On the Phenomenology of Tachyon Radiation

We present a brief overview of the different kinds of electromagnetic radiations expected to come from (or to be induced by) space-like sources (tachyons). New domains of radiation are here considered; and the possibility of experimental observation of tachyons via electromagnetic radiation is discussed

Internal decoherence in nano-object interferometry due to phonons

We discuss the coherent splitting and recombining of a nanoparticle in a mesoscopic "closed-loop" Stern-Gerlach interferometer in which the observable is the spin of a single impurity embedded in the particle. This spin, when interacting with a pulsed magnetic gradient, generates the force on the particle. We calculate the internal decoherence which arises as the displaced impurity excites internal degrees of freedom (phonons) that may provide Welcher Weg information and preclude interference. We estimate the constraints this decoherence channel puts on future interference experiments with massive objects. We find that for a wide range of masses, forces and temperatures, phonons do not inhibit Stern-Gerlach interferometry with micro-scale objects. However, phonons do constitute a fundamental limit on the splitting of larger macroscopic objects if the applied force induces phonons.Comment: 10 pages, 6 figures, submitted to Festschrift in honor of Nobel prize awarded to R. Penros

Fundamental Limits for Coherent Manipulation on Atom Chips

The limitations for the coherent manipulation of neutral atoms with fabricated solid state devices, so-called `atom chips', are addressed. Specifically, we examine the dominant decoherence mechanism, which is due to the magnetic noise originating from the surface of the atom chip. It is shown that the contribution of fluctuations in the chip wires at the shot noise level is not negligible. We estimate the coherence times and discuss ways to increase them. Our main conclusion is that future advances should allow for coherence times as long as one second, a few micrometers away from the surface.Comment: selected papers of the DPG spring meeting `Quantum Optics' (Osnabrueck, Germany, 4-8 march 2002), submitted to Applied Physics

Robust spatial coherence 5 μ\,\mum from a room-temperature atom chip

We study spatial coherence near a classical environment by loading a Bose-Einstein condensate into a magnetic lattice potential and observing diffraction. Even very close to a surface (5$\,\mu$m), and even when the surface is at room temperature, spatial coherence persists for a relatively long time ($\ge$500$\,$ms). In addition, the observed spatial coherence extends over several lattice sites, a significantly greater distance than the atom-surface separation. This opens the door for atomic circuits, and may help elucidate the interplay between spatial dephasing, inter-atomic interactions, and external noise.Comment: 15 pages, 14 figures, revised for final publication. This manuscript includes in-depth analysis of the data presented in arXiv:1502.0160

One-mirror Fabry-Perot and one-slit Young interferometry

We describe a new and distinctive interferometry in which a probe particle scatters off a superposition of locations of a single free target particle. In one dimension, probe particles incident on superposed locations of a single "mirror" can interfere as if in a Fabry-Perot interferometer; in two dimensions, probe particles scattering off superposed locations of a single "slit" can interfere as if in a two-slit Young interferometer. The condition for interference is loss of orthogonality of the target states and reduces, in simple examples, to transfer of orthogonality from target to probe states. We analyze experimental parameters and conditions necessary for interference to be observed.Comment: 5 pages, 2 figures, RevTeX, submitted to PR