Name: LEAPS meets Quantum Technology
Start: 2022-05-15T09:00:00+02:00
End: 2022-05-20T08:00:00+02:00
Location: Hotel Hermitage, La Biodola Bay, Elba Island, Italy

LEAPS meets Quantum Technology

from Sunday 15 May 2022 (09:00) to Friday 20 May 2022 (08:00)

Monday 9 May 2022
Tuesday 10 May 2022
Wednesday 11 May 2022
Thursday 12 May 2022
Friday 13 May 2022
Saturday 14 May 2022
Sunday 15 May 2022

18:00 REGISTRATION FOR DELEGATES
REGISTRATION FOR DELEGATES
18:00 - 19:00

19:00 WELCOME COCKTAIL
WELCOME COCKTAIL
19:00 - 20:00

20:00 DINNER
DINNER
20:00 - 21:00

Monday 16 May 2022
09:00 WELCOME - Massimo Ferrario (Istituto Nazionale di Fisica Nucleare) Helmut Dosch (DESY) Oliver Rader Leonid Rivkin
WELCOME
- Massimo Ferrario (Istituto Nazionale di Fisica Nucleare)
- Helmut Dosch (DESY)
- Oliver Rader
- Leonid Rivkin
09:00 - 09:30
09:30 Experiments at synchrotron and FEL sources for 2D materials science - Kai Rossnagel (DESY / CAU Kiel)
Experiments at synchrotron and FEL sources for 2D materials science
- Kai Rossnagel (DESY / CAU Kiel)
09:30 - 10:30
INSTRUMENTATION TUTORIAL
10:30 Coffee break
Coffee break
10:30 - 11:00
11:00 Topological materials science and quantum computing - Matthew Gilbert
Topological materials science and quantum computing
- Matthew Gilbert
11:00 - 12:00
TUTORIAL
12:00 Hybrid qubits - Andreas Wallraff (ETH Zurich)
Hybrid qubits
- Andreas Wallraff (ETH Zurich)
12:00 - 12:30
12:30 LUNCH BREAK
LUNCH BREAK
12:30 - 14:30
14:30 Materials science for quantum computing - Nathalie de Leon (Princeton University)
Materials science for quantum computing
- Nathalie de Leon (Princeton University)
14:30 - 15:30
TUTORIAL
15:30 Coffee break
Coffee break
15:30 - 15:45
15:45 Synchrotron Radiation Light Sources - Karsten Holldack (Helmholtz-Zentrum Berlin)
Synchrotron Radiation Light Sources
- Karsten Holldack (Helmholtz-Zentrum Berlin)
15:45 - 16:45
INSTRUMENTATION TUTORIAL
16:45 Coffee break
Coffee break
16:45 - 17:00
17:00 Quantum Materials research at SOLEIL - Amina TALEB-IBRAHIMI (Synchrotron SOLEIL)
Quantum Materials research at SOLEIL
- Amina TALEB-IBRAHIMI (Synchrotron SOLEIL)
17:00 - 17:20
17:20 Direct Insight into the Electronic Band Structure and Spin Properties of Novel Topological Materials - Ivana Vobornik (CNR-IOM)
Direct Insight into the Electronic Band Structure and Spin Properties of Novel Topological Materials
- Ivana Vobornik (CNR-IOM)
17:20 - 17:40
Photoemission with angular and spin resolution (Spin-ARPES) probes directly the electronic bands and their spin textures in solids. The development of the technique is closely related to, and stimulated by the development of novel quantum materials, often characterized by peculiar spin arrangements. We developed a highly efficient Spin-ARPES spectrometer [DOI:10.1107/S1600577517006907] hosted at the APE-LE beamline (Elettra/NFFA facilities), which became one of the reference European Spin-ARPES setups, heavily exploited in the investigation of novel candidate spintronic materials. Here I will show how we implemented Spin-ARPES in the investigation of Dirac semimetals that attract attention due to the considerable technological potential related to their nontrivial topological states and exotic quantum transport. Especially, materials hosting type-II Dirac fermions are expected to provide functionalities enabled by anisotropic optical and magnetotransport properties. Nevertheless, any practical implementation remained elusive so far since the Dirac point lies far from the Fermi level, limiting the technological exploitation. By means of spin-ARPES we found that kitkaite NiTeSe hosts both the type-II bulk Dirac fermions and the topological spin polarized surface states in close proximity of the Fermi level and this likely plays a role in the performance of NiTeSe-based microwave detector that was subsequently demonstrated [DOI:10.1002/adfm.202106101].
