Mathieu beams as versatile light moulds for 3D micro particle assemblies

We present tailoring of three dimensional light fields which act as light moulds for elaborate particle micro structures of variable shapes. Stereo microscopy is used for visualization of the 3D particle assemblies. The powerful method is demonstrated for the class of propagation invariant beams, where we introduce the use of Mathieu beams as light moulds with non-rotationally-symmetric structure. They offer multifarious field distributions and facilitate the creation of versatile particle structures. This general technique may find its application in micro fluidics, chemistry, biology, and medicine, to create highly efficient mixing tools, for hierarchical supramolecular organization or in 3D tissue engineering

Superfluid rotation sensor with helical laser trap

The macroscopic quantum states of the dilute bosonic ensemble in helical laser trap at the temperatures about $10^{-6}\bf {K}$ are considered in the framework of the Gross-Pitaevskii equation. The helical interference pattern is composed of the two counter propagating Laguerre-Gaussian optical vortices with opposite orbital angular momenta $\ell \hbar$ and this pattern is driven in rotation via angular Doppler effect. Macroscopic observables including linear momentum and angular momentum of the atomic cloud are evaluated explicitly. It is shown that rotation of reference frame is transformed into translational motion of the twisted matter wave. The speed of translation equals the group velocity of twisted wavetrain $V_z= \Omega\ell/ k$ and alternates with a sign of the frame angular velocity $\Omega$ and helical pattern handedness $\ell$. We address detection of this effect using currently accessible laboratory equipment with emphasis on the difference between quantum and classical fluids.Comment: 8 pages, 3 figures, accepted to publication Journ.Low Temp.Phy

Holographic optical tweezers induced hierarchical supramolecular organization

Nanocontainers, i.e. particles at the micro and nano scale that can host guest molecules, are of highest interest for various applications especially in nanoscience and biomedicine. Popular examples are the delivery of phar-maceuticals or active agents to specific cell, nerve or tissue domains or the organization of larger scaffolds of artificial matter by arrangements of nancontainers [1]. While in some applications the precise control of the position of individual nanocontainers is negligible, it becomes most important for hierarchical supramolecular organisation. Here, microporous nanocontainers are loaded with guest molecules that are not covalently bound, but occupy cavities of highest geometrical order, and this order is directly transferred to the molecules. The order can be extended from the molecular to the microscopic scale by arranging and organizing the nanocontainers themselves - usually by self-assembly or by chemical means