Headed by professor Per Delsing.


The goal of the research is to understand, describe and utilize electron transport in very small metallic, superconducting and molecular systems.

 The measured samples are typically made with electron beam lithography and have minimum feature sizes down to 20nm. The research can be divided into two main tracks:

 i) Experiments for basic understanding of quantum mechanics in solid state structures.


ii) Sensors and detectors based on small solid state structures.

Under the first category we make experiments on qubits, the elementary building blocks for a quantum computer, trying to understand how Macroscopic Quantum Coherence can be used to do very powerful computations. Circuits including Josephson junctions can behave as artificial atoms and thus be used as qubits. We have developed tunable superconducting cavities, which can be used to couple these qubits.

Based on the qubits and the tunable cavities we are now developing new on-chip components for generating, detecting and rerouting single microwave photons. The cavities can also be used for parametric amplification.

 An important key component for the sensor research is the Single Electron Transistor (SET), which is the most sensitive electrometer known. A very fast and sensitive version of the SET, using rf-reflectometry is the so called RF-SET. In one of the sensor projects the RF-SET is used to measure very small currents by counting the individual electrons passing in a circuit (Counting). The SET can also be placed at the tip of a scanning probe instrument to form a "Scanning-SET" which can study sub electron charge distributions on surfaces. The very high charge sensitivity of the RF-SET can also be used to detect for example photons. In different projects we develop photon detectors where an incoming photon generates charge carriers, which are then detected by an RF-SET.

 We are also studying individual molecules by putting them between closely spaced metallic electrodes and forming a single-molecular transistor or switch. The scientific aim is to understand transmolecular conductance at a single molecule level and how it is affected by the strength of the electronic coupling to the electrode and to internal degrees of freedom such as vibrations, conformational changes, intramolecular electronic levels, spins, or external stimuli (e.g. magnetic field, light).

The work is to a large extent based on the device fabrication capabilities in the MC2 clean room (http://www.chalmers.se/mc2/EN/laboratories/nanofabrication). Key processes used in the device fabrication include: 

• Electron beam lithography for high resolution patterning
• Optical lithography for lower resolution patterning
• Reactive ion beam etching and reactive ion etching for anisotropic etching of metals, semiconductors and dielectrics
• Evaporation of metals

Key equipment in our low temperature laboratory:

• Three dilution refrigerators
• One He3 cryostat
• A multitude of measurement instruments for dc, rf and microwave
  

Contact:

Prof. Per Delsing

Dr. Sergey Kubatkin