recent advancements, and practical applications in a simplified way for beginners. This book serves as a resource for researchers, physicists, and students interested in the phenomena of BEC, providing insights into both the theoretical foundations and the practical implications of excitons and polaritons.

Electron and photon confinement in semiconductor nanostructures is one of the most active areas in solid state research. Written by leading experts in solid state physics, this book provides both a comprehensive review as well as a excellent introduction to fundamental and applied aspects of light-matter coupling in microcavities. Topics covered include parametric amplification and polariton liquids, quantum fluid and non-linear dynamical effects and parametric instabilities, polariton squeezing, Bose-Einstein condensation of microcavity polaritons, spin dynamics of exciton-polaritons, polariton correlation produced by parametric scattering, progress in III-nitride distributed Bragg reflectors using AlInN/GaN materials, high efficiency planar MCLEDs, exciton-polaritons and nanoscale cavities in photonic crystals, and MBE growth of high finesse microcavities.

Covering general theoretical concepts and the research to date, this book demonstrates that Bose-Einstein condensation is a truly universal phenomenon.

The fundamental concept of quantum coherence plays a central role in quantum physics, cutting across disciplines of quantum optics, atomic and condensed matter physics. Quantum coherence represents a universal property of the quantum s- tems that applies both to light and matter thereby tying together materials and p- nomena. Moreover, the optical coherence can be transferred to the medium through the light-matter interactions. Since the early days of quantum mechanics there has been a desire to control dynamics of quantum systems. The generation and c- trol of quantum coherence in matter by optical means, in particular, represents a viable way to achieve this longstanding goal and semiconductor nanostructures are the most promising candidates for controllable quantum systems. Optical generation and control of coherent light-matter states in semiconductor quantum nanostructures is precisely the scope of the present book. Recently, there has been a great deal of interest in the subject of quantum coh- ence. We are currently witnessing parallel growth of activities in different physical systems that are all built around the central concept of manipulation of quantum coherence. The burgeoning activities in solid-state systems, and semiconductors in particular, have been strongly driven by the unprecedented control of coherence that previously has been demonstrated in quantum optics of atoms and molecules, and is now taking advantage of the remarkable advances in semiconductor fabrication technologies. A recent impetus to exploit the coherent quantum phenomena comes from the emergence of the quantum information paradigm.