High-performance semiconductor heterostructure development for hybrid quantum devices

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The student projects will focus on devices based on in-house synthesized semiconductor heterostructures. The semiconductor heterostructures are the material platform for large-scale topological quantum computation. Their performance plays a critical role in determining the performance of the whole computing chip. Currently, we are characterizing the performance of the heterostructures in gated hall bar devices. Based on this, we can extract mobility, electron density, weak anti-localization effects and other quantum properties of heterostructures, so we can give feedback and then improve the performance  of the materials.

The projects require close interactions with researchers who are growing the semiconductor heterostructures. The projects will involve structure characterization, nanoscale device fabrication, electrical transport measurements and advanced data acquisition/analysis. The master candidate will have a good chance to have hands-on state-of-the-art instrumentation throughout the project.

If you are interested, do not hesitate to contact Yu Liu (yu.liu@nbi.ku.dk) or Peter Krogstrup (krogstrup@nbi.ku.dk)

Majorana zero modes in SAG nanowires

The physics of Majorana modes have been the subject of intense experimental research at the Center for Quantum Devices. Majorana modes exist in the topological phase of one-dimensional semiconductor-superconductor nanostructures and hold the promise to enable quantum computing. Thus, they are a hot research topic in solid-state physics with strong relevance for future computer hardware.

The material we work on are semiconducting InAs nanowires proximitized by superconducting Al. This combines a conventional superconductor and a semiconductor with strong spin-orbit interaction. In our particular approach, we use nanowires produced by selective area growth (SAG). This allows for two-dimensional nanowire networks that can be used to build novel devices. Read more here >>

 If you are interested in being involved please contact Charlie Marcus (marcus@nbi.ku.dk).

Building an advanced 3D platform for controlled growth of hybrid nanowires

In Microsoft Quantum Material Lab, we are working on developing quantum information processing hardware. Hybrid semiconductor-superconductor nanowires crystals hold the potential as building blocks of future quantum computers. Therefore, towards the optimization of these materials, combined efforts in the fields of quantum physics and advanced material engineering is necessary for the success of the project. Read more here >>
If you are interested in being involved please contact Peter Krogstrup (pekrogst@microsoft.com).
Experiments on quantum wires and hybrid quantum dots 

Student projects will focus on devices based on nanostructured materials synthesized in-house such as semiconductor nanowires or carbon-based materials. When superconducting electrodes are attached to such wires, they form quantum dots where we can study the states arising in such ”artificial superconducting atoms/molecules”. Currently we are investigating these quantum states and the coupling between them in different multi-quantum-dot geometries consisting of, e.g., serial or parallel double quantum dots contacted with one or more superconducting electrodes. Read more here >>

If you are interested in being involved please contact Kasper Grove-Rasmussen (k_grove@fys.ku.dk) or Jesper Nygård (nygard@nbi.dk).

Topological Superconductivity in 2D Electron Gases 
Topological superconductors are a new class of materials, expected to hold a superconductive gap in their bulk and protected states at their boundaries. These states are called Majorana modes, and are attracting an enormous experimental and theoretical interest. Our research objective is to take topological superconductors to the new dimension by developing a 2D platform for creating, studying and manipulation Majorana modes. We are looking for motivated bachelor and master students to side us in our research. During your stay you will be involved in nano fabrication of devices, electrical measurements at cryogenic temperatures, data analysis and much more. Our interest ranges from studying fundamental properties of matter to using Majorana modes for quantum computation. Read more here >>

If you are interested in being involved please contact Charlie Marcus (marcus@nbi.dk).

Electron Spin Based Qubits 

Our spin qubit team is looking for bachelor and master students to work on several new projects to fabricate, control, read out, and couple single electron spins to make quantum mechanical bits, the building block for a quantum computer. Using state-of-the-art electron beam lithography at the center’s nanofabrication facilities we are able to fabricate semiconducting quantum dots of ~ 100 nm in size. These dots contain a single electron, like an artificial hydrogen atom. We work on the material platforms SiGe, silicon-on-insulator and GaAs. At sufficiently low temperatures (tens of millikelvin) we can couple these quantum dots to each other. By applying high frequency pulses (MHz to GHz regime) we can control and read out their spin state with high fidelity.

GaAs Spin Qubits project, read more here >> 
Silicon Spin Qubits project, read more here >>

If you are interested in these or other projects of the spin qubit team, please contact  Ferdinand Kuemmeth (kuemmeth@nbi.dk).

Nanostructured materials such as semiconductor nanowires are produced and analyzed at HCØ. These materials are fascinating in their own right and are also employed in a variety of devices ranging from sensors to quantum electronics. At QDev we focus mainly on their applications as quantum wires and dots. This research bridges advanced materials science and quantum physics. Students with an interest in growth, structural properties, nanoscale imaging (electron microscopy) or the physics of nanowires can get introduced to the various nanowire research groups and learn more about potential projects and supervisors. Knowledge of basic solid state physics is strongly recommended, e.g. from introductory courses on condensed matter physics.Read more here >>

If you are interested in being involved please contact Jesper Nygård (nygard@nbi.dk) or Peter Krogstrup (krogstrup@nbi.dk).

Semiconductor Nanowire-Based Superconducting Qubits 
Superconducting qubits are a leading platform for building a quantum computer.  Our group has recently developed a new type of superconducting qubit based around a semiconductor nanowire element that enables simplified control. Bachelor’s and Master’s projects are available exploring experimentally how these qubits can be scaled to multi-qubit processors that allow us to execute primitive quantum algorithms with high precision. Projects will focus on different aspects of this goal, from fabrication of multi-qubit devices to high fidelity qubit control and readout, working as a part of a team of researchers and collaborating closely with theorists and computer scientists. Experiments will utilise state-of-the-art nanofabrication and low temperature measurement facilities at the Center for Quantum Devices.  Read more here >>

If you are interested in being involved please contact Karl Petersson (karl.petersson@nbi.ku.dk) or Charlie Marcus (marcus@nbi.dk).

Mesoscopic electronic devices at the interfaces of complex oxides 

We have available master projects in the sub-group working on the physics of complex oxides heterostructures. This system has remarkable properties: In some aspects it behaves as a semiconductor with properties that can be tuned by electrical fields. However, in contrast to semiconductors, the electrical field not only changes the conductivity, but can also drive quantum phase transitions into superconducting or magnetic regimes. These properties belong to the realm of correlated materials and are completely unheard of in conventional semiconductors. Read more here >>

If you are interested in getting involved in the research projects contact Thomas Sand Jespersen (tsand@fys.ku.dk).