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J Eschner

Publications and source records attributed to J Eschner.

13 recordsLinked to original sources
PubMed2002

Coupling a single atomic quantum bit to a high finesse optical cavity.

The quadrupole S(1/2)-D(5/2) optical transition of a single trapped Ca+ ion, well suited for encoding a quantum bit of information, is coherently coupled to the standing wave field of a high finesse cavity. The coupling is verified by observing the ion's response to both spatial and temporal variations of the intracavity field. We also achieve deterministic coupling of the cavity mode to the ion's vibrational state by selectively exciting vibrational state-changing transitions and by controlling the position of the ion in the standing wave field with nanometer precision.

Journal Article↗
PubMed2001

Light interference from single atoms and their mirror images.

A single atom emitting single photons is a fundamental source of light. But the characteristics of this light depend strongly on the environment of the atom. For example, if an atom is placed between two mirrors, both the total rate and the spectral composition of the spontaneous emission can be modified. Such effects have been observed using various systems: molecules deposited on mirrors, dye molecules in an optical cavity, an atom beam traversing a two-mirror optical resonator, single atoms traversing a microwave cavity and a single trapped electron. A related and equally fundamental phenomenon is the optical interaction between two atoms of the same kind when their separation is comparable to their emission wavelength. In this situation, light emitted by one atom may be reabsorbed by the other, leading to cooperative processes in the emission. Here we observe these phenomena with high visibility by using one or two single atom(s), a collimating lens and a mirror, and by recording the individual photons scattered by the atom(s). Our experiments highlight the intimate connection between one-atom and two-atom effects, and allow their continuous observation using the same apparatus.

Journal Article↗
PubMed2000

Experimental demonstration of ground state laser cooling with electromagnetically induced transparency.

Ground state laser cooling of a single trapped Ca(+)on is achieved with a technique which tailors the absorption profile for the cooling laser by exploiting electromagnetically induced transparency. Using the Zeeman structure of the S(1/2) to P(1/2) dipole transition we achieve up to 90% ground state probability. The new method is robust, easy to implement, and proves particularly useful for cooling several motional degrees of freedom simultaneously, which is of great practical importance for the implementation of quantum logic schemes with trapped ions.

Journal Article↗
PubMed2000

Ground state laser cooling using electromagnetically induced transparency

A laser cooling method for trapped atoms is described which achieves ground state cooling by exploiting quantum interference in a driven Lambda-shaped arrangement of atomic levels. The scheme is technically simpler than existing methods of sideband cooling, yet it can be significantly more efficient, in particular when several motional modes are involved, and it does not impose restrictions on the transition linewidth. We study the full quantum mechanical model of the cooling process for one motional degree of freedom and show that a rate equation provides a good approximation.

Journal Article↗
PubMed1976

[Effect of canrenoate potassium on intraoperative disturbances of electrolyte equilibrium].

In 61 patients the influence of canrenoate potassium on the shift of electrolytes during the intraoperative phase is studied. Without medication of canrenoate potassium depletion of potassium, magnesium and zinc occurs, a sign of transitory intraoperative hyperaldosteronism. On the other hand, preoperative and intraoperative infusion of 1000 mg canrenoate potassium prevents an increased excretion of electrolytes. Causes and consequences of the electrolyte depletion as well as the effect of canrenoate-potassium medication are discussed.

Calcium↗