Physikhttp://kops.uni-konstanz.de:80/handle/123456789/102020-11-27T03:50:29Z2020-11-27T03:50:29ZTunable sub-10-fs ultraviolet pulses generated by achromatic frequency doublingBaum, Peterpop518647Lochbrunner, StefanRiedle, Eberhard123456789/519342020-11-26T14:43:26Z2004-07-15Tunable sub-10-fs ultraviolet pulses generated by achromatic frequency doubling
Baum, Peter; Lochbrunner, Stefan; Riedle, Eberhard
Tunable UV pulses shorter than 10 fs are generated by achromatic frequency doubling of a noncollinear optical parametric amplifier. With a suitable two-prism sequence we achieve first- and second-order achromatic phase matching and increase the natural bandwidth of the nonlinear crystal by a factor of 80. Extremely broad UV spectra with a Fourier limit of 2.9 fs are generated in a 360-microm-thick beta-barium borate crystal at a conversion efficiency of 20%. We compensate for the angular dispersion and the first-order chirp of the highly stable UV pulses with a second prism sequence and fully characterize the temporal pulse shape with zero-additional-phase spectral phase interferometry for direct electric-field reconstruction (ZAP-SPIDER). Pulses as short as 7 fs are generated by controlling the higher-order chirp with a deformable mirror.
2004-07-15Baum, PeterLochbrunner, StefanRiedle, Eberhard530Tunable UV pulses shorter than 10 fs are generated by achromatic frequency doubling of a noncollinear optical parametric amplifier. With a suitable two-prism sequence we achieve first- and second-order achromatic phase matching and increase the natural bandwidth of the nonlinear crystal by a factor of 80. Extremely broad UV spectra with a Fourier limit of 2.9 fs are generated in a 360-microm-thick beta-barium borate crystal at a conversion efficiency of 20%. We compensate for the angular dispersion and the first-order chirp of the highly stable UV pulses with a second prism sequence and fully characterize the temporal pulse shape with zero-additional-phase spectral phase interferometry for direct electric-field reconstruction (ZAP-SPIDER). Pulses as short as 7 fs are generated by controlling the higher-order chirp with a deformable mirror.Optical Society of America (OSA)JOURNAL_ARTICLEeng10.1364/ol.29.0016860146-95921539-4794168616882914Optics Letters2020-11-26T15:43:26+01:00123456789/41Optics Letters ; 29 (2004), 14. - S. 1686-1688. - Optical Society of America (OSA). - ISSN 0146-9592. - eISSN 1539-4794true2020-11-26T14:43:26ZSpin waves in skyrmionic structures with various topological chargesRózsa, Leventepop528050Weißenhofer, Markuspop518432Nowak, Ulrichpop209772123456789/519322020-11-26T14:28:51Z2020-10-22Spin waves in skyrmionic structures with various topological charges
Rózsa, Levente; Weißenhofer, Markus; Nowak, Ulrich
Equilibrium properties and localised magnon excitations are investigated in topologically distinct skyrmionic textures. The observed shape of the structures and their orientation on the lattice is explained based on their vorticities and the symmetry of the crystal. The transformation between different textures and their annihilation as a function of magnetic field is understood based on the energy differences between them. The angular momentum spin-wave eigenmodes characteristic of cylindrically symmetric structures are combined in the distorted spin configurations, leading to avoided crossings in the magnon spectrum. The susceptibility of the skyrmionic textures to homogeneous external fields is calculated, revealing that a high number of modes become detectable due to the hybridization between the angular momentum eigenmodes. These findings should contribute to the observation of spin waves in distorted skyrmionic structures via experiments and numerical simulations, widening the range of their possible applications in magnonic devices.
2020-10-22Rózsa, LeventeWeißenhofer, MarkusNowak, Ulrich530Equilibrium properties and localised magnon excitations are investigated in topologically distinct skyrmionic textures. The observed shape of the structures and their orientation on the lattice is explained based on their vorticities and the symmetry of the crystal. The transformation between different textures and their annihilation as a function of magnetic field is understood based on the energy differences between them. The angular momentum spin-wave eigenmodes characteristic of cylindrically symmetric structures are combined in the distorted spin configurations, leading to avoided crossings in the magnon spectrum. The susceptibility of the skyrmionic textures to homogeneous external fields is calculated, revealing that a high number of modes become detectable due to the hybridization between the angular momentum eigenmodes. These findings should contribute to the observation of spin waves in distorted skyrmionic structures via experiments and numerical simulations, widening the range of their possible applications in magnonic devices.Institute of Physics PublishingJOURNAL_ARTICLEeng10.1088/1361-648X/abc4040953-89841361-648X335Journal of physics: Condensed matter2020-11-26T15:28:51+01:00123456789/41Journal of physics: Condensed matter ; 33 (2020), 5. - 054001. - Institute of Physics Publishing. - ISSN 0953-8984. - eISSN 1361-648Xtrue2020-11-26T14:28:51ZOctave wide tunable UV-pumped NOPA : pulses down to 20 fs at 0.5 MHzrepetition rateHomann, ChristianSchriever, ChristianBaum, Peterpop518647Riedle, Eberhard123456789/519202020-11-25T14:10:18Z2008Octave wide tunable UV-pumped NOPA : pulses down to 20 fs at 0.5 MHzrepetition rate
Homann, Christian; Schriever, Christian; Baum, Peter; Riedle, Eberhard
Femtosecond laser pulses, which are tunable from 440 to 990 nm, are generated at MHz repetition rates by noncollinear parametric amplification (NOPA). The pulses have durations of 20 to 30 fs over the major part of the tuning range and a high energy stability of 1.3% (rms). The NOPA is pumped with ultraviolet pulses from the third harmonic of an ytterbium doped fiber laser system and seeded by a smooth continuum generated in bulk sapphire. The residual second harmonic is used to pump an additional NOPA, which is independently tunable from 620 to 990 nm. Interference experiments show that the two NOPA systems have a precisely locked relative phase, despite of being pumped by different harmonics with a random phase jitter. This demonstrates that the phase of pulses generated by optical parametric amplification does not depend on the pump phase.
