This book reviews progress towards quantum simulators based on photonic and hybrid light-matter systems, covering theoretical proposals and recent experimental work. Quantum simulators are specially designed quantum computers. Their main aim is to simulate and understand complex and inaccessible quantum many-body phenomena found or predicted in condensed matter physics, materials science and exotic quantum field theories. Applications will include the engineering of smart materials, robust optical or electronic circuits, deciphering quantum chemistry and even the design of drugs. Technological developments in the fields of interfacing light and matter, especially in many-body quantum optics, have motivated recent proposals for quantum simulators based on strongly correlated photons and polaritons generated in hybrid light-matter systems. The latter have complementary strengths to cold atom and ion based simulators and they can probe for example out of equilibrium phenomena in a natural driven-dissipative setting. This book covers some of the most important works in this area reviewing the proposal for Mott transitions and Luttinger liquid physics with light, to simulating interacting relativistic theories, topological insulators and gauge field physics. The stage of the field now is at a point where on top of the numerous theory proposals; experiments are also reported. Connecting to the theory proposals presented in the chapters, the main experimental quantum technology platforms developed from groups worldwide to realize photonic and polaritonic simulators in the laboratory are also discussed. These include coupled microwave resonator arrays in superconducting circuits, semiconductor based polariton systems, and integrated quantum photonic chips. This is the first book dedicated to photonic approaches to quantum simulation, reviewing the fundamentals for the researcher new to the field, and providing a complete reference for the graduate student starting or already undergoing PhD studies in this area.

In recent years, the development of various platforms for quantum simulation made it possible to study many-body systems under controlled conditions. Of particular interest are one-dimensional systems, known to exhibit some unique properties compared to their higher-dimensional counterparts. One of the current promising platforms for simulations of one-dimensional systems are Rydberg dark polaritons, quasiparticles of a photon-matter hybrid character emerging in the context of electromagnetically induced transparency (EIT) coupled with Rydberg atoms. These polaritons are long-lived (owing to the properties of EIT) and inherit interaction properties from the huge polarizability of Rydberg atoms, both attractive features in the context of simulations. We herein construct an experimental proposal for realizing one-dimensional physics through Rydberg dark polaritons. By using a stationary-light scheme, a sequence of steps allows a laser pulse incident on a transversally trapped gas of Rydberg atoms to yield a stationary pulse of weakly interacting polaritons. Within the stationarity regime, the lasers are further tuned to adjust the interaction effective one-dimensional scattering length through a Feshbach-like resonance to create a Tonks-Girardeau-type gas of polaritons. Signatures of non-trivial correlations can then experimentally probed by retrieving the photons through a subsequent adjustment of the laser strengths. Realizing this proposal would be a landmark achievement in the fields of many-body simulations and Rydberg physics.

The last century has been characterized by the development of information theory and the consequent transformative impact of new technologies on societies around the world. It seems likely that the tremendous progress in nanoscience – the ability to manipulate microscopic systems at the level of a single atom – and the emergence of quantum information science, will be the key components of the next revolution; that of the new quantum technologies. Indeed, the ability to manipulate and control quantum systems has already found a variety of potential applications, ranging from the development of molecular nanoscale machines which exploit quantum coherence for their functioning, to metrological schemes where quantum effects are used to enhance the accuracy of measurement and detection systems to achieve higher statistical precision than is possible using purely classical approaches. This book presents the proceedings of the Enrico Fermi Summer School on Quantum Simulators (Course 198) held in Varenna, Italy, 22-27 July 2016. Topics covered included: cold atoms in optical lattices; trapped ions; solid state implementations; quantum many-body physics; quantum photonics; hybrid quantum systems; and transport phenomena. The book will be of interest to all those whose work is connected to the rapidly growing field of quantum technologies.

This book introduces the wider field of functional nanomaterials sciences, with a strong emphasis on semiconductor photonics. Whether you are studying photonic quantum devices or just interested in semiconductor nanomaterials and their benefits for optoelectronic applications, this book offers you a pedagogical overview of the relevant subjects along with topical reviews. The book discusses different yet complementary studies in the context of ongoing international research efforts, delivering examples from both fundamental and applied research to a broad readership. In addition, a hand-full of useful optical techniques for the characterization of semiconductor quantum structures and materials are addressed. Moreover, nanostructuring methods for the production of low-dimensional systems, which exhibit advantageous properties predominantly due to quantum effects, are summarized. Science and engineering professionals in the interdisciplinary domains of nanotechnology, photonics, materials sciences, and quantum physics can familiarize themselves with selected highlights with eyes towards photonic applications in the fields of two-dimensional materials research, light–matter interactions, and quantum technologies.

With the launch of the Quantum Technology Flagship Programme by the European Commission, developments in the realization of new technologies based on quantum physics have been recognized as a priority. These are important for cryptographic techniques for telecommunications security, new computing hardware that can solve problems so far inaccessible even to the latest generation of supercomputers, and precision standards and sensors with important applications ranging from materials science to medical diagnostics. This book presents a collection of lectures from the International School of Physics Enrico Fermi on Nanoscale Quantum Optics, held in Varenna, Italy, from 23 – 28 July 2018. The course was attended by 60 students, researchers and lecturers, and provided an opportunity to train a new generation of scientists on topics that promise great innovations in science and technology. Included here are 9 lectures and seminars and 3 poster contributions from the school. Subjects covered include: basic concepts for quantum optics and quantum technologies; materials for quantum nanophotonics; quantum optics and non-classical light generation; creating quantum correlations between quantum-dot spins; platforms for telecom-entangled photon sources; nanoscale sensing and quantum coherence; and nano-optomechanics, among others. The book offers a valuable overview of the state-of-the-art and current trends in nanoscale quantum optics. It will be invaluable for all those with an interest in this subject.

