22 research outputs found
High-impedance surface acoustic wave resonators
Because of their small size, low loss, and compatibility with magnetic fields
and elevated temperatures, surface acoustic wave resonators hold significant
potential as future quantum interconnects. Here, we design, fabricate, and
characterize GHz-frequency surface acoustic wave resonators with the potential
for strong capacitive coupling to nanoscale solid-state quantum systems,
including semiconductor quantum dots. Strong capacitive coupling to such
systems requires a large characteristic impedance, and the resonators we
fabricate have impedance values above 100 . We achieve such high
impedance values by tightly confining a Gaussian acoustic mode. At the same
time, the resonators also have low loss, with quality factors of several
thousand at millikelvin temperatures. These high-impedance resonators are
expected to exhibit large vacuum electric-field fluctuations and have the
potential for strong coupling to a variety of solid-state quantum systems
High-Energy Passive Mode-Locking of Fiber Lasers
Mode-locking refers to the generation of ultrashort optical pulses in laser systems. A comprehensive study of achieving high-energy pulses in a ring cavity fiber laser that is passively mode-locked by a series of waveplates and a polarizer is presented in this paper. Specifically, it is shown that the multipulsing instability can be circumvented in favor of bifurcating to higher-energy single pulses by appropriately adjusting the group velocity dispersion in the fiber and the waveplate/polarizer settings in the saturable absorber. The findings may be used as practical guidelines for designing high-power lasers since the theoretical model relates directly to the experimental settings
Quantum coherence and interaction-free measurements
We investigate the extent to which ``interaction-free'' measurements perturb
the state of quantum systems. We show that the absence of energy exchange
during the measurement is not a sufficient criterion to preserve that state, as
the quantum system is subject to measurement dependent decoherence. While it is
possible in general to design interaction-free measurement schemes that do
preserve that state, the requirement of quantum coherence preservation rapidly
leads to a very low efficiency. Our results, which have a simple interpretation
in terms of ``which-way'' arguments, open up the way to novel quantum
non-demolition techniques.Comment: 4 pages incl. 2 PostScript figures (.eps), LaTeX using RevTeX,
submitted to Phys. Rev. A (Rapid Comm.
Media 1: Spatiotemporal soliton laser
Originally published in Optica on 20 August 2014 (optica-1-2-101