17:40 Ferromagnetic Resonance in a Nickel thin film driven by optically-excited Surface Acoustic Waves (SAWs) in a Transient Grating (TG) setup - Pietro Carrara (Università degli Studi di Milano)
Ferromagnetic Resonance in a Nickel thin film driven by optically-excited Surface Acoustic Waves (SAWs) in a Transient Grating (TG) setup
- Pietro Carrara (Università degli Studi di Milano)
17:40 - 18:00
Moore-ruled down-scaling of magnetic bits in new-generation memories hampers deterministic switching and calls for new techniques for magnetization manipulation. Acoustic control of magnetism is an appealing route for low-energy-consumption operation, e.g. exploiting magneto-elastic coupling (MEC) in a thin-film planar heterostructure, where SAWs at micron-size wavelength drive magnetization precession by inverse magnetostriction [1]. We studied MEC in Nickel films (8-40 nm) deposited on amorphous and crystalline substrates. We employed a four-wave-mixing approach [2] in a UHV-ready TG-spectroscopy setup, with a 300 fs, high frequency laser (NFFA-SPRINT*). Two pump pulses thermally excite SAWs, which couple to magnetostatic waves. A third time-delayed pulse acts either as acoustic (TG diffraction), or as magnetic probe (Faraday rotation). Tuning an external magnetic field, the condition of SAW-driven ferromagnetic resonance (FMR) is reached: the time-dependent magneto-elastic field balances the Gilbert damping, allowing spin precession to last long after its natural damping. The range of wavevectors studied (few inverse microns) allows a comparison with results from standard FMR in terms of Kittel curve and extrinsic contribution to the magnetic damping. *https://www.trieste.nffa.eu/techniques/spectroscopy/tg-sprint/ [1] W.Yang and H.Schmidt, Appl.Phys.Rev. 8, 021304 (2021) [2] J.Janušonis et al. Sci.Rep. 6.1, 1-10 (2016)
18:00 Ultrafast magnetic switching by resonant excitation of optical phonons - Andrei Kirilyuk
Ultrafast magnetic switching by resonant excitation of optical phonons
- Andrei Kirilyuk
18:00 - 18:20
Identifying an efficient pathway to change the order parameter via a subtle excitation of the coupled high-frequency mode is the ultimate goal of the field of ultrafast phase transitions. This is an especially interesting research direction in magnetism, where the coupling between spin and lattice excitations is required for magnetization reversal. Despite several attempts however, the switching between magnetic states via resonant pumping of phonon modes has yet to be demonstrated. To provide strong resonant excitation of the phonon modes, we use pulses from FELIX (Free Electron Laser for Infrared eXperiments, Nijmegen, The Netherlands). The IR/THz light with photon energy ranging between 25 meV and 124 meV (wavelength 10-50 $\mu$m) is typically used, with pulse energy between 20 $\mu$J in a single micropulse, and 150 $\mu$J using cavity-dumping. And thus we show how an ultrafast resonant excitation of LO phonons in magnetic garnet films switches magnetization into a peculiar quadrupolar magnetic domain pattern, unambiguously revealing the magneto-elastic mechanism of the switching. In contrast, the excitation of strongly absorbing TO modes results in thermal demagnetization only. The mechanism appears to be very universal, and is shown to work in samples with very different crystallographic symmetry and magnetic properties, such as antiferromagnets.
18:20 END OF SESSION
END OF SESSION
18:20 - 18:30
18:50 POSTER SESSION 1- cheese and wine
POSTER SESSION 1- cheese and wine
18:50 - 20:00
Contributions

18:50 Hyperdoped superconducting Ge for quantum technology - Shengqiang Zhou (Helmholtz-Zentrum Dresden-Rossendorf)

18:50 Fluorescence model for Nitrogen Vacancy Centers - Ivan Panadero Muñoz

18:50 Quantum control of two transmons with tunable coupling - Hilario Espinós Martínez (Universidad Carlos III, Madrid)

18:50 Dynamics of quantum correlations in two 2-level atoms coupling with thermal reservoirs - Zakaria Dahbi (Mohammed V University in Rabat, Morocco)

