Electron spin qubits in microwave cavities represent a promising foundation for developing quantum computing hardware. Electron spin states have high coherence times compared to gate interaction time scales, and photon coupling allows for long-distance interaction between qubits. The strong spin-photon coupling regime can be realized via the dipole interaction, as Petta et al. [1] demonstrated by placing an electron in a double quantum dot (DQD) with a magnetic field gradient inside a microwave cavity. These studies later included two DQDs inside the cavity to demonstrate long-range spin-spin interactions [2]. Input-output theory describes the system's behavior when driven by an external field and determines the internal qubit states from the transmission amplitude of the output field [3]. The scaling strategy for this system that has been considered thus far by others has involved placing multiple qubits inside of a single cavity. As an alternative setup, we analyze results from a model of a double DQD qubit system consisting of two cavities, each containing one qubit, coupled via a capacitive coupler that allows for single photon exchange. In analogy with previous works, we utilize input-output theory to obtain transmission amplitudes and discuss the various regimes determined by tuning different parameters

Quantum dot circuits (qd) in a circuit cavity quantum electrodynamics (cqed) architecture. the interest of such hybrid systems lies in the light-matter interaction that occurs between the cavity microwave photons and the electrons of the qd. in this thesis work, carbon nanotubes have been chosen as the material for the qds. indeed, it is possible to observe various electronic transport regimes in such systems (fabry-perot, coulomb blockade and kondo). their versatility is also a keypoint as it is possible to contact them with various type of metal electrodes (normal, superconductor, ferromagnetic metal). the experimental realization of such devices has the project of this thesis was to experimentally realize the implementation of shown an electron-photon coupling of the order of 100mhz, comparable to standard cqed couplings. this coupling is tunable by purely electric control. finally, wehave demonstrated the distant interaction between two qds, separated by 80μm, via the microwave cavity photons. these results shows that these devices can be used for manipulating the quantum information as well as for simulate on-chip condensed matter situations. we have therefore been able to measure the quantum capacitance of the qds, and in particular in the kondo regime. we have also simulated the electron-phonon polaronic shift in the case of the distant interaction between the two qds.

Understanding, controlling and, more importantly, enhancing the interaction between light (photons) and spin waves (magnons) can be, among others, a step towards the realization of magnon-mediated microwave-to-optical transducers for quantum computing applications or hybrid solid-state spintronic-photonic interconnections. In this respect, the development of novel composite multifunctional micro/nanostructures — so-called optomagnonic — which simultaneously control optical and spin waves and enhance their interaction, is particularly attractive.This book constitutes a collective work, comprising seven chapters from leading researchers in the field of optomagnonics and related areas. Apart from exciting recent developments, it provides the necessary fundamental knowledge in an explanatory manner and, therefore, it is accessible to non-experts. It is suitable for PhD students, post-docs, and researchers who are willing to get engaged in optomagnonics, while selected parts could also serve as lecture material for advanced courses. With increasing demand for miniaturized optomagnonic devices, this book will be an important resource to researchers working on optomagnonics, magneto-optics, spintronics, as well as on hybrid micro/nano devices for information processing.

The counter-intuitive aspects of quantum physics have been long illustrated by thought experiments, from Einstein's photon box to Schrödinger's cat. These experiments have now become real, with single particles - electrons, atoms, or photons - directly unveiling the strange features of the quantum. State superpositions, entanglement and complementarity define a novel quantum logic which can be harnessed for information processing, raising great hopes for applications. This book describes a class of such thought experiments made real. Juggling with atoms and photons confined in cavities, ions or cold atoms in traps, is here an incentive to shed a new light on the basic concepts of quantum physics. Measurement processes and decoherence at the quantum-classical boundary are highlighted. This volume, which combines theory and experiments, will be of interest to students in quantum physics, teachers seeking illustrations for their lectures and new problem sets, researchers in quantum optics and quantum information.

This work describes theoretical and experimental advances towards the realization of a hybrid quantum processor in which the collective degrees of freedom of an ensemble of spins in a crystal are used as a multi-qubit register for superconducting qubits. A memory protocol made of write, read and reset operations is first presented, followed by the demonstration of building blocks of its implementation with NV center spins in diamond. Qubit states are written by resonant absorption of a microwave photon in the spin ensemble and read out of the memory on-demand by applying Hahn echo refocusing techniques to the spins. The reset step is implemented in between two successive write-read sequences using optical repumping of the spins.

This comprehensive textbook on the rapidly advancing field introduces readers to the fundamental concepts of information theory and quantum entanglement, taking into account the current state of research and development. It thus covers all current concepts in quantum computing, both theoretical and experimental, before moving on to the latest implementations of quantum computing and communication protocols. It contains problems and exercises and is therefore ideally suited for students and lecturers in physics and informatics, as well as experimental and theoretical physicists in academia and industry who work in the field of quantum information processing. The second edition incorporates important recent developments such as quantum metrology, quantum correlations beyond entanglement, and advances in quantum computing with solid state devices.

Written by two well-known researchers in the field, this useful reference takes an applied approach to high frequency processes including oscillations and waves in ferromagnets, antiferromagnets, and ferrimagnets. Problems evaluated include ferromagnetic and antiferromagnetic resonances, spin waves, nonlinear processes, and high frequency manifestations of interactions between the magnetic system and other systems of magnetically ordered substances as elastic waves and charge carriers. Unlike previous monographs on this subject, which are highly theoretical and written for very advanced readers, this book requires only an average college background in mathematics and experimental physics. It will be a valuable addition to the library of engineers and scientists in research and development for communications applications, and scientists interested in nonlinear magnetic phenomena. It also serves as an excellent introduction to the topic for newcomers in the field. Magnetization Oscillations and Waves not only presents results but also shows readers how to obtain them; most formulas are derived with so many details that readers can reproduce them. The book includes many summaries and tables and detailed references to significant work in the area by European researchers.