7,133 research outputs found
Multiple Rabi Splittings under Ultra-Strong Vibrational Coupling
From the high vibrational dipolar strength offered by molecular liquids, we
demonstrate that a molecular vibration can be ultra-strongly coupled to
multiple IR cavity modes, with Rabi splittings reaching of the vibration
frequencies. As a proof of the ultra-strong coupling regime, our experimental
data unambiguously reveal the contributions to the polaritonic dynamics coming
from the anti-resonant terms in the interaction energy and from the dipolar
self-energy of the molecular vibrations themselves. In particular, we measure
the opening of a genuine vibrational polaritonic bandgap of ca. meV. We
also demonstrate that the multimode splitting effect defines a whole
vibrational ladder of heavy polaritonic states perfectly resolved. These
findings reveal the broad possibilities in the vibrational ultra-strong
coupling regime which impact both the optical and the molecular properties of
such coupled systems, in particular in the context of mode-selective chemistry.Comment: 10 pages, 9 figure
XUV Frequency Combs via Femtosecond Enhancement Cavities
We review the current state of tabletop extreme ultraviolet (XUV) sources
based on high harmonic generation (HHG) in femtosecond enhancement cavities
(fsEC). Recent developments have enabled generation of high photon flux (1014
photons/sec) in the XUV, at high repetition rates (>50 MHz) and spanning the
spectral region from 40 nm - 120 nm. This level of performance has enabled
precision spectroscopy with XUV frequency combs and promises further
applications in XUV spectroscopic and photoemission studies. We discuss the
theory of operation and experimental details of the fsEC and XUV generation
based on HHG, including current technical challenges to increasing the photon
flux and maximum photon energy produced by this type of system. Current and
future applications for these sources are also discussed.Comment: invited review article, 38 page
High-power multi-megahertz source of waveform-stabilized few-cycle light
Waveform-stabilized laser pulses have revolutionized the exploration of the electronic structure and dynamics of matter by serving as the technological basis for frequency-comb and attosecond spectroscopy. Their primary sources, mode-locked titanium-doped sapphire lasers and erbium/ytterbium-doped fibre lasers, deliver pulses with several nanojoules energy, which is insufficient for many important applications. Here we present the waveform-stabilized light source that is scalable to microjoule energy levels at the full (megahertz) repetition rate of the laser oscillator. A diode-pumped Kerr-lens-mode-locked Yb:YAG thin-disk laser combined with extracavity pulse compression yields waveform-stabilized few-cycle pulses (7.7 fs, 2.2 cycles) with a pulse energy of 0.15 mJ and an average power of 6W. The demonstrated concept is scalable to pulse energies of several microjoules and near-gigawatt peak powers. The generation of attosecond pulses at the full repetition rate of the oscillator comes into reach. The presented system could serve as a primary source for frequency combs in the mid infrared and vacuum UV with unprecedented high power levels
Generating green to red light with semiconductor lasers
Diode lasers enable one to continuously cover the 730 to 1100 nm range as
well as the 370 to 550 nm range by frequency doubling, but a large part of the
electro-magnetic spectrum spanning from green to red remains accessible only
through expensive and unpractical optically pumped dye lasers. Here we devise a
method to multiply the frequency of optical waves by a factor 3/2 with a
conversion that is phase-coherent and highly efficient. Together with harmonic
generation, it will enable one to cover the visible spectrum with semiconductor
lasers, opening new avenues in important fields such as laser spectroscopy and
optical metrology.Comment: to be published on Optics Expres
Interferometers as Probes of Planckian Quantum Geometry
A theory of position of massive bodies is proposed that results in an
observable quantum behavior of geometry at the Planck scale, . Departures
from classical world lines in flat spacetime are described by Planckian
noncommuting operators for position in different directions, as defined by
interactions with null waves. The resulting evolution of position wavefunctions
in two dimensions displays a new kind of directionally-coherent quantum noise
of transverse position. The amplitude of the effect in physical units is
predicted with no parameters, by equating the number of degrees of freedom of
position wavefunctions on a 2D spacelike surface with the entropy density of a
black hole event horizon of the same area. In a region of size , the effect
resembles spatially and directionally coherent random transverse shear
deformations on timescale with typical amplitude . This quantum-geometrical "holographic noise" in position is not
describable as fluctuations of a quantized metric, or as any kind of
fluctuation, dispersion or propagation effect in quantum fields. In a Michelson
interferometer the effect appears as noise that resembles a random Planckian
walk of the beamsplitter for durations up to the light crossing time. Signal
spectra and correlation functions in interferometers are derived, and predicted
to be comparable with the sensitivities of current and planned experiments. It
is proposed that nearly co-located Michelson interferometers of laboratory
scale, cross-correlated at high frequency, can test the Planckian noise
prediction with current technology.Comment: 23 pages, 6 figures, Latex. To appear in Physical Review
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