18,236 research outputs found
Terawatt-scale sub-10-fs laser technology - key to generation of GW-level attosecond pulses in X-ray free electron laser
We propose a technique for the production of attosecond X-ray pulses which is
based on the use of X-ray SASE FEL combined with a femtosecond laser system. A
few-cycle optical pulse from a Ti:sapphire laser interacts with the electron
beam in a two-period undulator resonant to 800 nm wavelength and produces
energy modulation within a slice of the electron bunch. Following the energy
modulator the electron beam enters the X-ray undulator and produces SASE
radiation. Due to energy modulation the frequency is correlated to the
longitudinal position within the few-cycle-driven slice of SASE radiation
pulse. The largest frequency offset corresponds to a single-spike pulse in the
time domain which is confined to one half-oscillation period near the central
peak electron energy. The selection of single-spike pulses is achieved by using
a crystal monochromator after the X-ray undulator. Our studies show that the
proposed technique is capable to produce 300 attoseconds long single pulses
with GW-level output power in the 0.1 nm wavelength range, and is applicable to
the European X-Ray Laser Project XFEL and the Linac Coherent Light Source at
SLAC.Comment: 19 pages, 13 figure
VUV/EUV ionising radiation and atoms and ions: dual laser plasma investigations
The interaction of ionising radiation with atoms and ions is a key fundamental process. This report concentrates on studies of photoexcitation/photoionisation using laser-produced plasmas as continuum sources and synchronised laser plasma plumes to provide the absorbing atom or ion species. Examples from studies of the interaction of ionising radiation with atoms and ions ranging from few-electron atomic and ionic systems to the many-electron high atomic number actinides are reviewed and illustrate the advantages and limitations of the Dual Laser Plasma technique
Coherent spin control at the quantum level in an ensemble-based optical memory
Long-lived quantum memories are essential components of a long-standing goal
of remote distribution of entanglement in quantum networks. These can be
realized by storing the quantum states of light as single-spin excitations in
atomic ensembles. However, spin states are often subjected to different
dephasing processes that limit the storage time, which in principle could be
overcome using spin-echo techniques. Theoretical studies have suggested this to
be challenging due to unavoidable spontaneous emission noise in ensemble-based
quantum memories. Here we demonstrate spin-echo manipulation of a mean spin
excitation of 1 in a large solid-state ensemble, generated through storage of a
weak optical pulse. After a storage time of about 1 ms we optically read out
the spin excitation with a high signal-to-noise ratio. Our results pave the way
for long-duration optical quantum storage using spin-echo techniques for any
ensemble-based memory.Comment: 5 pages, 2 figures, 1 tabl
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