  Amplified ultrashort laser pulses are useful in many fields of science and
engineering. Pushing the frontiers of ultrashort pulse generation will lead to
new applications in biomedical imaging, communications and sensing. We propose
a new, quantum approach to ultrashort pulse generation using transient quantum
coherence which predicts order of magnitude stronger pulses generated with
lower input energy than in the steady-state regime, reducing the practical
heating limitations. This femtosecond quantum-coherent analog of nanosecond
Q-switching is not limited by the pulse duration constraints of the latter,
and, in principle, may be used for a variety of lasers including x-ray and
plasmon nanolasers. We apply this approach to generation of giant plasmon
pulses and achieve quantum control of plasmon relaxation dynamics by varying
the drive pulse delay, amplitude and duration. We provide insights into the
control mechanisms, and discuss future implementations and applications of this
new source of ultrashort nanooptical fields.
