scanning probe microscope with surface preparation for spectroscopy of quantum excitations

• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: Funded in 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 452252874

The ongoing miniaturization of electronic components has reached a limit where quantum physics and many body effects become increasingly important. Shrinking device dimensions brings exotic, electronic effects with it that are governed by strong fluctuations on femto- to picosecond time scales and on length scales of only a few nanometers. In general, most material properties are determined by the interaction strength of electrons with each other and with lattice vibrations. However, a microscopic description for most of these phenomena is lacking and new experimental probes with high spatial and temporal resolution are needed. In order to examine exactly these interactions on a microscopic level, a new scanning probe microscope system is proposed, one that can measure quantum excitations with atomic spatial and picosecond time resolution: quantum excitation microscope.To this end, a scanning force microscope and an optical scanning near field microscope with ultrafast electronic and optical pump-probe capabilities will be combined. With this novel instrument, time-dependent fluctuations of complementary physical variables can be spatially resolved (among them are charge distribution, magnetic ordering, dielectric polarization, as well as energy spectroscopy of electronic, photonic and magnetic excitations). The comprehensive characterization of these properties all on the same surface will allow access to phenomenon in solid state physics, that have not been within the experimental scope before.The quantum excitation microscope will the spatially resolved visualization of metal-insulator transitions and their characteristic fluctuations in correlated electron systems. In addition, the new instrument will allow selective manipulation of the dynamics of these phase transitions with defects and dopant atoms.A major goal is to build atomically structured materials and to resolve the ultra-fast dynamics of quantum excitations therein with high spatial resolution. The combination of ultra-fast scanning force microscopy with tip-enhanced Raman spectroscopy enables the assembly of atomically defined structures on surfaces that can be used as new quantum sensors. Prototypical sensor applications include the detection of nanoscopic magnetic and electric fields as well as small lattice distortions.Moreover, the unique combination of energy-resolved excitation spectroscopy and time-resolved pump-probe spectroscopy can demonstrate quantum mechanical entanglement of spin- or charge excitations on surfaces. The important questions of how entangled states propagate through extended atomic and molecular networks, and how decoherence could be suppressed in such systems are still unanswered and will be addressed in this work. To that end, functionalized surfaces on which spin- and charge states with long coherence times can exist will be developed, and atom manipulation will be used to create individual structures that can host entangled states.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Zeitauflösendes Rastersondenmikroskop mit Oberflächenpräparation
• Instrumentation Group: 5091 Rasterkraft-Mikroskope
• Applicant Institution: Universität Stuttgart
• Leader: Professor Dr. Sebastian Loth