40 research outputs found
Amplifying ultraweak transitions in collective systems via quantum interference
We investigate laser-induced quantum interference phenomena in superradiance
processes and in an ensemble of initially excited type closely packed
three-level emitters. The lower doublet levels are pumped with a coherent laser
field. Due to constructive quantum interference effects, the superradiance
occurs on a much weaker atomic transition which is not the case in the absence
of the coherent driving. This result may be of visible relevance for enhancing
ultraweak transitions in atomic or atomic-like systems, respectively, or for
high-frequency lasing effects.Comment: 12 pages, 3 figure
Cooling a quantum circuit via coupling to a multiqubit system
The cooling effects of a quantum LC circuit coupled inductively with an
ensemble of artificial qubits are investigated. The particles may decay
independently or collectively through their interaction with the environmental
vacuum electromagnetic field reservoir. For appropriate bath temperatures and
the resonator's quality factors, we demonstrate an effective cooling well below
the thermal background. In particular, we found that for larger samples the
cooling efficiency is better for independent qubits. However, the cooling
process can be faster for collectively interacting particles.Comment: 5 pages, 3 figure
Fast phonon dynamics of a nanomechanical oscillator due to cooperative effects
We investigate the coupled-system dynamics of two-level quantum dots placed
on a vibrating nanomechanical resonator. The ensemble of quantum dots exhibits
superradiance features which are transferred to the mechanical degrees of
freedom representing fast quantum dynamics and enhanced phonon emission in a
nanomechanical setup, resembling of the superradiance effect.Comment: 6 pages, 4 figure