18:50 Optimization of in-situ growth of Al/InAs hybrid systems for the development of Andreev quantum computation - Kirti Magdhi (Consiglio Nazionale delle Ricerche, Istituto Officina dei Materiali)

18:50 A photonic platform hosting telecom photon emitters in silicon - Nagesh Shamrao Jagtap (Helmholtz-Zentrum Dresden-Rossendorf)

18:50 Tailoring oxide quantum materials by ion beam - Shengqiang Zhou (Helmholtz-Zentrum Dresden-Rossendorf)

18:50 Nanoscale mapping of strain variations in vicinity of Si/SiGe spin qubit devices by scanning X-ray diffraction microscopy - Carsten Richter (Institut für Kristallzüchtung)

18:50 Parameterized Quantum Supervised Learning Classifiers - Debanjan Konar
Tuesday 17 May 2022
09:00 Diamond NV-centers - Vadim Vorobev (3rd Physical Institute University of Stuttgat)
Diamond NV-centers
- Vadim Vorobev (3rd Physical Institute University of Stuttgat)
09:00 - 10:00
10:00 NV-centers and the quest for room temperature superconductors - Jean-Francois Roch
NV-centers and the quest for room temperature superconductors
- Jean-Francois Roch
10:00 - 10:30
10:30 Coffee break
Coffee break
10:30 - 11:00
11:00 Focused ion beam writing of scalable quantum emitters in silicon - Manfred Helm (Helmholtz-Zentrum Dresden-Rossendorf (HZDR)) Michael Hollenbach (Helmholtz-Zentrum Dresden-Rossendorf (HZDR))
Focused ion beam writing of scalable quantum emitters in silicon
- Manfred Helm (Helmholtz-Zentrum Dresden-Rossendorf (HZDR))
- Michael Hollenbach (Helmholtz-Zentrum Dresden-Rossendorf (HZDR))
11:00 - 11:20
Single-photon sources are one of the elementary building blocks for photonic quantum information and optical quantum computing [1]. One of the upcoming challenges is the monolithic photonic integration and coupling of single-photon emission, reconfigurable photonic elements and single-photon detection on a silicon chip in a controllable manner. Particularly, fully integrated single-photon emitters on-demand are required for enabling a smart integration of advanced functionalities in on-chip quantum photonic circuits [2]. This work presents a mask-free nanofabrication method involving a quasi-deterministic creation of scalable extrinsic color centers in silicon emitting in the optical telecom O-band [3] on a commercial silicon-on-insulator platform using focused ion beam writing. We also show the local writing of an intrinsic color center in silicon, which is linked to a tri-interstitial complex and reveals quantum emission close to the telecom band [4]. The successful integration of these telecom quantum emitters into photonic structures such as micro-resonators, nanopillars [5] and photonic crystals with sub-micrometer precision paves the way toward a monolithic, all-silicon-based semiconductor-superconductor quantum circuit. [1]D. D. Awschalom et al.,Nature Photonics 12,516 (2018) [2]J. C. Adcock et al.,IEEE, 27, 2, (2021) [3]M. Hollenbach et al.,Optics Express 28,26111 (2020) [4]Y. Baron et al.,arXiv:2108.04283 (2021) [5]M. Hollenbach et al.,arXiv:2112.02680 (2021)
11:20 Active Sites of Te in Hyperdoped Si by Hard X-ray Photoelectron Kikuchi-Diffraction - Moritz Hoesch (DESY Photon Science)
Active Sites of Te in Hyperdoped Si by Hard X-ray Photoelectron Kikuchi-Diffraction
- Moritz Hoesch (DESY Photon Science)
11:20 - 11:40
n-type doping of Si by the deep chalcogen donor Te in excess of the solubility limit was recently demonstrated to lead to hyperdoped material [1]. Our investigation by hard x-ray photoelectron spectroscopy (hXPS) reveals at least two different Te species with different binding energy and systematically varying concentrations with increasing ion implantation dose. At the highest doping we study the photoelectron scattering patterns using hard x-ray photoelectron diffraction (hXPD) [2]. Substitutional site occupation of both Te monomers as well as dimers is identified with increasing binding energy leading to the main features in the XPS spectra. The sharp hXPD patterns allow the detailed analysis of the local surrounding of the dopant atoms [3]. At the lowest binding energy, an additional species is found and the distinct, rather diffuse hXPD pattern at this binding energy suggests the assignment of this component to a small fraction of Te in clusters. References [1] M. Wang et al. Phys. Rev. Appl. 11 054039 (2019) and references therein. [2] O. Fedchenko et al NJP 21, 113031 (2019); [3] O. Fedchenko et al NJP 22, 103002 (2020).
11:40 Rydberg states and entanglement in the light of FEL THz radiation - Benedict Murdin
Rydberg states and entanglement in the light of FEL THz radiation
- Benedict Murdin
11:40 - 12:10
12:10 Magnetic Imaging at High Pressure inside Diamond Anvil Cells using Ensembles of Nitrogen-Vacancy Centers - Loïc Toraille (CEA, DAM, DIF, F-91297 Arpajon, France)
Magnetic Imaging at High Pressure inside Diamond Anvil Cells using Ensembles of Nitrogen-Vacancy Centers
- Loïc Toraille (CEA, DAM, DIF, F-91297 Arpajon, France)
12:10 - 12:30
The diamond anvil cell (DAC) is the tool that allows scientists to create pressures comparable to those existing in the Earth core, above the megabar. These conditions lead to new states of matter with specific magnetic and superconducting properties. However, the minute size of the sample and the constraints associated to the DAC make the implementation of magnetic diagnostics highly challenging. We will report the realization of an optical magnetometry technique that can detect the sample magnetic behavior through the diamond anvil, based on Nitrogen-Vacancy (NV) centers located at the surface of the anvil. The NV center has a spin-dependent photoluminescence. By combining a microwave excitation and an optical excitation/readout, we can reconstruct the full vector magnetic field inside the diamond anvil cell at pressures as high as 60 GPa so far. Furthermore, the relatively simplicity of the setup enables its transportation and use on a synchrotron beamline As a proof-of-principle, we detected the α-ε phase transition of iron with pressure through the monitoring of its magnetization, while simultaneously following the crystalline phase transition via X-ray diffraction. We will also report experiments performed on MgB2 that demonstrate the detection of a superconducting state through the observation of the Meissner effect.
12:30 LUNCH BREAK
LUNCH BREAK
12:30 - 14:30

