Lukas Novotny

Last Name

Novotny

First Name

Lukas

ORCID

0000-0002-9970-8345

Organisational unit

03944 - Novotny, Lukas / Novotny, Lukas

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Publications1 - 10 of 102

Electrically Tunable Graphene Organic Hybrid Ring Resonators
Ma, Ping; Zhang, X.Z.; Heni, Wolfgang; et al. (2021)
2021 IEEE Photonics Conference (IPC)
Quantum engineers in high demand
Rainò, Gabriele; Novotny, Lukas; Frimmer, Martin (2021)
Nature Materials
Gabriele Raino, Lukas Novotny and Martin Frimmer discuss the approach they are pursuing at ETH Zurich to provide students with an education in quantum engineering.
Cavity-mediated long-range interactions in levitated optomechanics
Vijayan, Jayadev; Piotrowski, Johannes; Gonzalez-Ballestero, Carlos; et al. (2023)
arXiv
The ability to engineer cavity-mediated interactions has emerged as a powerful tool for the generation of non-local correlations and the investigation of non-equilibrium phenomena in many-body systems. Levitated optomechanical systems have recently entered the multi-particle regime, with promise for using arrays of massive strongly coupled oscillators for exploring complex interacting systems and sensing. Here, by combining advances in multi-particle optical levitation and cavity-based quantum control, we demonstrate, for the first time, programmable cavity-mediated interactions between nanoparticles in vacuum. The interaction is mediated by photons scattered by spatially separated particles in a cavity, resulting in strong coupling ($G_\text{zz}/Ω_\text{z} = 0.238\pm0.005$) that does not decay with distance within the cavity mode volume. We investigate the scaling of the interaction strength with cavity detuning and inter-particle separation, and demonstrate the tunability of interactions between different mechanical modes. Our work paves the way towards exploring many-body effects in nanoparticle arrays with programmable cavity-mediated interactions, generating entanglement of motion, and using interacting particle arrays for optomechanical sensing.
Raman Scattering Cross Section of Confined Carbyne
Tschannen, Cla Duri; Gordeev, Georgy; Reich, Stephanie; et al. (2020)
Nano Letters
We experimentally quantify the Raman scattering from individual carbyne chains confined in double-walled carbon nanotubes. We find that the resonant differential Raman cross section of confined carbyne is on the order of 10−22 cm2 sr−1 per atom, making it the strongest Raman scatterer ever reported.
Optomechanical sideband asymmetry explained by stochastic electrodynamics
Novotny, Lukas; Frimmer, Martin; Militaru, Andrei; et al. (2022)
Physical Review A
Within the framework of stochastic electrodynamics we derive the noise spectrum of a laser beam reflected from a suspended mirror. The electromagnetic field follows Maxwell's equations and is described by a deterministic part that accounts for the laser field and a stochastic part that accounts for thermal and zero-point background fluctuations. Likewise, the mirror motion satisfies Newton's equation of motion and is composed of deterministic and stochastic parts, similar to a Langevin equation. We consider a photodetector that records the power of the field reflected from the mirror interfering with a frequency-shifted reference beam (heterodyne interferometry). We theoretically show that the power spectral density of the photodetector signal is composed of four parts: (i) a deterministic term with beat notes, (ii) shot noise, (iii) the actual heterodyne signal of the mirror motion, and (iv) a cross term resulting from the correlation between measurement noise (shot noise) and backaction noise (radiation pressure shot noise). The latter gives rise to the Raman sideband asymmetry observed with ultracold atoms, cavity optomechanics, and with levitated nanoparticles. Our classical theory fully reproduces experimental observations and agrees with the results obtained by a quantum theoretical treatment.
Electrical excitation of self-hybridized exciton polaritons in a van der Waals antiferromagnet
Ziegler, Jonas D.; Papadopoulos, Sotirios; Moilanen, Antti J.; et al. (2025)
Science Advances
The coupling of light with excitations in matter is one of the most important concepts to make photons interact, crucial for the development of efficient optoelectronic devices. In materials with exceptionally strong light-matter interaction, excitons can hybridize with photons without the need of an external cavity. Here, we report the electrical excitation of such self-hybridized polaritons in the van der Waals antiferromagnet CrSBr. We exploit an unconventional excitation via energy transfer from tunneling electrons in graphene tunnel junctions to strongly bound excitons in proximate CrSBr layers. This enables us to excite CrSBr crystals ranging in thickness from a bilayer up to 250 nanometers, with the strong linear polarization of the electroluminescence confirming the excitonic origin. We assign the electrically excited emission to self-hybridized exciton polaritons, highlighting the strong coupling between optical excitations and confined photon modes in CrSBr. Our findings not only offer an efficient method to generate polaritons electrically but also create opportunities for future spintronic devices.
