Search results for "kvanttimekaniikka"
showing 10 items of 44 documents
Clauser-Horne-Shimony-Holt Bell inequality test in an optomechanical device
2018
We propose here a scheme, based on the measurement of quadrature phase coherence, aimed at testing the Clauser-Horne-Shimony-Holt Bell inequality in an optomechanical setting. Our setup is constituted by two optical cavities dispersively coupled to a common mechanical resonator. We show that it is possible to generate EPR-like correlations between the quadratures of the output fields of the two cavities, and, depending on the system parameters, to observe the violation of the Clauser-Horne-Shimony-Holt inequality.
Magnetoelectric effects in superconductors due to spin-orbit scattering : Nonlinear σ-model description
2021
We suggest a generalization of the nonlinear σ model for diffusive superconducting systems to account for magnetoelectric effects due to spin-orbit scattering. In the leading orders of spin-orbit strength and gradient expansion, it includes two additional terms responsible for the spin-Hall effect and the spin-current swapping. First, assuming a delta-correlated disorder, we derive the terms from the Keldysh path integral representation of the generating functional. Then we argue phenomenologically that they exhaust all invariants allowed in the effective action to the leading order in the spin-orbit coupling (SOC). Finally, the results are confirmed by a direct derivation of the saddle-poi…
Unique continuation property and Poincar�� inequality for higher order fractional Laplacians with applications in inverse problems
2020
We prove a unique continuation property for the fractional Laplacian $(-\Delta)^s$ when $s \in (-n/2,\infty)\setminus \mathbb{Z}$. In addition, we study Poincar\'e-type inequalities for the operator $(-\Delta)^s$ when $s\geq 0$. We apply the results to show that one can uniquely recover, up to a gauge, electric and magnetic potentials from the Dirichlet-to-Neumann map associated to the higher order fractional magnetic Schr\"odinger equation. We also study the higher order fractional Schr\"odinger equation with singular electric potential. In both cases, we obtain a Runge approximation property for the equation. Furthermore, we prove a uniqueness result for a partial data problem of the $d$-…
Contextuality Analysis of the Double Slit Experiment (With a Glimpse Into Three Slits)
2018
The Contextuality-by-Default theory is illustrated on contextuality analysis of the idealized double-slit experiment. The experiment is described by a system of contextually labeled binary random variables each of which answers the question: has the particle hit the detector, having passed through a given slit (left or right) in a given state (open or closed)? This system of random variables is a cyclic system of rank 4, formally the same as the system describing the EPR/Bell paradigm with signaling. Unlike the latter, however, the system describing the double-slit experiment is always noncontextual, i.e., the context-dependence in it is entirely explainable in terms of direct influences of…
Current Rectification in Junctions with Spin-Split Superconductors
2022
Spin-split superconductors exhibit an electron-hole asymmetric spin-resolved density of states, but the symmetry is restored upon averaging over spin. On the other hand, asymmetry appears again in tunneling junctions of spin-split superconductors with a spin-polarized barrier. As demonstrated recently in both theory and experiment, this fact leads to a particularly strong thermoelectric effect in superconductor-ferromagnet structures. In this work we show another important effect stemming from the electron-hole asymmetry: current rectification. We calculate the charge current in spin-polarized tunnel junctions of a normal metal and a spin-split superconductor with ac and dc voltage bias. In…
Absence of mutual polariton scatterings for strongly coupled surface plasmon polaritons and dye molecules with large Stokes shift
2013
The understanding and control of the dynamics of hybrid modes consisting of strongly coupled surface plasmon polaritons and molecular excitations of dye molecules is of great timely interest, as it allows one to tailor interactions between optical signals as needed for active all-optical devices. Here we utilize dye molecules with an especially large Stokes shift to demonstrate the absence of mutual scatterings among the strongly coupled hybrid modes. We employ a quantum mechanical three-level model and show that the hybrid modes decay via dephasing and internal relaxation of the molecules to a fluorescing state of the dye, which can be used as a measure for the decay. Our results provide e…
Shell Model Description of Spin-Dependent Elastic and Inelastic WIMP Scattering off 119Sn and 121Sb
2022
In this work, we calculate the spin structure functions for spin-dependent elastic and inelastic WIMP scattering off 119Sn and 121Sb. Estimates for detection rates are also given. 119Sn and 121Sb are amenable to nuclear structure calculations using the nuclear shell model (NSM). With the possible exception of 201Hg, they are the only such nuclei still unexplored theoretically for their potential of inelastic WIMP scattering to a very low excited state. The present calculations were conducted using a state-of-the-art WIMP–nucleus scattering formalism, and the available effective NSM two-body interactions describe the spectroscopic properties of these nuclei reasonably well. Structure functio…
Spin and charge currents driven by the Higgs mode in high-field superconductors
2020
The Higgs mode in superconducting materials describes slowly decaying oscillations of the order parameter amplitude. We demonstrate that in superconductors with a built-in spin-splitting field the Higgs mode is strongly coupled to the spin degrees of freedom, allowing for the generation of time-dependent spin currents. Converting such spin currents to electric signals by spin-filtering elements provides a tool for the second-harmonic generation and the electrical detection of the Higgs mode generated by the external irradiation. The nonadiabatic spin torques generated by these spin currents allow for the magnetic detection of the Higgs mode by measuring the precession of the magnetic moment…
K-kertaisesti kiellettyjen uniikkien β-siirtymien faasiavaruusintegraalit
2018
Tässä tutkimuksessa perehdytään K-kertaisesti kiellettyjen uniikkien beetasiirtymien faasiavaruusintegraaleihin. K-kertaisesti kielletyt uniikit beetasiirtymät ovat beetahajoamisten alaryhmä, ja faasiavaruusintegraalit kuvaavat hajoamisreaktion jälkeisiä lopputiloja ja antavat muun muassa tärkeää tietoa siirtymän hajoamisvakiosta. Tutkimuksessa laskettiin numeerisesti faasiavaruusintegraalit useille tunnetuille beetasiirtymille, jotka voivat olla kaksi- tai useampikertaisesti kiellettyjä. Saatua laskentadataa analysoitiin eri näkökulmista. Tärkein näkökulma on kielletyn uniikin beetasiirtymän ja samaa beetahajoamista kuvaavan perus- eli sallitun siirtymän välinen suhde, koska tämä näkökulma…
Asymptotic theory of resonant tunneling in quantum waveguides of variable cross-section
2008
Halkaisijaltaan muunnellun kvanttiaaltojohtimen kapenemat toimivat tehokkaina potentiaalivalleina elektronin pitkittäissuuntaiselle liikkeelle. Kaksi kapenemaa muodostaa kvanttiresonaattorin, jossa resonoiva tunnelointi voi tapahtua. Tämä tarkoittaa sitä, että elektronit, joiden energia on lähellä resonanssia, läpäisevät resonaattorin todennäköisyydellä lähellä yhtä.Sarafanov kuvailee väitöskirjassaan asymptoottisesti elektroniaallon etenemistä kvanttiaaltojohtimessa, jossa on kaksi kapenemaa. Aaltoluvun k oletetaan olevan ensimmäisen ja toisen kynnysluvun välissä, jolloin vain sisään tuleva ja poismenevä aalto voivat edetä jokaisessa aaltojohtimen päässä äärettömyydessä. Väitöskirjassa esi…