2008Homann, ChristianSchriever, ChristianBaum, PeterRiedle, Eberhard530Femtosecond laser pulses, which are tunable from 440 to 990 nm, are generated at MHz repetition rates by noncollinear parametric amplification (NOPA). The pulses have durations of 20 to 30 fs over the major part of the tuning range and a high energy stability of 1.3% (rms). The NOPA is pumped with ultraviolet pulses from the third harmonic of an ytterbium doped fiber laser system and seeded by a smooth continuum generated in bulk sapphire. The residual second harmonic is used to pump an additional NOPA, which is independently tunable from 620 to 990 nm. Interference experiments show that the two NOPA systems have a precisely locked relative phase, despite of being pumped by different harmonics with a random phase jitter. This demonstrates that the phase of pulses generated by optical parametric amplification does not depend on the pump phase.Optical Society of America (OSA)JOURNAL_ARTICLEeng10.1364/OE.16.0057461094-408757465756168Optics Express2020-11-25T15:10:18+01:00123456789/41Optics Express ; 16 (2008), 8. - S. 5746-5756. - Optical Society of America (OSA). - eISSN 1094-4087true2020-11-25T14:10:18ZSpin shuttling in a silicon double quantum dotGinzel, Florianpop247684Mills, Adam R.Petta, Jason R.Burkard, Guidopop205895123456789/519172020-11-25T12:52:23Z2020-07-07T16:33:06ZSpin shuttling in a silicon double quantum dot
Ginzel, Florian; Mills, Adam R.; Petta, Jason R.; Burkard, Guido
The transport of quantum information between different nodes of a quantum device is among the challenging functionalities of a quantum processor. In the context of spin qubits, this requirement can be met by coherent electron spin shuttling between semiconductor quantum dots. Here we theoretically study a minimal version of spin shuttling between two quantum dots. To this end, we analyze the dynamics of an electron during a detuning sweep in a silicon double quantum dot (DQD) occupied by one electron. Possibilities and limitations of spin transport are investigated. Spin-orbit interaction and the Zeeman effect in an inhomogeneous magnetic field play an important role for spin shuttling and are included in our model. Interactions that couple the position, spin, and valley degrees of freedom open a number of avoided crossings in the spectrum allowing for diabatic transitions and interfering paths. The outcomes of single and repeated spin shuttling protocols are explored by means of numerical simulations and an approximate analytical model based on the solution of the Landau-Zener problem. We find that a spin infidelity as low as 1−F<sub>s</sub>≲0.002 with a relatively fast level velocity of α=600μeVns<sup>−1</sup> is feasible for optimal choices of parameters or by making use of constructive interference.
2020-07-07T16:33:06ZGinzel, FlorianMills, Adam R.Petta, Jason R.Burkard, Guido530The transport of quantum information between different nodes of a quantum device is among the challenging functionalities of a quantum processor. In the context of spin qubits, this requirement can be met by coherent electron spin shuttling between semiconductor quantum dots. Here we theoretically study a minimal version of spin shuttling between two quantum dots. To this end, we analyze the dynamics of an electron during a detuning sweep in a silicon double quantum dot (DQD) occupied by one electron. Possibilities and limitations of spin transport are investigated. Spin-orbit interaction and the Zeeman effect in an inhomogeneous magnetic field play an important role for spin shuttling and are included in our model. Interactions that couple the position, spin, and valley degrees of freedom open a number of avoided crossings in the spectrum allowing for diabatic transitions and interfering paths. The outcomes of single and repeated spin shuttling protocols are explored by means of numerical simulations and an approximate analytical model based on the solution of the Landau-Zener problem. We find that a spin infidelity as low as 1−F<sub>s</sub>≲0.002 with a relatively fast level velocity of α=600μeVns<sup>−1</sup> is feasible for optimal choices of parameters or by making use of constructive interference.American Physical Society (APS)JOURNAL_ARTICLEeng10.1103/PhysRevB.102.1954182469-99502469-996910219Physical Review B2020-11-25T13:52:23+01:00123456789/41Physical Review B ; 102 (2020), 19. - 195418. - American Physical Society (APS). - ISSN 2469-9950. - eISSN 2469-9969true2020-11-25T12:52:23Ztrue