Preparation of an Exponentially Rising Optical Pulse for Efficient Excitation of Single Atoms in Free Space

We report on a simple method to prepare optical pulses with exponentially rising envelope on the time scale of a few ns. The scheme is based on the exponential transfer function of a fast transistor, which generates an exponentially rising envelope that is transferred first on a radio frequency carrier, and then on a coherent cw laser beam with an electro-optical phase modulator (EOM). The temporally shaped sideband is then extracted with an optical resonator and can be used to efficiently excite a single Rb-87 atom.Comment: 3 pages, 4 figures, small technical not

Excitation of a single atom with exponentially rising light pulses

We investigate the interaction between a single atom and optical pulses in a coherent state with a controlled temporal envelope. In a comparison between a rising exponential and a square envelope, we show that the rising exponential envelope leads to a higher excitation probability for fixed low average photon numbers, in accordance to a time-reversed Weisskopf-Wigner model. We characterize the atomic transition dynamics for a wide range of the average photon numbers, and are able to saturate the optical transition of a single atom with ~50 photons in a pulse by a strong focusing technique. For photon numbers of ~1000 in a 15ns long pulse, we clearly observe Rabi oscillations.Comment: 5 pages, 6 figure

Interaction of light with a single atom in the strong focusing regime

We consider the near-resonant interaction between a single atom and a focused light mode, where a single atom localized at the focus of a lens can scatter a significant fraction of light. Complementary to previous experiments on extinction and phase shift effects of a single atom, we report here on the measurement of coherently backscattered light. The strength of the observed effect suggests combining strong focusing with the well-established methods of cavity QED. We consider theoretically a nearly concentric cavity, which should allow for a strongly focused optical mode. Simple estimates show that in a such case one can expect a significant single photon Rabi frequency. This opens new perspectives and a possibility to scale up the system consisting of many atom+cavity nodes for quantum networking due to a significant technical simplification of the atom--light interfaces.Comment: 7 pages, 6 figures, followup of workshop "Single photon technologies" in Boulder, CO, 200

Quantum absorption refrigerator with trapped ions

Thermodynamics is one of the oldest and well-established branches of physics that sets boundaries to what can possibly be achieved in macroscopic systems. While it started as a purely classical theory, it was realized in the early days of quantum mechanics that large quantum devices, such as masers or lasers, can be treated with the thermodynamic formalism. Remarkable progress has been made recently in the miniaturization of heat engines all the way to the single Brownian particle as well as to a single atom. However, despite several theoretical proposals, the implementation of heat machines in the fully quantum regime remains a challenge. Here, we report an experimental realization of a quantum absorption refrigerator in a system of three trapped ions, with three of its normal modes of motion coupled by a trilinear Hamiltonian such that heat transfer between two modes refrigerates the third. We investigate the dynamics and steady-state properties of the refrigerator and compare its cooling capability when only thermal states are involved to the case when squeezing is employed as a quantum resource. We also study the performance of such a refrigerator in the single shot regime, and demonstrate cooling below both the steady-state energy and the benchmark predicted by the classical thermodynamics treatment.Comment: 11 pages, 7 figures, 2 table