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All optical detectors to date annihilate photons upon detection, thus excluding repeated measurements. Here, we demonstrate a robust photon detection scheme that does not rely on absorption. Instead, an incoming photon is reflected from an optical resonator containing a single atom prepared in a superposition of two states. The reflection toggles the(More)
A major challenge for a scalable quantum computing architecture is the faithful transfer of information from one node to another. We report on the realization of an atom-photon quantum interface based on an optical cavity, using it to entangle a single atom with a single photon and then to map the quantum state of the atom onto a second single photon. The(More)
Quantum networks are distributed quantum many-body systems with tailored topology and controlled information exchange. They are the backbone of distributed quantum computing architectures and quantum communication. Here we present a prototype of such a quantum network based on single atoms embedded in optical cavities. We show that atom-cavity systems form(More)
Optical nonlinearities offer unique possibilities for the control of light with light. A prominent example is electromagnetically induced transparency (EIT), where the transmission of a probe beam through an optically dense medium is manipulated by means of a control beam. Scaling such experiments into the quantum domain with one (or just a few) particles(More)
Characterizations of low-loss mirrors by measurements of cavity-decay time and of cavity finesse are reported hear 850 nm. The lowest observed mirror loss is 1.6 x 10-6 (transmission plus absorption and scatter), which corresponds to a reflectivity of 0.9999984 and to a cavity finesse of 1.9 x 106. High-reflectivity mirrors with small scatter and absorption(More)
The interference of two independent single-pho-ton pulses impinging on a beam splitter is analysed in a gen-eralised time-resolved manner. Different aspects of the phenomenon are elaborated using different representations of the single-photon wave packets, like the decomposition into single frequency field modes or spatio-temporal modes matching the(More)
The steady increase in control over individual quantum systems supports the promotion of a quantum technology that could provide functionalities beyond those of any classical device. Two particularly promising applications have been explored during the past decade: photon-based quantum communication, which guarantees unbreakable encryption but which still(More)
Atomic quantum gases in the strong-correlation regime offer unique possibilities to explore a variety of many-body quantum phenomena. Reaching this regime has usually required both strong elastic and weak inelastic interactions because the latter produce losses. We show that strong inelastic collisions can actually inhibit particle losses and drive a system(More)
A novel setup for investigations in cavity quantum electrodynamics is described, which combines an optical microcavity Ž 5. 85 finesse 4.3 = 10 with an atomic Rb fountain, allowing full control over density and velocity of atoms entering the optical cavity. To demonstrate this point we study the temporal width of the transmission drops if slow single atoms(More)
All conventional methods to laser-cool atoms rely on repeated cycles of optical pumping and spontaneous emission of a photon by the atom. Spontaneous emission in a random direction provides the dissipative mechanism required to remove entropy from the atom. However, alternative cooling methods have been proposed for a single atom strongly coupled to a(More)