19 research outputs found
Polarization-preserving confocal microscope for optical experiments in a dilution refrigerator with high magnetic field
We present the design and operation of a fiber-based cryogenic confocal
microscope. It is designed as a compact cold-finger that fits inside the bore
of a superconducting magnet, and which is a modular unit that can be easily
swapped between use in a dilution refrigerator and other cryostats. We aimed at
application in quantum optical experiments with electron spins in
semiconductors and the design has been optimized for driving with, and
detection of optical fields with well-defined polarizations. This was
implemented with optical access via a polarization maintaining fiber together
with Voigt geometry at the cold finger, which circumvents Faraday rotations in
the optical components in high magnetic fields. Our unit is versatile for use
in experiments that measure photoluminescence, reflection, or transmission, as
we demonstrate with a quantum optical experiment with an ensemble of
donor-bound electrons in a thin GaAs film.Comment: 9 pages, 7 figure
Electromagnetically Induced Transparency with an Ensemble of Donor-Bound Electron Spins in a Semiconductor
We present measurements of electromagnetically induced transparency with an
ensemble of donor- bound electrons in low-doped n-GaAs. We used optical
transitions from the Zeeman-split electron spin states to a bound trion state
in samples with optical densities of 0.3 and 1.0. The electron spin dephasing
time T* \approx 2 ns was limited by hyperfine coupling to fluctuating nuclear
spins. We also observe signatures of dynamical nuclear polarization, but find
these effects to be much weaker than in experiments that use electron spin
resonance and related experiments with quantum dots.Comment: 4 pages, 4 figures; Improved analysis of data in Fig. 3, corrected
factors of 2 and p
Electromagnetically induced transparency in low-doped n-GaAs
We report the observation of electromagnetically induced transparency (EIT) with an ensemble of donor-bound electrons in low-doped n-GaAs. We used pure GaAs layers with Si doping at very low concentration in a strong magnetic field. EIT was implemented with the two optical transitions that exist for the three-level system that is formed by the two electron spin states and a donor-bound trion state. Our results show that EIT with n-GaAs can serve as a platform for studies of nonlocal quantum entanglement with spins in semiconductors, as well as for controlling and probing dynamical nuclear polarization with coherent electron spins