14:30

14:30 - 15:30
15:30 Free electron lasers - Enrico Allaria (Elettra - Sincrotrone Trieste)
Free electron lasers
- Enrico Allaria (Elettra - Sincrotrone Trieste)
15:30 - 16:30
INSTRUMENTATION TUTORIAL B
16:30 Coffee break
Coffee break
16:30 - 17:00
17:00 Magnetic molecular qubits - Stefano Carretta (Istituto Nazionale di Fisica Nucleare)
Magnetic molecular qubits
- Stefano Carretta (Istituto Nazionale di Fisica Nucleare)
17:00 - 17:30
17:30 Thermal- and light-induced switching of spin-crossover complexes by XAS - Sangeeta Thakur (Freie University Berlin)
Thermal- and light-induced switching of spin-crossover complexes by XAS
- Sangeeta Thakur (Freie University Berlin)
17:30 - 18:00
18:00 EuPRAXIA: user’s opportunities and perspectives. - Massimo Ferrario (Istituto Nazionale di Fisica Nucleare)
EuPRAXIA: user’s opportunities and perspectives.
- Massimo Ferrario (Istituto Nazionale di Fisica Nucleare)
18:00 - 18:20
On the wake of the results obtained so far at the SPARC_LAB test-facility at LNF, we are currently in the process to design and build a new multi-disciplinary user-facility, equipped with a soft X-ray Free Electron Laser (FEL) driven by a ~1 GeV high brightness linac based on plasma accelerator modules. It is widely accepted by the international accelerator scientific community that a fundamental milestone towards the realization of a plasma driven future Linear Collider (LC) will be the integration of the new high gradient accelerating plasma modules in a FEL user facility (see the H2020 approved Design Study EuPRAXIA). This fundamental goal will be integrated in the LNF facility by using a high gradient X-band RF linac and the high power laser FLAME to drive Plasma Oscillations in the accelerator module. This activity is performed in the framework of the EuPRAXIA design study. In this talk we report about the recent progresses in the on going design study of the new facility and about opportunities and perspectives for international FEL user community.
18:20 Opportunities to unravel the electronic and structural properties of quantum materials and complex nanostructures on femtosecond time scales at the European XFEL - Andreas Scherz (European XFEL)
Opportunities to unravel the electronic and structural properties of quantum materials and complex nanostructures on femtosecond time scales at the European XFEL
- Andreas Scherz (European XFEL)
18:20 - 18:40
18:40 END OF SESSION
END OF SESSION
18:40 - 18:50
18:50
18:50 - 20:20
Contributions

