Summary form only given.Atom interferometers have opened up new areas of fundamental and applied research. As well known from photon optics, multiple-beam interferometers offer an increased sensitivity on the relative phases between interfering waves. Very recently, first atomic multiple-beam interferometers were realized. These concepts are based on an atomic beam that is spatially split into coherent partial de Broglie waves, where the number of interfering waves is determined by the internal atomic multi-level scheme. We report on time-domain atomic interferometry within a two-level system.
Summary form only given.Atom interferometers have opened up new areas of fundamental and applied research. As well known from photon optics, multiple-beam interferometers offer an increased sensitivity on the relative phases between interfering waves. Very recently, first atomic multiple-beam interferometers were realized. These concepts are based on an atomic beam that is spatially split into coherent partial de Broglie waves, where the number of interfering waves is determined by the internal atomic multi-level scheme. We report on time-domain atomic interferometry within a two-level system.
We report on experiments of multiple-beam atom interferometry in the time domain. Laser-cooled and trapped atoms interact with atomic ``multiple beam splitters'' realized by time sequences of resonant laser pulses. The output signals of the interferometers show Fabry-Perot-like high-finesse interference structures. The number of interfering de Broglie waves is adjustable and in principle not limited in this scheme. We present the experimental realization of up to 160 interfering partial waves.
In recent years interferometry with atoms has opened up many applications within the fields of precision measurements of atomic properties and fundamental constants, the investigation of quantum mechanical effects and the realization of atomic frequency standards.In this work novel concepts and physical prospects of atom interferometry -based on light for the atomic beamsplitting process -are discussed and analyzed.As analogous to light optics the sensitivity of an atom interferometer can be improved by increasing the number of partial waves taking part in the interference process.In this work two basically different schemes for the realization of atomic multiple-beam interferences have been developed and investigated.The increased sensitivity for measurements of external potentials has been demonstrated with a new atomic three-beam interferometer.A time-domain multiple-beam interferometer for the first time yields Fabry-Perot like interference signals with high finesse.In the presented experiments these signals correspond to interference of 160 partial atomic waves.By this means the principle of multiple-beam interferometry, which is an important standard tool in light optics, has been successfully transferred to atom optics.Furthermore different schemes have been developed which base on an extension of the interferometric beamsplitting mechanism from the excitation of two to four internal atomic levels.These schemes represent an inclusion of the atomic polarization as an additional degree of freedom.This opens the possibility for more efficient interferometer geometries.These novel interferometers show a contrast which is increased by about 65% and improved accuracy in the determination of the exact line center.In addition polarized atoms in an interferometer offer very interesting prospects concerning the investigation of fundamental quantum mechanical aspects.In this work a detailed proposal for the systematic observation of a wavefunction collapse within a longitudinal atom interferometer is discussed.It turns out that for certain parameters this observation represents a so-called interaction-free quantum measurement.Besides the experimental realization each interferometer scheme described in this work has also been subjected to theoretical investigations.The corresponding calculations are based on a matrix-algorithm by Bordé yielding analytical expressions for the interference signals.With respect to the application of atom interferometers as optical frequency standards the results of this work open various prospects for strongly improved future precision measurements.Atominterferometrie, Laserkühlung, Spektroskopie Zusammenfassung Die Interferometrie mit Atomen hat in den letzten Jahren ein weitreichendes Anwendungsfeld im Bereich der Präzisionsmessung von atomaren Eigenschaften und Naturkonstanten, des Studiums quantenmechanischer Effekte und der Realisierung atomarer Frequenzstandards erschlossen.Die vorliegende Arbeit diskutiert und analysiert neuartige Konzepte und physikalische Perspektiven der Atominterferometrie, die Licht als Strahlteiler für die Materiewellen einsetzen.Analog zur Lichtoptik kann die Empfindlichkeit eines Atominterferometers durch Erhöhung der Anzahl interferierender Teilwellen enorm gesteigert werden.In dieser Arbeit wurden zwei grundsätzlich verschiedene Konzepte zur Realisierung atomarer Vielstrahl-Interferenzen entwickelt und untersucht.Anhand eines stationären atomaren Dreistrahl-Interferometers wurde dabei die gesteigerte Empfindlichkeit für die Messung externer Potentiale demonstriert.Ein gepulstes Vielstrahl-Interferometer im Zeitraum liefert Fabry-Perotähnliche Signale hoher Finesse, die in den vorgestellten Experimenten durch Interferenz von bis zu 160 atomaren Teilwellen entstehen.Als wesentliches Ergebnis dieser Arbeit ist es damit gelungen, das Prinzip der Vielstrahl-Interferenz, die in der Lichtoptik schon lange unentbehrliches Werkzeug ist, auf die Atomoptik zu übertragen.Es wurden darüberhinaus neuartige Schemata konzipiert und verwirklicht, die den interferometrischen Strahlteilungsmechanismus durch kohärente Anregung von vier statt lediglich zwei internen atomaren Zuständen in Flexibilität und Effizienz deutlich erweitern.Die Polarisation der Atome im Interferometer wird dadurch als zusätzlicher Freiheitsgrad miteinbezogen.Es werden so neue Interferometergeometrien möglich, die sich durch einen um bis zu 65% verbesserten Signalkontrast sowie eine erhöhte Genauigkeit in der Bestimmung der absoluten Linienmitte auszeichnen.Polarisierte Atome im Interferometer bieten aber auch interessante Perspektiven für die Untersuchung grundlegender quantenmechanischer Fragestellungen.In diesem Zusammenhang wird ein konkreter Vorschlag für ein Experiment mit Modellcharakter entwickelt, das die systematische Beobachtung des "Kollaps" einer Wellenfunktion innerhalb eines rein longitudinalen Atominterferometers ermöglicht und für bestimmte Parameter eine sogenannte "Wechselwirkungsfreie Quantenmessung" darstellt.Alle untersuchten interferometrischen Anordnungen wurden auf der Basis eines Matrixformalismus nach Bordé theoretisch beschrieben und sind damit auch analytisch vergleichbar.Die im Rahmen dieser Arbeit gewonnenen Erkenntnisse zur Interferometrie eröffnen -vor allem im Hinblick auf die Realisierung eines Frequenzstandards an lasergekühlten Atomen -ein breites Spektrum für weitergehende, verbesserte Präzisionsmessungen.
