270 research outputs found
Ultrafast preparation and strong-field ionization of an atomic Bell-like state
Molecules are many body systems with a substantial amount of entanglement
between their electrons. Is there a way to break the molecular bond of a
diatomic molecule and obtain two atoms in their ground state which are still
entangled and form a Bell-like state? We present a scheme that allows for the
preparation of such entangled atomic states from single oxygen molecules on
femtosecond time scales. The two neutral oxygen atoms are entangled in the
magnetic quantum number of their valence electrons. In a time-delayed probe
step, we employ non-adiabatic tunnel ionization, which is a magnetic quantum
number-sensitive mechanism. We then investigate correlations by comparing
single and double ionization probabilities of the Bell-like state. The
experimental results agree with the predictions for an entangled state.Comment: 20 pages, 7 figures, 1 tabl
Holographic detection of parity in atomic and molecular orbitals
We introduce a concise methodology to detect the parity of atomic and molecular orbitals based on photoelectron holography, which is more general than the existing schemes. It fully accounts for the Coulomb distortions of electron trajectories, does not require sculpted fields to retrieve phase information and, in principle, is applicable to a broad range of electron momenta. By comparatively measuring the differential photoelectron spectra from strong-field ionization of
N
2
molecules and their companion atoms of Ar, some photoelectron holography patterns are found to be dephased for both targets. This is well reproduced by the full-dimensional time-dependent Schrödinger equation and the Coulomb quantum-orbit strong-field approximation (CQSFA) simulation. Using the CQSFA, we trace back our observations to different parities of the
3
p
orbital of Ar and the highest-occupied molecular orbital of
N
2
via interfering Coulomb-distorted quantum orbits carrying different initial phases. This method could in principle be used to extract bound-state phases from any holographic structure, with a wide range of potential applications in recollision physics and spectroscopy
Angular dependence of the Wigner time delay upon strong field ionization from an aligned p-orbital
We present experimental data on the strong-field ionization of the argon
dimer in a co-rotating two-color (CoRTC) laser field. We observe a sub-cycle
interference pattern in the photoelectron momentum distribution and infer the
Wigner time delay using holographic angular streaking of electrons (HASE). We
find that the Wigner time delay varies by more than 400 attoseconds as a
function of the electron emission direction with respect to the molecular axis.
The measured time delay is found to be independent of the parity of the
dimer-cation and is in good agreement with our theoretical model based on the
ionization of an aligned atomic p-orbital.Comment: 6 pages, 4 figure
Experimental fingerprint of the electron's longitudinal momentum at the tunnel exit in strong field ionization
We present experimental data on the strong field tunnel ionization of argon
in a counter-rotating two-color (CRTC) laser field. We find that the initial
momentum component along the tunneling direction changes sign comparing the
rising and the falling edge of the CRTC field. If the initial momentum at the
tunnel exit points in the direction of the ion at the instant of tunneling,
this manifests as an enhanced Coulomb interaction of the outgoing electron with
its parent ion. Our conclusions are in accordance with predictions based on
strong field approximation.Comment: 6 pages, 4 figure
Developing a Reduced Gravity Testbed for the Nanoparticle Field Extraction Thruster
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77095/1/AIAA-2009-5194-670.pd
Sideband Modulation by Sub-Cycle Interference
We experimentally and theoretically show that the electron energy spectra
strongly depend on the relative helicity in highly intense, circularly
polarized two-color laser fields which is an unexpected finding. The employed
counter-rotating two-color (CRTC) fields and the co-rotating two-color (CoRTC)
fields are both a superposition of circularly polarized laser pulses at a
central wavelength of 390 nm and 780 nm (intensitiy ratio
). For the CRTC field, the measured electron energy
spectrum is dominated by peaks that are spaced by 3.18 eV (corresponds to the
photon energy of light at a wavelength of 390 nm). For the CoRTC field, we
observe additional energy peaks (sidebands). Using our semi-classical,
trajectory-based models, we conclude that the sideband intensity is modulated
by a sub-cycle interference, which sensitively depends on the relative helicity
in circularly polarized two-color fields.Comment: 7 pages, 4 figure
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