18:50 Quantum Computing for Optimization Problems in Synchrotron Radiation Facilities - George Kourousias (Elettra Sincrotrone Trieste)

18:50 The Training Catalogue for Photon and Neutron Data Services - Oliver Knodel (Helmholtz-Zentrum Dresden-Rossendorf)

18:50 Time resolved optical and Raman spectroscopy under ultra-high vacuum conditions: a novel apparatus for pump-probe multi-messenger investigations - Pietro Carrara (Università degli Studi di Milano - CNR IOM)

18:50 LOREA: the ARPES beamline at ALBA for quantum materials - Massimo Tallarida (ALBA-CELLS)

18:50 The SXP instrument at the European XFEL, a novel tool to investigate quantum materials - Manuel Izquierdo (European XFEL)

18:50 Inertial spin dynamics in epitaxial cobalt films - Vivek Unikandanunni (Stockholm University)

18:50 SAM-APDs based on quantum-engineered semiconductors for X-ray detection - Giorgio Biasiol (Consiglio Nazionale delle Ricerche, Istituto Officina dei Materiali)

18:50 Sensing quantum materials with X-ray nano diffraction: Beamline ID01 of the new Extremely Brilliant Source of the ESRF - Tobias Schulli (ESRF)

18:50 Nano focused synchrotron radiation for the thorough characterization of avalanche photodiodes and quantum well detectors with engineered band gap based on III-V semiconductors - Gianoncelli Alessandra (Elettra Sincrotrone Trieste)

18:50 The NFFA-APE integrated platform for growth and all-resolved synchrotron radiation spectroscopy studies on quantum materials - Ivana Vobornik (CNR-IOM)

18:50 Imaging band structure of novel quantum materials by ARPES - Lukasz Plucinski

18:50 The pump-probe laser infrastructure of the SXP instrument at the European XFEL - Patrik Grychtol (European XFEL)

18:50 The NFFA-SPRINT user facility for ultrafast photoelectron spectroscopy in the 17-31 eV photon energy range based on a coherent narrowband light source up to 200KHz repetition rate* - Pietro Carrara (CNR-IOM)

18:50 The spatio-temporal coherence and x-ray wavefront investigation at the European XFEL - Mikako Makita (European XFEL)

18:50 Mammalian rhodopsin dynamics using an X-ray free electron laser. - Gebhard F.X. Schertler (Paul Scherrer Institut, Villigen, Switzerland)

18:50 Instrumentation for experiments in quantum materials at ALBA XMCD&XRMS beamline BOREAS, present status and vision - Manuel Valvidares (ALBA Synchrotron Light Source)

18:50 Magnetic field optimization for HTS Staggered Array Undulator samples - Xiaoyang Liang (Paul Scherrer Institut)

