## Nanophysics

Nanophysics and all nanoscale sciences have been strongly on the rise for over twenty years and promise many more groundbreaking developments.

The nanoworld is a land of dwarves: we are fascinated by the smallest functional structures making up matter, whose size is on the order of a nanometer - a billionth of a meter. The laws of the nanoworld are different from those governing our everyday experience. Quantum effects are important in most materials and give rise to different properties than we are familiar with on a macroscopic scale.

Nanophysics forms the basis of many phenomena in medicine, life sciences and chemistry, and represents an important interface to these sciences.

We experimentally explore the electronic and optical properties and the surfaces of a variety of interesting and novel materials. This research is based on the development and continuous refinement of nanoscale imaging techniques whose resolution is reaching the atomic scale. Our know-how feeds into new materials and diverse areas of technology: nanoscale sensing devices, tools for medical diagnostics, energy efficiency and storage and solar technology.

## Quantum Technology

**Randomness and uncertainty as the basis for a technological revolution.**

The phenomena of quantum physics can be observed with electrons, atoms or photons and in condensed-matter systems such as metals or semiconductors, which play an important role in our everyday life. In the quantum world, we observe many fascinating and at first sight unusual phenomena - such as quantum particles that can be in a superposition of different locations at the same time, or quantum jumps whose exact point in time is fundamentally random. As puzzling as these phenomena may seem, we are already seeing signs that they will form the basis for a revolution of modern technology. There is almost no other field of science where pure basic research and technological applications of revolutionary impact are so seamlessly intertwined.

A hot topic is the fast growing field of quantum computing and quantum technology. This field unites quantum physics with information technology, to develop, among other things, ultra-fast supercomputers and new measuring instruments that will revolutionize many areas of science, communication and the internet. Researchers in our Department explore many important fields of quantum physics, such as the solid-state physics of metals, superconductors, semiconductors, magnets, graphene, quantum Hall and topological systems, low temperature physics, scanning probe physics, nano and quantum optics, as well as the quantum physics of ultracold atomic gases.

# Prof. A. Hofmann's Group

Our group performs transport measurements of semiconductor devices at cryogenic temperatures to study a variety of physical phenomena such as: the spin-orbit interaction (SOI), heavy-hole light-hole mixing, proximization of semiconductors with superconductors, quantum hall effect, thermodynamics.

# Prof. P. Maletinsky's group

Our research is directed towards the development and application of sensors based on individual, well-controlled quantum systems ("quantum sensing"). The workhorse for our experiments is the Nitrogen-Vacancy centre in diamond, whose exceptional spin and optical properties render it an ideal candidate for various nanoscale sensing tasks. A major topic we are interested in is nanoscale magnetic and optical imaging for various applications in solid-state and mesoscopic physics. Furthermore, we investigate nanomechanical oscillators, whose motional degrees of freedom can be efficiently sensed (and potentially even entangled) with single spins.

# Prof. E. Meyer's group

The aim is to investigate physics of surfaces on the nanometer-scale. Ultra-sensitive force sensors are being developed. Phenomena, such as true atomic resolution of dynamic force microscopy, friction on the atomic scale, Kelvin force microscopy and mechanical detection of magnetic resonance are studied. One of the ultimate goals is the detection of single spins.

# Prof. M. Poggio's group

We are interested in using ultra-sensitive micro- and nano-mechanical resonators to probe quantum states. We study the quantum behavior of small mechanical structures, their coupling to single electron states, to spin states, to light, and to the larger environment around them. Sensors able to detect the tiny forces arising from single charges or spins allow the study of a wide class of problems in condensed matter physics. Improved understanding of these phenomena may lead to new high resolution nano- and atomic-scale imaging techniques.

# Prof. C. Schönenberger's group

Our research is directed towards static and dynamic electric-transport properties of nanostructures of various kind including normal metals, superconductors, and organic conductors. The structures are fabricated either by high-resolution electron-beam lithography or by using a chemical approach.

# Prof. P. Treutlein's group

Our research focuses on the quantum physics of ultracold atoms and on their interactions with solid-state micro- and nanostructures. The main experimental tool is an atom chip, which allows us to laser cool, trap, and coherently manipulate ultracold atoms at micrometer distance from a chip surface. We use tailored potentials generated by microstructures on the chip to perform quantum atom optics experiments with Bose-Einstein condensates (BECs).

# Prof. R. Warburton's group

The Nano-optics lab is investigating charge and spins physics in optically active quantum dots, ultra-microscopy and bio-imaging, semiconductor physics, optics of semiconductor heterostructures and nanostructures.

# Prof. I. Zardo's group

The Nanophononics lab is investigating lattice dynamics and phonon transport in nanostructures, which allow to engineer phonons to a larger extent compared to bulk materials. In particular, the manipulation of phonons as coherent waves in solids is expected to allow fine control of heat conduction, which is of fundamental scientific interest and has promising technological impact. Furthermore, we study the interaction between phonons and charge carriers, spins, and photons, which is known to be pivotal in electronic, optoelectronic, quantum, sonic, and thermal devices.

# Prof. D. Zumbühl's group

Research focuses on mesoscopic and nanoscale physics, quantum coherence, spin and electron interactions in semiconductor nanostructures such as laterally gated quantum dots in GaAs 2D electron gases as well as graphene. We are pursuing coherent manipulation of quantum mechanical degrees of freedom in solid state nanostructures with the ultimate goal of implementing quantum computation schemes, for example in coupled electron spin qubits.

# Prof. C. Bruder's group

We use the methods of modern condensed-matter theory to investigate nanostructures (like semiconducting quantum dots or metallic resp. superconducting structures). These systems show fascinating quantum effects like quantum coherence or superconductivity.

# Prof. J. Klinovaja's group

Our group works on many aspects of the quantum theory of condensed matter systems with a special focus on topological effects and spin phenomena. We explore the physics of topological insulators, carbon-based systems (graphene, bilayer graphene, and carbon nanotubes), atomic chains, semiconducting 2DEGs, and nanowires. In our work, we not only study the properties of existing structures but also combine well-known ingredients to "engineer" systems with exotic quantum properties, in particular in the presence of strong electron-electron interactions treated by quantum field theoretical methods.

# Prof. D. Loss's group

Theoretical studies and basic research in condensed matter physics. Investigation of interacting quantum systems with special focus on finite-size effects and phase-coherence phenomena ("Aharonov-Bohm physics" in mesoscopic systems). Theory of superconductivity. Coulomb-blockade effects in quantum dots. Quantum computing and quantum communication. These topics are closely related to applications such as mesoscopic devices or magnetic storage in computers.

# Prof. P. Potts's group

The theory of thermodynamics was a driving force in the industrial revolution. By enabling the development of devices such as steam engines and refrigerators, it had a tremendous impact. At the nanoscale, where systems experience fluctuations and quantum effects, our thermodynamic understanding is still being expanded. Our group is a part of this exciting development which promises to produce important contributions to emerging nano- and quantum-technologies.