11 research outputs found
Shaping Laguerre-Gaussian laser modes with binary gratings using a Digital Micromirror Device
Laguerre-Gaussian (LG) beams are used in many research fields, such as
microscopy, laser cavity modes and optical tweezing. We develop a holographic
method of generating pure LG modes (amplitude and phase) with a binary
amplitude-only Digital Micromirror Device (DMD), as an alternative to the
commonly used phase-only Spatial Light Modulator. The advantages of such a DMD
include very high frame rates, low cost and high damage thresholds. We show
that the propagating shaped beams are self-similar and their phase fronts are
of helical shape as demanded. We estimate the purity of the resultant beams to
be above 94%
Rapidly reconfigurable optically induced photonic crystals in hot rubidium vapor
Through periodic index modulation, we create two different types of photonic
structures in a heated rubidium vapor for controlled reflection, transmission
and diffraction of light. The modulation is achieved through the use of the AC
Stark effect resulting from a standing-wave control field. The periodic
intensity structures create translationally invariant index profiles analogous
to photonic crystals in spectral regions of steep dispersion. Experimental
results are consistent with modeling.Comment: 6 pages, 6 figure
Lifetime and Coherence of Two-Level Defects in a Josephson Junction
We measure the lifetime () and coherence () of two-level defect
states (TLSs) in the insulating barrier of a Josephson phase qubit and compare
to the interaction strength between the two systems. We find for the average
decay times a power law dependence on the corresponding interaction strengths,
whereas for the average coherence times we find an optimum at intermediate
coupling strengths. We explain both the lifetime and the coherence results
using the standard TLS model, including dipole radiation by phonons and
anti-correlated dependence of the energy parameters on environmental
fluctuations.Comment: 4 pages, 4 figures and supplementary material (3 pages, 2 figures, 1
table
Direct Wigner tomography of a superconducting anharmonic oscillator
The analysis of wave-packet dynamics may be greatly simplified when viewed in
phase-space. While harmonic oscillators are often used as a convenient platform
to study wave-packets, arbitrary state preparation in these systems is more
challenging. Here, we demonstrate a direct measurement of the Wigner
distribution of complex photon states in an anharmonic oscillator - a
superconducting phase circuit, biased in the small anharmonicity regime. We
test our method on both non-classical states composed of two energy eigenstates
and on the dynamics of a phase-locked wavepacket. This method requires a simple
calibration, and is easily applicable in our system out to the fifth level.Comment: 5 figures, 1 table and supplementary materia
Rapidly Reconfigurable Optically Induced Photonic Crystals in Hot Rubidium Vapor
Through periodic index modulation, we create two different types of photonic structures in a heated rubidium vapor for controlled reflection, transmission, and diffraction of light. The modulation is achieved through the use of the ac Stark effect resulting from a standing-wave control field. The periodic intensity structures create translationally invariant index profiles analogous to photonic crystals in spectral regions of steep dispersion. Experimental results are consistent with modeling