18:50 Emergent quantum states visualized by the cutting-edge ARPES instruments at BESSY II - Rui Lou (IFW Dresden and HZB)
Wednesday 18 May 2022
09:00 Quantum technology and the Quantum Flagship - Tommaso Calarco (Forschungszentrum Jülich)
Quantum technology and the Quantum Flagship
- Tommaso Calarco (Forschungszentrum Jülich)
09:00 - 10:00
TUTORIAL
10:00 ARPES microscopy and the effect of electric gating - Alexei Barinov (Sincrotrone Trieste)
ARPES microscopy and the effect of electric gating
- Alexei Barinov (Sincrotrone Trieste)
10:00 - 10:30
10:30 Coffee break
Coffee break
10:30 - 11:00
11:00 Bragg Projection Ptychography and Correlated Tomography of III-V Nanowire Heterostructures - Megan Hill (University of Cambridge)
Bragg Projection Ptychography and Correlated Tomography of III-V Nanowire Heterostructures
- Megan Hill (University of Cambridge)
11:00 - 11:30
11:30 Materials Science of superconductor nanowires - Kristiaan Temst (KU Leuven, Quantum Solid State Physics)
Materials Science of superconductor nanowires
- Kristiaan Temst (KU Leuven, Quantum Solid State Physics)
11:30 - 12:00
12:00 k-resolved electronic structure of quantum heterostructure and impurity systems by soft X-Ray ARPES - Vladimir N. Strocov (Swiss Light Source, Paul Scherrer Institute)
k-resolved electronic structure of quantum heterostructure and impurity systems by soft X-Ray ARPES
- Vladimir N. Strocov (Swiss Light Source, Paul Scherrer Institute)
12:00 - 12:30
Soft-X-ray angle-resolved photoelectron spectroscopy (ARPES) in the photon-energy range around 1 keV combines resolution in electron momentum **k** with enhanced photoelectron escape depth. These benefits allow previously unthinkable **k**-resolved electronic structure studies on buried heterostructures and impurities, which are in the heart of solid-state quantum devices. For example, soft-X-ray ARPES experiments on AlGaN/GaN high-electron-mobility transistor heterostructures find anisotropy of the interfacial quantum-well states, resulting in anisotropic high-field electron transport [Nature Comm. **9** (2018) 2653]. For the oxide interfaces LaAlO3/SrTiO3, resonant photoexcitation of the Ti-derived interfacial charge carriers resolves their multiphonon polaronic nature, fundamentally limiting their mobility [Nature Comm. **7** (2016) 10386]. Experiments on NbN/GaN superconductor/semiconductor heterostructures find that the Fermi states of NbN are well separated from the GaN states in energy and **k**. Excluding poisoning of the superconductivity, this allows the integration of NbN-based quantum devices into semiconductor technology [Sci. Adv. **7** (2021) eabi5833]. Impurity systems are illustrated by In(Fe)As, where resonant photoexcitation of the Fe-derived states identifies their full integration into the conduction band of GaAs, allowing high mobility of spin-polarized electrons [Phys. Rev. B **103** (2021) 115111]. Other cases include magnetic V impurities in the topological Bi3Se2 competing with the quantum anomalous-Hall effect, etc.
12:30 LUNCH BREAK
LUNCH BREAK
12:30 - 14:30

