We consider a harmonic oscillator (HO) with a time-dependent frequency which undergoes two successive abrupt changes. By assumption, the HO starts in its fundamental state with frequency
ω
0
, then, ...at
t
= 0, its frequency suddenly increases to
ω
1
and, after a finite time interval
τ
, it comes back to its original value
ω
0
. Contrary to what one could naively think, this problem is quite a non-trivial one. Using algebraic methods, we obtain its exact analytical solution and show that at any time
t
> 0 the HO is in a vacuum squeezed state. We compute explicitly the corresponding squeezing parameter (SP) relative to the initial state at an arbitrary instant and show that, surprisingly, it exhibits oscillations after the first frequency jump (from
ω
0
to
ω
1
), remaining constant after the second jump (from
ω
1
back to
ω
0
). We also compute the time evolution of the variance of a quadrature. Last, but not least, we calculate the vacuum (fundamental state) persistence probability amplitude of the HO, as well as its transition probability amplitude for any excited state.
The outlines of the Glauber-Velasco (GV) and the Stochastic Vacuum models (SVM) for describing pp elastic scattering are presented. The amplitudes and the cross-sections of both models are ...investigated and compared at √s = 7TeV. The asymptotic energy behaviour for the SVM is also studied.
We investigate the resonance energy transfer (RET) rate between two quantum emitters near a suspended graphene sheet in vacuum under the influence of an external magnetic field. We perform the ...analysis for low and room temperatures and show that, due to the extraordinary magneto-optical response of graphene, it allows for an active control and tunability of the RET even in the case of room temperature. We also demonstrate that the RET rate is extremely sensitive to small variations of the applied magnetic field and can be tuned up to a striking six orders of magnitude for quite realistic values of magnetic field. Moreover, we highlight the fundamental role played by the magnetoplasmon polaritons supported by the graphene monolayer as the dominant channel for the RET within a certain distance range. Our results suggest that magneto-optical media may take the manipulation of energy transfer between quantum emitters to a whole new level and broaden even more its great spectrum of applications.
We theoretically investigate the quantum reflection of different atoms by two-dimensional (2D) materials of the graphene family (silicene, germanene, and stanene), subjected to an external electric ...field and circularly polarized light. By using Lifshitz theory to compute the Casimir-Polder potential, which ensures that our predictions apply to all regimes of atom-2D surface distances, we demonstrate that the quantum reflection probability exhibits distinctive, unambiguous signatures of topological phase transitions that occur in 2D materials. We also show that the quantum reflection probability can be highly tunable by these external agents, depending on the atom-surface combination, reaching a variation of 40% for rubidium in the presence of a stanene sheet. Our findings attest not only that dispersive forces play a crucial role in quantum reflection, but also that the topological phase transitions of the graphene family materials can be comprehensively and efficiently probed via atom-surface interactions at the nanoscale.
Contemporary medicine views health as the individual’s physical, mental, and social well-being. Oral health plays a crucial role in one’s well-being, as the oral cavity and its surrounding regions ...execute essential functions in verbal and nonverbal communication, sensing, digestion, and significantly contribute to aesthetic appearance. The multifaceted nature of the notion of oral health, as well as the patient’s needs and autonomous will result in various treatment options for the same oral state, favouring often contrasting ethical values and different aspects of oral health. The objective of this article is to suggest alternative treatment strategies in dentistry with respect to the following factors: extent of rehabilitation, preserving one’s anatomical structures, aesthetic outcome, number of sessions, patient autonomy. Additionally, this article describes the suggested treatment strategies in an ethical context and determines the conditions of their employment. The suggested treatment strategies are divided in two categories,
extensive treatment strategies
focusing on the patient’s entire craniofacial complex, while
specific treatment strategies
focus on specific paramount issues.
We investigate the spontaneous emission rate of a two-level quantum emitter next to a composite medium made of randomly distributed metallic inclusions embedded in a dielectric host matrix. In the ...near field, the Purcell factor can be enhanced by two orders of magnitude relative to the case of a homogeneous metallic medium and reaches its maximum precisely at the insulator-metal transition. By unveiling the role of the decay pathways in the emitter's lifetime, we demonstrate that, close to the percolation threshold, the radiation emission process is dictated by electromagnetic absorption in the heterogeneous medium. We show that our findings are robust against change in material properties and shape of inclusions and apply for different effective-medium theories as well as for a wide range of transition frequencies.
A measurement of the ratio of the branching fractions of the B(+) → K(+)μ(+)μ(-) and B(+) → K(+)e(+)e(-) decays is presented using proton-proton collision data, corresponding to an integrated ...luminosity of 3.0 fb(-1), recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. The value of the ratio of branching fractions for the dilepton invariant mass squared range 1 < q(2) < 6 GeV(2)/c(4) is measured to be 0.745(-0.074)(+0.090)(stat) ± 0.036(syst). This value is the most precise measurement of the ratio of branching fractions to date and is compatible with the standard model prediction within 2.6 standard deviations.
A
bstract
The isospin asymmetries of
B
→
Kμ
+
μ
−
and
B
→
K
*
μ
+
μ
−
decays and the partial branching fractions of the
B
0
→
K
0
μ
+
μ
−
,
B
+
→
K
+
μ
+
μ
−
and
B
+
→
K
*+
μ
+
μ
−
decays are ...measured as functions of the dimuon mass squared,
q
2
. The data used correspond to an integrated luminosity of 3 fb
−1
from proton-proton collisions collected with the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV in 2011 and 2012, respectively. The isospin asymmetries are both consistent with the Standard Model expectations. The three measured branching fractions favour lower values than their respective theoretical predictions, however they are all individually consistent with the Standard Model.
Resonant structures in B^{0}→ψ^{'}π^{-}K^{+} decays are analyzed by performing a four-dimensional fit of the decay amplitude, using pp collision data corresponding to 3 fb^{-1} collected with the ...LHCb detector. The data cannot be described with K^{+}π^{-} resonances alone, which is confirmed with a model-independent approach. A highly significant Z(4430)^{-}→ψ^{'}π^{-} component is required, thus confirming the existence of this state. The observed evolution of the Z(4430)^{-} amplitude with the ψ^{'}π^{-} mass establishes the resonant nature of this particle. The mass and width measurements are substantially improved. The spin parity is determined unambiguously to be 1^{+}.
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