An exciting frontier in quantum information science is the creation and manipulation of bottom-up quantum systems that are built and controlled one by one. For the past 30 years, we have witnessed signi cant progresses in harnessing strong atom- eld interactions for critical applications in quantum computation, communication, simulation, and metrology. By extension, we can envisage a quantum network consisting of material nodes coupled together with in nite-dimensional bosonic quantum channels. In this context, there has been active research worldwide to achieve quantum optical circuits, for which single atoms are wired by freely-propagating single photons through the circuit elements. For all these systems, the system-size expansion with atoms and photons results in a fundamental pathologic scaling that linearizes the very atom- eld interaction, and signi cantly limits the degree of non-classicality and entanglement in analog atom- eld quantum systems for atom number N 1. The long-term motivation of this MSc thesis is (i) to discover new physical mechanisms that extend the inherent scaling behavior of atom- eld interactions and (ii) to develop quantum optics toolkits that design dynamical gauge structures for the realization of lattice-gauge-theoretic quantum network and the synthesis of novel quantum optically gauged materials. The basic premise is to achieve the strong coupling regime for a quantum many-body material system interacting with the quantized elds of an optical cavity. Our laboratory e ort can be described as the march towards \many-body QED," where optical elds acquire some properties of the material interactions that constrain their dynamical processes, as with quantum eld theories. While such an e ort currently do not exist elsewhere, we are convicted that our work will become an essential endeavor to enable cavity quantum electrodynamics (QED) in the bona- de regime of quantum many-body physics in this entanglement frontier. In this context, I describe an example in Chapter 2 that utilizes strong RydbergRydberg interactions to design dynamical gauge structures for the quantum square ice models. Quantum uctuations driven by cavity-mediated in nite-range interaction stabilize the quantum-gauged system into a long-range entangled quantum spin liquid that may be detected through the time-ordered photoelectric statistics for photons leaking out of the cavity. Fractionalized \spinon" and \vison" excitations can be manipulated for topological quantum computation, and the emergent photons of arti cial QED in our lattice gauge theoretic system can be directly measured and studied. The laboratory challenge towards strongly coupled cavity Rydberg polaritons encompasses three daunting research milestones that push the technological boundaries beyond of the state-of-the-arts. In Chapter 3, I discuss our extreme-high-vacuum chamber (XHV) cluster system that allows the world's lowest operating vacuum environment P ' 10 Torr for an ultracold AMO experiment with long background-limited trap lifetimes. In Chapter 4, I discuss our ultrastable laser systems stabilized to the ultra-low-expansion optical cavities. Coupled with a scalable eld-programmable-gate-array (FPGA) digitalanalog control system, we can manipulate arbitrarily the phase-amplitude relationship of several dozens of laser elds across 300 nm to 1550 nm at mHz precision. In Chapter 5, we discuss the quantum trajectory simulations for manipulating the external degrees of freedom of ultracold atoms with external laser elds. Electrically tunable liquid crystal lens creates a dynamically tunable optical trap to move the ultracold atomic gases over long distance within the ultra-high-vacuum (UHV) chamber system. In Chapter 6, I discuss our collaborative development of two science cavity platforms { the \Rydberg" quantum dot and the many-body QED platforms. An important development was the research into new high-index IBS materials, where we have utilized our low-loss optical mirrors for extending the world's highest cavity nesse F 500k! We discuss the unique challenges of implementing optical cavity QED for Rydberg atoms, which required tremendous degrees of electromagnetic shielding and eld control. Single-crystal Sapphire structure, along with Angstrom-level diamond-turned Ti blade electrodes, is utilized for the eld compensation and extinction by > 60 dB. Single-crystal PZTs on silica V-grooves are utilized for the stabilization of the optical cavity with length uncertainty less than 1=100 of a single nucleon, along with extreme level of vibration isolation in a XHV environment. The capability to perform in-situ RF plasma cleaning allows the regeneration of optical mirrors when coated with a few Cs atoms. Lastly but not the least, we combine single-atom resolution quantum gas microscopy technique with superpixel holographic algorithm to project arbitrary real-time recon gurable di raction-limited optical potential landscapes for the preparation of low-entropy atom arrays.

Polaritonic chemistry is an emergent interdisciplinary field in which the strong interaction of organic molecules with confined electromagnetic field modes is exploited in order to manipulate the chemical structure and reactions of the system. In the regime of strong light-matter coupling the interaction with the electromagnetic vacuum obliges us to redefine the concept of a molecule and consider the hybrid system as a whole. This thesis builds on the foundations of chemistry and quantum electrodynamics in order to provide a theoretical framework to describe these organic light-matter hybrids. By fully embracing the structural complexity of molecules, this theory allows us to employ long-established quantum chemistry methods to understand polaritonic chemistry. This leads to predictions of substantial structural changes in organic molecules and the possibility of significantly influencing chemical reactions both in the excited and ground states of the system.