14:30

14:30 - 15:30
15:30 Scattering probes for quantum electronics and strain engineering for quantum devices - Paul Evans (University of Wisconsin-Madison)
Scattering probes for quantum electronics and strain engineering for quantum devices
- Paul Evans (University of Wisconsin-Madison)
15:30 - 16:00
Quantum electronic devices in epitaxial semiconductor heterostructures are based on an extremely precise level of control of the control of structure and compositions. Epitaxial growth techniques provide substrates with exceptionally low concentrations of chemical impurities and structural defects such as dislocations and stacking faults. The advent of quantum devices establishes a new range of structural problems associated with the comparatively large size of quantum devices and the small splitting of quantum states. Structural features of interest include atomic steps at heterostructure interfaces, complex stress distributions arising from the formation of electrodes, and the thermal stress arising during cooling to low temperatures. This talk surveys the electronic evidence for structural effects and illustrates the scale of distortion relevant to quantum devices. Prospects for exploiting these structural features to provide new routes for device fabrication will be presented. Other structural effects will impact the integration of other quantum devices and will be briefly discussed.
16:00 Understanding quantum materials by time-resolved x-ray methods - Simon Gerber (Paul Scherrer Institut)
Understanding quantum materials by time-resolved x-ray methods
- Simon Gerber (Paul Scherrer Institut)
16:00 - 16:30
16:30 Study of heterostructures based on nanowires using the synchrotron beam nanoprobe - Tobias Schulli (ESRF)
Study of heterostructures based on nanowires using the synchrotron beam nanoprobe
- Tobias Schulli (ESRF)
16:30 - 16:50
16:50 Coffee break
Coffee break
16:50 - 17:20
17:20 Functionality from disorder - Christian Schuessler-Langeheine (Helmholtz-Zentrum Berlin)
Functionality from disorder
- Christian Schuessler-Langeheine (Helmholtz-Zentrum Berlin)
17:20 - 17:40
In materials with inhomogeneity, macroscopic properties depend not only on local electronic or magnetic properties but also on the way inhomogeneity is spatially distributed. Controlling this spatial pattern may therefore create new functionality. Modern X-ray sources provide the means for mapping out the spatial distribution of, e.g., magnetic domains or coexisting phases as well as for tracking the evolution of spatial patterns in time. Such experiments enable us to develop strategies for controlling disorder. I will show examples for coexisting phases and complex magnetic patterns and will discuss relevant length and time scales for future experiments.
17:40 Understanding how strain engineering shapes spin-orbital interactions and charge gap in Sr2IrO4 by Resonant Inelastic X-Ray Scattering - Thorsten Schmitt (Paul Scherrer Institut)
Understanding how strain engineering shapes spin-orbital interactions and charge gap in Sr2IrO4 by Resonant Inelastic X-Ray Scattering
- Thorsten Schmitt (Paul Scherrer Institut)
17:40 - 18:00
Understanding the relationship between entangled degrees of freedom (DOF) is a central problem in correlated quantum materials and the possibility to influence their balance is promising toward realizing novel functionalities. In the single-layer iridate Sr2IrO4, the interaction between spin–orbit coupling and electron correlations induces an exotic ground state with magnetotransport properties promising for antiferromagnetic spintronics applications. Moreover, the coupling between orbital and spin DOF renders the magnetic structure sensitive to the Ir–O bond environment. We use strain engineering to perturb the local lattice environment and, by tracking the response of the low-energy elementary excitations by Resonant Inelastic X-Ray Scattering (RIXS), we unveil the response of the microscopic spin and charge interactions. By applying tensile strain, we observe a large softening of the spin(-orbital) wave dispersion along the [h,0] direction and a simultaneous hardening along the [h,h] direction. This evolution entails a strain-driven crossover from anisotropic to isotropic interactions between the magnetic moments. We also show how the charge excitations are coupled to the lattice in Sr2IrO4. We unveil the evolution of a dispersive electron-hole pair excitonic mode which shifts to lower (higher) energies upon compressive (tensile) strain, manifesting a reduction (increase) in the size of the charge gap.[1] [1]: https://www.pnas.org/content/117/40/24764
18:00 Ferrimagnetic switching driven by stochastic resonance in multiferroic (Ge,Mn)Te - Juraj Krempasky
Ferrimagnetic switching driven by stochastic resonance in multiferroic (Ge,Mn)Te
- Juraj Krempasky
18:00 - 18:20
The interplay between spin-orbit interaction (SOI) and magnetic order is currently one of the most active research fields in condensed matter physics. We report on ferrimagnetic switching driven by stochastic resonance in multiferroic (Ge,Mn)Te, investigated by x ray magnetic linear and circular dichroism (XMLD/XMCD), supported by SPR-KKR-CPA scattering and magnetic cluster calculations. In accordance with our previous resonant ARPES results, we find that the Mn-atoms occupy two distinct substitutional and interstitial lattice sites by substituting Ge-atoms. We show that (Ge,Mn)Te antiferromagnetically couples its Mn-sites with slightly different magnetic moments, resulting in a ferrimagnetic order. One of the astonishing results is that XMCD data show that the system spontaneously switches its magnetisation direction, without changing external parameters such as light helicity, applied B-fields or temperature (up to 65 K). The switching reveals ultra-slow magnetization dynamics, which can be governed by the stochastic resonance. Finally, we demonstrate that the occurrence of ferrimagnetic switching is closely related to the formation of topological spin textures in the films, enabled by the interplay of antiferromagnetic and Dzyaloshinskii-Moriya interactions.
18:20 END OF SESSION
END OF SESSION
18:20 - 20:00

