The information science and technology revolution of the 20th century exploited only a tiny fraction of the concepts introduced by quantum mechanics. For the past two decades, a second technological revolution has been in the making, based on subtle and fragile concepts such as quantum entanglement and superposition. The ability to manipulate quantum systems, known as " elementary ", is at the heart of these developments, opening the way to a wide range of applications : computers capable of outperforming today's supercomputers, communication networks secured by quantum laws, or sensors measuring gravity and magnetic fields with unprecedented precision.
Although many systems are being explored (atoms, ions, quantum boxes, superconducting circuits, colored defects, etc.), a solid understanding of these advances can be gained from simple model systems : the single spin and the photon, making it possible to describe qubits known respectively as " stationary " and " flying ". We will also look at the phenomena at the heart of decoherence, a notion that describes the fragility of the quantum states produced, and which represents the major challenge common to all these technological developments. This will illustrate the diversity of the physical systems explored and their specific features.
We will then present a few technological developments representative of this second revolution : single and entangled photon sources, the first prototypes of quantum computers using photons, ions or atoms. We'll also look at the role of vibrations in quantum technologies, sometimes a source of decoherence, but also at the heart of new sensor technologies. Finally, we'll be looking at quantum interfaces and quantum memories, which provide the link between stationary qubits and flywheels, key components in a wide range of applications. The seminar program will illustrate and broaden the concepts by presenting the most recent advances in the field.