95 research outputs found
High Brightness Electron Source for Coherent Radiation Production
Adalberto Sciubba, Bruno Crosignani, Giuseppe Schettin
Simultaneous electronic and the magnetic excitation of a ferromagnet by intense THz pulses
The speed of magnetization reversal is a key feature in magnetic data
storage. Magnetic fields from intense THz pulses have been recently shown to
induce small magnetization dynamics in Cobalt thin film on the sub-picosecond
time scale. Here, we show that at higher field intensities, the THz electric
field starts playing a role, strongly changing the dielectric properties of the
cobalt thin film. Both the electronic and magnetic responses are found to occur
simultaneously, with the electric field response persistent on a time scale
orders of magnitude longer than the THz stimulu
Laser and rf synchronization measurements at SPARC
The SPARC project consists in a 150 MeV S-band, high-brilliance linac followed by 6 undulators for FEL radiation production at 530 nm. The linac assembly has been recently completed. During year 2006 a first experimental phase aimed at characterizing the beam emittance in the first 2 m drift downstream the RF gun has been carried out. The low level RF control electronics to monitor and synchronize the RF phase in the gun and the laser shot on the photocathode has been commissioned and extensively tested during the emittance measurement campaign. The laser synchronization has been monitored by measuring the phase of the free oscillation of an RF cavity impulsively excited by the signal of a fast photodiode illuminated by the laser shot. Phase stability measurements are reported, both with and without feedback correction of the slow drifts. A fast intra-pulse phase feedback system to reduce the phase noise produced by the RF power station has been also positively tested
Nonlinear quantum magnetophononics in SrCu(BO)
Harnessing the most advanced capabilities of quantum technologies will
require the ability to control macroscopic quantum states of matter. Quantum
magnetic materials provide a valuable platform for realizing highly entangled
many-body quantum systems, and have been used to investigate phenomena ranging
from quantum phase transitions (QPTs) to fractionalization, topological order
and the entanglement structure of the quantum wavefunction. Although multiple
studies have controlled their properties by static applied pressures or
magnetic fields, dynamical control at the fundamental timescales of their
magnetic interactions remains completely unexplored. However, major progress in
the technology of ultrafast laser pulses has enabled the dynamical modification
of electronic properties, and now we demonstrate the ultrafast control of
quantum magnetism. This we achieve by a magnetophononic mechanism, the driving
of coherent lattice displacements to produce a resonant excitation of the
quantum spin dynamics. Specifically, we apply intense terahertz laser pulses to
excite a collective spin state of the quantum antiferromagnet
SrCu(BO) by resonance with the nonlinear mixing frequency of the
driven phonons that modulate the magnetic interactions. Our observations
indicate a universal mechanism for controlling nonequilibrium quantum many-body
physics on timescales many orders of magnitude faster than those achieved to
date.Comment: 24 pages, 9 figure
- …