Scalable all-optical cold damping of levitated nanoparticles
Vijayan, Jayadev; Zhang, Zhao; Piotrowski, Johannes; et al. (2023)
Nature Nanotechnology
Motional control of levitated nanoparticles relies on either autonomous feedback via a cavity or measurement-based feedback via external forces. Recent demonstrations of the measurement-based ground-state cooling of a single nanoparticle employ linear velocity feedback, also called cold damping, and require the use of electrostatic forces on charged particles via external electrodes. Here we introduce an all-optical cold damping scheme based on the spatial modulation of trap position, which has the advantage of being scalable to multiple particles. The scheme relies on programmable optical tweezers to provide full independent control over the trap frequency and position of each tweezer. We show that the technique cools the centre-of-mass motion of particles along one axis down to 17 mK at a pressure of 2 × 10−6 mbar and demonstrate its scalability by simultaneously cooling the motion of two particles. Our work paves the way towards studying quantum interactions between particles; achieving three-dimensional quantum control of particle motion without cavity-based cooling, electrodes or charged particles; and probing multipartite entanglement in levitated optomechanical systems.
Radiation damping of a Rayleigh scatterer illuminated by a linearly polarized plane wave
Abbassi, Mohammad Ali; Novotny, Lukas (2024)
Physical Review A
We investigate the radiation damping experienced by a dielectric spherical particle when it is illuminated by an electromagnetic plane wave within the Rayleigh regime. We derive the equivalent electric dipole of the moving particle and subsequently calculate the electromagnetic force acting on it from two different approaches. In the first approach, we calculate the force from the integration of stress tensor and field momentum. In the second one, we calculate the force directly from the integration of the force density. Our derivations reveal that the damping coefficient is equal to 6Pscat/mc2 along the propagation direction, whereas it is Pscat/mc2 along perpendicular directions. Here, Pscat denotes the power scattered by the particle, and mc2 represents the particle’s mass energy. The radiation damping derived in this paper sets upper limits on the quality factor of optically levitated objects and ensures the existence of a steady-state solution of the particle’s dynamics.
Van der Waals Photodetector with an Integrated WS₂ Light-Harvesting Antenna
Koyaz, Yesim; Papadopoulos, Sotirios; Moilanen, Antti J.; et al. (2025)
ACS Photonics
The responsivity of graphene-based photodetectors can be improved by forming heterostructures with other 2D materials and by further coupling to nanoparticles or quantum dots. In this study, we demonstrate that the photoresponse of a Graphene/MoSe₂/Graphene photodetector can be further enhanced by an external WS₂ bilayer acting as a light-harvesting antenna. The WS₂ bilayer is positioned outside the electronic pathway; thus, it does not directly contribute any photoexcited carriers. However, we observe a responsivity enhancement of up to 18 times, which can be explained by energy transfer from WS₂ to graphene and the MoSe₂ layer. Harnessing the excitonic properties of transition metal dichalcogenides (TMDs) as optical antennas defines a new strategy for photodetection.
Nonlinear Dark-Field Microscopy
Harutyunyan, Hayk; Palomba, Stefano; Renger, Jan; et al. (2010)
Nano Letters
Dark-field microscopy is a background-free imaging method that provides high sensitivity and a large signal-to-noise ratio. It finds application in nanoscale detection, biophysics and biosensing, particle tracking, single molecule spectroscopy, X-ray imaging, and failure analysis of materials. In dark-field microscopy, the unscattered light path is typically excluded from the angular range of signal detection. This restriction reduces the numerical aperture and affects the resolution. Here we introduce a nonlinear dark-field scheme that overcomes this restriction. Two laser beams of frequencies ω1 and ω2 are used to illuminate a sample surface and to generate a purely evanescent field at the four-wave mixing (4WM) frequency ω4wm = 2ω1 − ω2. The evanescent 4WM field scatters at sample features and generates radiation that is detected by standard far-field optics. This nonlinear dark-field scheme works with samples of any material and is compatible with applications ranging from biological imaging to failure analysis.© 2010 American Chemical Society.

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Lukas Novotny

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