Periodic Reporting for period 3 - SiMS (Simulated Majorana states)
Período documentado: 2021-03-01 hasta 2022-08-31
Topological protection provides a route to protect fragile quantum states, which are otherwise very sensitive to noise and thermal fluctuations of the environment that surrounds them. In 2010, it was theoretically proposed that such topological protection could be achieved in hybrid nanoscale devices consisting of superconductor and semiconductor layers. The resulting quantum states, owing to the similarities with the theory of Ettore Majorana from the 1930’s, are called Majorana modes. The experimental search for the Majorana modes has been fueled by the possibility to reach hardware quantum error correction, vital for scalable quantum computation and would eliminate the huge number of physical quantum bits required for an error corrected logical quantum bit needed in the case of other types of quantum hardware.
The goal of the project is to investigate a novel direction in the creation of Majorana states, which is based on a linear array of quantum dots with superconducting leads. The key advantage of this physical implementation is the control of the device parameters, which will allow us to reproducibly map the topological phase diagram of the system. In order to achieve this overarching goal, we will utilize low frequency as well as microwave domain measurement techniques and will build our devices using narrow gap III-V semiconductors together with conventional metallic superconductors. Furthermore, we will investigate the non-locality of the Majorana bound states, and in doing so, we will demonstrate superconducting molecular states spanning between neighboring quantum dots.
The goal of the project is to investigate a novel direction in the creation of Majorana states, which is based on a linear array of quantum dots with superconducting leads. The key advantage of this physical implementation is the control of the device parameters, which will allow us to reproducibly map the topological phase diagram of the system. In order to achieve this overarching goal, we will utilize low frequency as well as microwave domain measurement techniques and will build our devices using narrow gap III-V semiconductors together with conventional metallic superconductors. Furthermore, we will investigate the non-locality of the Majorana bound states, and in doing so, we will demonstrate superconducting molecular states spanning between neighboring quantum dots.
Throughout the first part of the project, we have demonstrated the first model system, a double quantum dot device with superconducting leads. We have showed that the charge- and spin-state control and readout by means of the supercurrent that flows through the device. This successful experiment opened the way for the longer quantum dot chains, which will form the nanodevice required to fulfill the final goals of the project.
In addition, we have also demonstrated that an on-chip refrigeration method can cool down nanoscale electronic devices to unprecedentedly low temperatures in the microkelvin regime. This achievement will be useful to reduce thermal fluctuations in upcoming measurements, and may facilitate more precise tuning of the underlying quantum states or allow for longer operation times.
In addition, we have also demonstrated that an on-chip refrigeration method can cool down nanoscale electronic devices to unprecedentedly low temperatures in the microkelvin regime. This achievement will be useful to reduce thermal fluctuations in upcoming measurements, and may facilitate more precise tuning of the underlying quantum states or allow for longer operation times.
Thus far, we have achieved published scientific breakthroughs in nanoscale electronic refrigeration and in the direct interaction between supercurrent and single electrons hosted by quantum dot devices. These results are enabling technologies to improve quantum information processing techniques with spins or superconductivity in solid state devices.
The project team will now focus on the demonstration of the quantum non-locality and the measurement and mapping of the Majorana bound states with the final goal being the observation of their non-Abelian exchange statistics.
The project team will now focus on the demonstration of the quantum non-locality and the measurement and mapping of the Majorana bound states with the final goal being the observation of their non-Abelian exchange statistics.