25 research outputs found
Laser and microwave spectroscopy of even-parity Rydberg states of neutral ytterbium and Multichannel Quantum Defect Theory analysis
New measurements of high-lying even parity and
levels of neutral Yb are presented in this paper.
Spectroscopy is performed by a two-step laser excitation from the ground state
, and the Rydberg levels are detected by using the
field ionization method. Additional two-photon microwave spectroscopy is used
to improve the relative energy accuracy where possible. The spectroscopic
measurements are complemented by a multichannel quantum defect theory (MQDT)
analysis for the J=0 and the two-coupled J=2 even parity series. We compare our
results with the previous analysis of Aymar {\it{et al}} \cite{Aymar_1980} and
analyze the observed differences. From the new MQDT models, a revised value for
the first ionization limit cm is proposed.Comment: 15 pages, 3 figure
Topologically decoherence-protected qubits with trapped ions
We show that trapped ions can be used to simulate a highly symmetrical
Hamiltonian with eingenstates naturally protected against local sources of
decoherence. This Hamiltonian involves long range coupling between particles
and provides a more efficient protection than nearest neighbor models discussed
in previous works. Our results open the perspective of experimentally realizing
in controlled atomic systems, complex entangled states with decoherence times
up to nine orders of magnitude longer than isolated quantum systems.Comment: 4 page
Directional beam pattern from a double metal quantum cascade laser with a TEM-horn antenna
Laser and microwave spectroscopy of even-parity Rydberg states of neutral ytterbium and Multichannel Quantum Defect Theory analysis
International audienceNew measurements of high-lying even parity 6sns 1 S0 and 6snd 3,1 D2 levels of neutral 174 Yb are presented in this paper. Spectroscopy is performed by a two-step laser excitation from the ground state 4f 14 6s 2 1 S0, and the Rydberg levels are detected by using the field ionization method. Additional two-photon microwave spectroscopy is used to improve the relative energy accuracy where possible. The spectroscopic measurements are complemented by a multichannel quantum defect theory (MQDT) analysis for the J=0 and the two-coupled J=2 even parity series. We compare our results with the previous analysis of Aymar et al [1] and analyze the observed differences. From the new MQDT models, a revised value for the first ionization limit I6s = 50443.07041(25) cm −1 is proposed
Beam shaping and ultrafast modulation of THz quantum cascade lasers
International audienc