Full observation of single-atom dynamics in cavity QED

We report the use of broadband heterodyne spectroscopy to perform continuous measurement of the interaction energy between one atom and a high-finesse optical cavity, during individual transit events of $\sim 250$ $\mu$s duration. Measurements over a wide range of atom-cavity detunings reveal the transition from resonant to dispersive coupling, via the transfer of atom-induced signals from the amplitude to the phase of light transmitted through the cavity. By suppressing all sources of excess technical noise, we approach a measurement regime in which the broadband photocurrent may be interpreted as a classical record of conditional quantum evolution in the sense of recently developed quantum trajectory theories.Comment: Submitted to Applied Physics B. Uses Revtex, 13 pages with 11 EPS figure

Innovative Science

Sir, We write as senior scientists about a problem vital to the scientific enterprise and prosperity. Nowadays, funding is a lengthy and complex business. First, universities themselves must approve all proposals for submission. Funding agencies then subject those that survive to peer review, a process by which a few researchers, usually acting anonymously, assess a proposal's chances that it will achieve its goals, is the best value for money, is relevant to a national priority and will impact on a socio-economic problem. Only 25% of proposals received by the funding agencies are funded. These protracted processes force researchers to exploit existing knowledge, severely discourage open-ended studies and are hugely time-consuming. They are also new: before 1970, few researchers wrote proposals. Now they are virtually mandatory

Mapping entanglement in and out of quantum memories

We report entanglement generation in atomic quantum memories via deterministic mapping of photonic entanglement. The atomic entanglement is retrieved back into photon modes after a programmable storage time, with an overall efficiency of 17%

Innovative Science

Sir, We write as senior scientists about a problem vital to the scientific enterprise and prosperity. Nowadays, funding is a lengthy and complex business. First, universities themselves must approve all proposals for submission. Funding agencies then subject those that survive to peer review, a process by which a few researchers, usually acting anonymously, assess a proposal's chances that it will achieve its goals, is the best value for money, is relevant to a national priority and will impact on a socio-economic problem. Only 25% of proposals received by the funding agencies are funded. These protracted processes force researchers to exploit existing knowledge, severely discourage open-ended studies and are hugely time-consuming. They are also new: before 1970, few researchers wrote proposals. Now they are virtually mandatory

An Advanced Apparatus for Integrating Nanophotonics and Cold Atoms

Integrating nanophotonics with cold atoms permits the exploration of novel paradigms in quantum optics and many-body physics. We realize an advanced apparatus which enables the delivery of single-atom tweezer arrays in the vicinity of photonic crystal waveguides

Quantum manipulation and measurement of single atoms in optical cavity QED

Using laser-cooled atoms strongly coupled to a high finesse optical cavity, we have performed real-time continuous measurements of single atomic trajectories in terms of the interaction energy (Eint) with the cavity. Individual transit events reveal a shot-noise limited measurement (fractional) sensitivity of 4×10-4/√Hz to variations in Eint/&planck; within a bandwidth of 1300 kHz. The strong coupling of atom and cavity leads to a maximum interaction energy greater than the kinetic energy of an intracavity laser-cooled atom, even under weak cavity excitation. Evidence of mechanical light forces for intracavity photon number <1 has been observed. The quantum character of the nonlinear optical response of the atom-cavity system is manifested for the trajectory of a single atom

Efficient retrieval of a single excitation stored in an atomic ensemble

We report significant improvements in the retrieval efficiency of a single excitation stored in an atomic ensemble and in the subsequent generation of strongly correlated pairs of photons. A 50% probability of transforming the stored excitation into one photon in a well-defined spatio-temporal mode at the output of the ensemble is demonstrated. These improvements are illustrated by the generation of high-quality heralded single photons with a suppression of the two-photon component below 1% of the value for a coherent state. A broad characterization of our system is performed for different parameters in order to provide input for the future design of realistic quantum networks

Generation and distribution of heralded entanglement between atomic ensembles for scalable quantum networks

Entanglement is generated by path-erasing detection of single photon emitted indistinguishably by two atomic ensembles. We characterize relationship of degree of entanglement to local dephasing. Parallel pairs of entanglement are distributed to polarization entanglement via conditional control