We have scattered single photons from interfering de Broglie waves in an atom interferometer and observed contrast loss and revivals as the separation of the interfering paths at the point of scattering is increased. Additionally, we have demonstrated that the lost coherence can be recovered by observing only atoms that are correlated with photons emitted into a limited angular range.

We have measured the phase shift induced by rotation of an atom interferometer at rates of 22 to 12 earth rates and obtained 1% agreement with the predicted Sagnac phase shift for atomic matter waves. The rotational rms noise of our interferometer was 42 milliearth rates for 1 sec of integration time, within 9% of shot noise. The high sensitivity and agreement of predicted and measured behavior suggest useful future scientific applications of atom interferometers as inertial sensors. [S0031-9007(96)02186-2]

We have produced an intense, pure beam of sodium molecules (Naz) by using light forces to separate the atomic and molecular species in a seeded supersonic beam. We used diffraction from a microfabricated grating to study the atomic and molecular sodium in the beam. Using three of these gratings, we constructed a molecule interferometer with fully separated beams and high contrast fringes.We measured both the real and imaginary parts of the index of refraction of neon gas for Na& molecule de Broglie waves by inserting a gas cell in one arm of the interferometer.PACS numbers: 03.75.b, 07.77.Gx, 34.20.Gj Quantum mechanical treatment of the center-of-mass motion of increasingly complex systems is an important theme in modern physics. This issue is manifest theoretically in studies of the transition from quantum through mesoscopic to classical regimes and experimentally in efforts to coherently control and manipulate the external spatial coordinates of complex systems (e.g., matter wave optics and interferometry).Recently, matter wave optics and interferometry have been extended to atoms with the many techniques for the coherent manipulation of the external degrees of freedom of atoms constituting a new field called atom optics [1]. The present work extends and develops techniques of atom optics into the domain of moleculessystems characterized by many degenerate and nondegenerate internal quantum states. Whereas internal state coherences in complex molecules have long been cleverly manipulated in spectroscopy in both the radio [2] and optical frequency domains [3,4], here we coherently manipulate exclusively the center-of-mass motion [5]. This work, which culminates in the use of a molecule interferometer with spatially separated beams to determine hitherto unmeasurable molecular properties, demonstrates the applicability of molecular interferometers to precision measurements in molecular physics, some of which may have applications to fundamental physics experiments using specific molecules [6].Our experiment combines several techniques from atom optics to make and use a molecule interferometer whose paths are well separated in position and momentum. Using an incident supersonic beam containing both Na atoms and dimers (Naq), we apply resonant light forces to selectively remove the Na atoms, leaving a pure Na& beam. We then use nanofabricated diffraction gratings, first to study the characteristics of the molecular beam and subsequently as coherent beam splitters to make a molecule interferometer with high contrast fringes.Finally, we insert a gas cell in one path of the separated beam interferometer and measure the complex index of refraction for Na~de Broglie waves in Ne gas. This provides new information on the long-range part of the Na~-Ne potential.The beam of sodium atoms and dimers was produced in a seeded supersonic expansion using either argon or krypton as the carrier gas. By heating the Na reservoir to 800'C (Na vapor pressure -300 torr), we were able to enhance the population of sodium dimers in the b...

Interference with atomic and molecular matter waves is a rich branch of atomic physics and quantum optics. It started with atom diffraction from crystal surfaces and the separated oscillatory fields technique used in atomic clocks. Atom interferometry is now reaching maturity as a powerful art with many applications in modern science. In this review the basic tools for coherent atom optics are described including diffraction by nanostructures and laser light, three-grating interferometers, and double wells on atom chips. Scientific advances in a broad range of fields that have resulted from the application of atom interferometers are reviewed. These are grouped in three categories: ͑i͒ fundamental quantum science, ͑ii͒ precision metrology, and ͑iii͒ atomic and molecular physics. Although some experiments with Bose-Einstein condensates are included, the focus of the review is on linear matter wave optics, i.e., phenomena where each single atom interferes with itself.