اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThe Spectrum of Quasistable States in a Strong Microwave Field
48
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
When atoms are exposed to intense laser or microwave pulses ~10% of the atoms are found in Rydberg states subsequent to the pulse, even if it is far more intense than required for static field ionization. The optical spectra of the surviving Li atoms in the presence of a 38 GHz microwave field suggest how atoms survive an intense pulse. The spectra exhibit a periodic train of peaks 38 GHz apart. One peak is just below the limit, and with a 90 V/cm field amplitude the train extends from 300 GHz above the limit to 3000 GHz below it. The spectra and quantum mechanical calculations imply that the atoms survive in quasi stable states in which the Rydberg electron is in a weakly bound orbit infrequently returning to the ionic core during the intense pulse.
قيم البحث
اقرأ أيضاً
The discovery of $Xi_{cc}^{++}$ by the LHCb Collaboration triggers predictions of more doubly charmed baryons. By taking into account both the $P$-wave excitations between the two charm quarks and the scattering of light pseudoscalar mesons off the g
round state doubly charmed baryons, a set of negative-parity spin-1/2 doubly charmed baryons are predicted already from a unitarized version of leading order chiral perturbation theory. Moreover, employing heavy antiquark-diquark symmetry the relevant low-energy constants in the next-to-leading order are connected with those describing light pseudoscalar mesons scattering off charmed mesons, which have been well determined from lattice calculations and experimental data. Our calculations result in a spectrum richer than that of heavy mesons. We find two very narrow $J^P=1/2^-$ $Omega_{cc}^P$, which very likely decay into $Omega_{cc}pi^0$ breaking isospin symmetry. In the isospin-1/2 $Xi_{cc}^P$ sector, three states are predicted to exist below 4.2~GeV with the lowest one being narrow and the other two rather broad. We suggest to search for the $Xi_{cc}^{P}$ states in the $Xi_{cc}^{++}pi^-$ mode. Searching for them and their analogues are helpful to establish the hadron spectrum.
We present a field theoretical model of point-form dynamics which exhibits resonance scattering. In particular, we construct point-form Poincare generators explicitly from field operators and show that in the vector spaces for the in-states and out-s
tates (endowed with certain analyticity and topological properties suggested by the structure of the $S$-matrix) these operators integrate to furnish differentiable representations of the causal Poincare semigroup, the semidirect product of the semigroup of spacetime translations into the forward lightcone and the group of Lorentz transformations. We also show that there exists a class of emph{irreducible} representations of the Poincare semigroup defined by a complex mass and a half-integer spin. The complex mass characterizing the representation naturally appears in the construction as the square root of the pole position of the propagator. These representations provide a description of resonances in the same vein as Wigners unitary irreducible representations of the Poincare group provide a description of stable particles.
High harmonic spectra show that laser-induced strong field ionization of water has a significant contribution from an inner-valence orbital. Our experiment uses the ratio of H2O and D2O high harmonic yields to isolate the characteristic nuclear motio
n of the molecular ionic states. The nuclear motion initiated via ionization of the highest occupied molecular orbital (HOMO) is small and is expected to lead to similar harmonic yields for the two isotopes. In contrast, ionization of the second least bound orbital (HOMO-1) exhibits itself via a strong bending motion which creates a significant isotope effect. We elaborate on this interpretation by simulating strong field ionization and high harmonic generation from the water isotopes using the time-dependent Schrodinger equation. We expect that this isotope marking scheme for probing excited ionic states in strong field processes can be generalized to other molecules.
We study electromagnetically induced transparency (EIT) in the 5s$rightarrow$5p$rightarrow$46s ladder system of a cold $^{87}$Rb gas. We show that the resonant microwave coupling between the 46s and 45p states leads to an Autler-Townes splitting of t
he EIT resonance. This splitting can be employed to vary the group index by $pm 10^5$ allowing independent control of the propagation of dark state polaritons. We also demonstrate that microwave dressing leads to enhanced interaction effects. In particular, we present evidence for a $1/R^3$ energy shift between Rydberg states resonantly coupled by the microwave field and the ensuing breakdown of the pair-wise interaction approximation.
The problem of time delay in tunneling ionization is revisited. The origin of time delay at the tunnel exit is analysed, underlining the two faces of the concept of the tunnelling time delay: the time delay around the tunnel exit and the asymptotic t
ime delay at a detector. We show that the former time delay, in the sense of a delay in the peak of the wavefunction, exists as a matter of principle and arises due to the sub-barrier interference of the reflected and transmitted components of the tunneling electronic wavepacket. We exemplify this by describing the tunnelling ionization of an electron bound by a short-range potential within the strong field approximation in a deep tunnelling regime. If sub-barrier reflections are extracted from this wavefunction, then the time delay of the peak is shown to vanish. Thus, we assert that the disturbance of the tunnelling wavepacket by the reflection from the surface of the barrier causes a time delay in the neighbourhood of the tunnel exit.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
