Quantum Bits - QUBITS
Superconducting quantum bits can also be thought of as artificial atoms and the technology for engineering these atoms has matured substantially over the last decade. In Linneqs, we use this technology for investigating a number of diverse basic physical phenomena such as: properties of High-Tc Superconductors, the dynamical Casimir effect, quantum optics on chip and phonons at the single quantum level. The research aims more at using the properties of qubits than to build system with a large number of qubits.

Projects:

• “Qubits and quantum optics”, PI Per Delsing
• "Theory for Superconducting Qubits and Microwave Photonics", PI Göran Johansson
• “Connecting propagating phonons to qubits", PI Per Delsing
• "High-Tc Superconductor Qubits", PI Floriana Lombardi

 
Quantum Transport
New nanotechnologies allow us to study processes in quantum devices for qubit applications and ultra sensitive detectors. The future efforts within quantum transport build on the original LINNEQS agenda, studying non-equilibrium properties of superconductors, developing new superconducting devices and the investigation of single-molecule devices. In addition, there are new projects addressing the hot fields of strongly correlated oxide interfaces and topological insulators.

Projects:

• "Quantum Transport Theory", PI Vitaly Shumeiko
• "Atomic-scale electronics with layered superconductors: Intrinsic Josephson Junctions", PI August Yurgens
• “HTS nanorings and nanoSQUIDs”, PI Floriana Lombardi
• “Inhomogeneous unconventional superconductivity in hybrid superconducting-ferromagnetic devices”, PI Tomas Löfwander
• "Transport in Single-Molecular Devices", PI Sergey Kubatkin
• “Topological insulators”, PI Floriana Lombardi
• “Quantum transport in strongly correlated oxide interfaces”, PI Alexey Kalabukhov

Future Graphene Devices
The recently very successful work on graphene has shaped a new focus point of the centre, with three new projects including aspects of high-quality fabrication, novel devices and theoretical modeling. There is also a fair amount of cross-fertilization between the Graphene and Quantum Transport, with subprojects on e.g. graphene electrodes used for single-molecular devices and high-temperature superconductors as ultraflat support for graphene.

Projects:

• “Devices based on large area epitaxial graphene”, PI Sergey Kubatkin
• “CVD Graphene for Fundamental Physics and Applications”, PI August Yurgens
• " Quantum transport theory of graphene ", PI Tomas Löfwander

 
Enabling Technologies
We aim at developing:

1) a Near Field Scanning Microwave Microscope (NFSMM) with a sensitivity to capacitance variations up to 10-20 F (close to the capacitance of a single molecule). This will e.g. enable dispersive measurements on small molecular ensembles as well as the study of inhomogeneity in graphene, 

2) a new technology to isolate and study the tunnel barriers at the atomic level, using both imaging and spectroscopy This technology enables a far better understanding of imperfections and noise, and will thus improve our junctions.

3) Many of the projects we are running would benefit greatly from a better microwave amplifier than the HEMT amplifiers we are presently using. A parametric amplifier would improve the signal to noise by at least one order of magnitude.

 Projects:

•  "Scanning SET microscope", PI Sergey Kubatkin
• "High resolution imaging and spectroscopy", PI Eva Olsson
• “A parametric microwave amplifier”, PI Per Delsing