Atomic interferometry was born recently, towards the end of the 1980s. Its development has been extremely fast, new techniques being pioneered independently and almost simultaneously in different laboratories all over the world. Nowadays, these techniques have reached a high level of sophistication, opening a wide area of fundamental and practical applications. In this paper the general architecture of interferometers in which matter waves are coherently manipulated is described. Various realizations of atom and molecule interferometers are reported, together with the major results obtained with each type of interferometer. Finally, new trends and perspectives are given. Whilst the techniques seem to be almost completely achieved, new developments are coming up, such as the use of new and non-ordinary sources. Forthcoming applications are numerous. They deal with the most fundamental aspects of quantum mechanics, with the metrology of fundamental constants, with the use of interferometers as very sensitive probes of external interactions and inertial effects, with atomic nanolithography, etc.
Matter - wave interferometry began with the development of electron interferometers and neutron interferometers in the 1950s and 1960s, but it wasn't until 1991 that the first atom matter - wave interferometer was realized. This was followed by a surge of activity sparked by the advent of sources of ultracold laser-cooled atoms. Some of the potential advantages of atom interferometry over neutron interferometry include: much higher particle fluxes, lower particle velocities, larger particle masses, particles with internal states, and laboratory-based sources. This volume is the first text on atom interferometry. It consists of ten comprehensive review articles by leading researchers in the field, many of whom pioneered the first atom interferometers in 1991. The articles describe the different types of atom interferometers developed to date, ranging from the three-grating Mach - Zehnder interferometer based on nanofabricated grating structures (MIT) or standing-wave light-field gratings (Innsbruck), to the Talbot - Lau atom interferometer (Berkeley and Michigan), to atom interferometers based on internal-state labelling such as separated light-field interferometers (PTB, Hannover and Paris-Nord) and light-pulse interferometers (Stanford). Some of the recent applications of atom interferometry described in the articles include high precision measurements of rotations, the gravitational acceleration, and the fine structure constant (Stanford); measurements of topological phases (PTB and Hannover); correlation experiments with atoms and photons (Konstanz) and with pairs of atoms (Tokyo); holographic manipulation of atoms (Tokyo); and experiments on the quantum theory of measurement (Garching, Harvard and Texas A&M). In summary, this volume provides an excellent up-to-date account of atom interferometry and is recommended as essential reading for all researchers and would-be researchers in the field. At the same time it contains sufficient background material and theory to serve as an excellent introduction for the non-specialist. The field is presently moving at such a rapid pace, however, that many of the latest results reported in this volume will already have been superseded by the time it reaches the library shelves.
Thanks to the wave nature of matter, it's possible to build the atomic analog of an optical interferometer, although it's extremely difficult, because the de Broglie wavelengths of atoms are typically 10 000 times shorter than those of light. The feat was accomplished four years ago by a number of groups, each with a different scheme for splitting and recombining the matter waves. (See PHYSICS TODAY, July 1991, page 17.) We are now starting to see the fulfillment of the hopes raised by those first atom interferometers as researchers hone their interferometers to yield ever more precise values of fundamental constants or explore fundamental aspects of quantum mechanics such as Berry's phase. For example, Steven Chu and his colleagues at Stanford University have measured the ratio h/m of Planck's constant to the mass of a cesium atom with a precision of one part in 107, although the systematic errors are at the level of 1 part in 106. An experiment to improve the absolute accuracy of the h/m measurement to a few parts in 109 is underway. This ratio is one factor in the determination of the finestructure constant.