20:00 SOCIAL DINNER
SOCIAL DINNER
20:00 - 22:00
Thursday 19 May 2022
09:00 Quantum cryptography - Antonio Acin
Quantum cryptography
- Antonio Acin
09:00 - 10:00
TUTORIAL
10:00 Imposing orbital angular momentum on soft x-rays - Ian McNulty (MAX IV)
Imposing orbital angular momentum on soft x-rays
- Ian McNulty (MAX IV)
10:00 - 10:30
10:30 Coffee break
Coffee break
10:30 - 11:00
11:00 Quantum imaging with FEL radiation - SHARON SHWARTZ
Quantum imaging with FEL radiation
- SHARON SHWARTZ
11:00 - 11:30
11:30 Quantum optics and nuclear physics - Adriana Palffy (Max Planck Institute for Nuclear Physics, Heidelberg, Germany)
Quantum optics and nuclear physics
- Adriana Palffy (Max Planck Institute for Nuclear Physics, Heidelberg, Germany)
11:30 - 12:00
12:00 Quantum state features of FEL radiation from the occupation number statistics - Giovanni Perosa (Università degli Studi diTrieste)
Quantum state features of FEL radiation from the occupation number statistics
- Giovanni Perosa (Università degli Studi diTrieste)
12:00 - 12:20
The statistical features of the radiation emitted by Free-Electron Lasers (FELs), either by Self-Amplified Spontaneous Emission (SASE-FELs) or by seeded emission (seeded-FELs), are attracting increasing attention because of the use of such light in probing high energy states of matter and their dynamics. We decided to shift the focus from correlation functions towards the reconstruction of the distribution of the occupation numbers of the radiation energy states. We propose a Maximum Likelihood reconstruction of the diagonal elements of the FEL radiation states based on the statistics of no-click events. The ultimate purpose of such a novel approach to FEL radiation statistics is the experimental confirmation of the departure from Poissonian statistics that SASE-FEL radiation exhibits and the laser-like coherence of seeded-FEL light. In this framework, it is interesting to note that the outcome of this work can be extended to any process of harmonic generation from a coherent light pulse, ushering in the study of the preservation or generation of quantum features in general non-linear optical processes.
12:20 LUNCH BREAK
LUNCH BREAK
12:20 - 15:30
15:30 Deep-learning assisted ptychography in the soft X-ray regime - Masoud Mehrjoo (Deutsches Elektronen-Synchrotron)
Deep-learning assisted ptychography in the soft X-ray regime
- Masoud Mehrjoo (Deutsches Elektronen-Synchrotron)
15:30 - 15:50
Quantum imaging methods, analogous to ptychography, have been recently proposed to assess the state of quantum systems. In ptychography, an overlapping illumination scans a sample and generates diffraction patterns that can be numerically converted to a high-resolution image of the sample. An ideal conversion demands precise knowledge of scan coordinates, low-noise measurements and illumination stability. In practice, the aforementioned criteria might not be completely achievable. Thus, the computational conversion inevitably fails to converge. We demonstrate an automatic differentiation based ptychography that optimises fluctuations leading to successful imaging for photon sources exhibiting shot-to-shot fluctuations, like X-ray free-electron lasers. Automatic differentiation is used in deep learning and optimisation as a set of techniques for evaluating derivatives. Various quantum imaging approaches can benefit from the proposed ptychography platform, like ghost imaging at soft X-ray free-electron lasers. We report on the results of our recent ptychography experiments at the FLASH2 facility at DESY.
15:50 Coffee break
Coffee break
15:50 - 16:20
16:20 Spectroscopic micro-imaging with off-axis zone plates - Jan Oliver Schunck (Deutsches Elektronen-Synchrotron DESY)
Spectroscopic micro-imaging with off-axis zone plates
- Jan Oliver Schunck (Deutsches Elektronen-Synchrotron DESY)
16:20 - 16:40
Soft X-ray spectroscopies usually average the observed response of a sample across the entire illuminated area. This restricts the obtainable information, especially if the sample is inhomogeneous (either because of electronic domain formation or patterning on the micro- and nanoscale). Formation of electronically distinct domains has been observed for various quantum materials. A complete understanding thus necessitates a domain-resolved experimental approach. We demonstrate the implementation of an experimental setup, build around an off-axis Fresnel zone plate, which enables imaging X-ray absorption spectroscopy and resonant inelastic X-ray scattering with a current spatial resolution down to 1.8µm. The zone plate, located between sample and detector, disperses X-rays scattered from the sample and also images the sample along the direction perpendicular to the dispersion. Incident X-rays are focused to a 1mm long line such that excitation spectra from each point along the line are measured in-parallel. In a microstructured VO2 thin-film, we find that the structure edges undergo the insulator-metal transition earlier than the centers, hinting at facilitated strain release. We believe that the observed effects apply in general to patterned films of quantum materials and provide a tool for adequate experimental studies. Reference: J.O. Schunck et al. Optica 8(2), 2021
16:40 CONCLUSION and results of the group discussion - Oliver Rader
CONCLUSION and results of the group discussion
- Oliver Rader
16:40 - 17:10
17:10 END OF SESSION
END OF SESSION
17:10 - 17:20
Friday 20 May 2022

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