0000000000385723

AUTHOR

Kalle S. U. Kansanen

0000-0002-3433-7926

showing 5 related works from this author

Theory for the stationary polariton response in the presence of vibrations

2019

We construct a model describing the response of a hybrid system where the electromagnetic field - in particular, surface plasmon polaritons - couples strongly with electronic excitations of atoms or molecules. Our approach is based on the input-output theory of quantum optics, and in particular it takes into account the thermal and quantum vibrations of the molecules. The latter is described within the $P(E)$ theory analogous to that used in the theory of dynamical Coulomb blockade. As a result, we are able to include the effect of the molecular Stokes shift on the strongly coupled response of the system. Our model then accounts for the asymmetric emission from upper and lower polariton mod…

DYNAMICSQuantum decoherenceFOS: Physical sciences02 engineering and technology01 natural sciencesplasmonicsvärähtelytQuantum mechanics0103 physical sciencesMesoscale and Nanoscale Physics (cond-mat.mes-hall)Polaritonhybrid quantum systemskvanttikemiaMOLECULE010306 general physicskvanttifysiikkaQuantumQuantum opticsPhysicsQuantum PhysicsCondensed Matter - Mesoscale and Nanoscale PhysicsSurface plasmonCoulomb blockade021001 nanoscience & nanotechnologySurface plasmon polaritonSURFACE-PLASMON POLARITONSpintailmiötLight emission0210 nano-technologyQuantum Physics (quant-ph)ENERGY-TRANSFERpolaritonsemissio (fysiikka)
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Polariton response in the presence of Brownian dissipation from molecular vibrations

2020

We study the elastic response of a stationarily driven system of a cavity field strongly coupled with molecular excitons, taking into account the main dissipation channels due to the finite cavity linewidth and molecular vibrations. We show that the frequently used coupled oscillator model fails in describing this response especially due to the non-Lorentzian dissipation of the molecules to their vibrations. Signatures of this failure are the temperature dependent minimum point of the polariton peak splitting, uneven polariton peak height at the minimum splitting, and the asymmetric shape of the polariton peaks even at the experimentally accessed "zero-detuning" point. Using a rather generi…

Field (physics)ExcitonGeneral Physics and AstronomyFOS: Physical sciencesPhysics::Optics010402 general chemistry01 natural sciencesMolecular physicsLaser linewidthmolecular vibrations0103 physical sciencesMesoscale and Nanoscale Physics (cond-mat.mes-hall)PolaritonPhysical and Theoretical ChemistrykvanttifysiikkapolaritonitBrownian motionPhysicsQuantum Physics010304 chemical physicsCondensed Matter - Mesoscale and Nanoscale PhysicsDissipationkvasihiukkaset0104 chemical sciences3. Good healthVibrationmolekyylifysiikkaMolecular vibrationQuantum Physics (quant-ph)
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Magnomechanics in suspended magnetic beams

2021

Cavity optomechanical systems have become a popular playground for studies of controllable nonlinear interactions between light and motion. Owing to the large speed of light, realizing cavity optomechanics in the microwave frequency range requires cavities up to several mm in size, hence making it hard to embed several of them on the same chip. An alternative scheme with much smaller footprint is provided by magnomechanics, where the electromagnetic cavity is replaced by a magnet undergoing ferromagnetic resonance, and the optomechanical coupling originates from magnetic shape anisotropy. Here, we consider the magnomechanical interaction occurring in a suspended magnetic beam -- a scheme in…

Quantum PhysicsCondensed Matter - Mesoscale and Nanoscale PhysicsFOS: Physical sciencesPhysics::Optics02 engineering and technology021001 nanoscience & nanotechnologymagneettikentät01 natural sciencestiiviin aineen fysiikka0103 physical sciencesMesoscale and Nanoscale Physics (cond-mat.mes-hall)010306 general physics0210 nano-technologyQuantum Physics (quant-ph)kvanttifysiikka
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Theory for polaritonic quantum tunneling

2022

I investigate the tunneling decay rate of a polaritonic system formed by a strong coupling between a vacuum cavity mode and $N$ metastable systems. Using a simple model potential, I find the instanton solutions controlling the low-temperature tunneling rate. The resulting rate modification due to the cavity is proportional to the mean of the second power of the light-matter coupling. No collective effect that would enhance the rates by a factor of $\sqrt{N}$ is present, which is in line with the results in the thermal activation regime.

Chemical Physics (physics.chem-ph)Quantum PhysicsPhysics - Chemical PhysicsFOS: Physical scienceskvanttimekaniikkaQuantum Physics (quant-ph)kvanttifysiikkapolaritonit
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Cavity-induced bifurcation in classical rate theory

2022

We show how coupling an ensemble of bistable systems to a common cavity field affects the collective stochastic behavior of this ensemble. In particular, the cavity provides an effective interaction between the systems, and parametrically modifies the transition rates between the metastable states. We predict that the cavity induces a collective phase transition at a critical temperature which depends linearly on the number of systems. It shows up as a spontaneous symmetry breaking where the stationary states of the bistable system bifurcate. We observe that the transition rates slow down independently of the phase transition, but the rate modification vanishes for alternating signs of the …

Chemical Physics (physics.chem-ph)Quantum PhysicsStatistical Mechanics (cond-mat.stat-mech)Physics - Chemical PhysicsFOS: Physical sciencesPhysics::OpticsQuantum Physics (quant-ph)Condensed Matter - Statistical Mechanics
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