4K measurement station
To rapidly test and iterate device and material design parameters we have a Lakeshore Cryotronics probe station that has been modified, in-house, to be compatible with the board loading system used in our dilution refrigerators.
Samples are cooled to 4K by a cryo-free pulse tube in approximately 3 hours and material parameters such as field effect mobility can be tested in conditions that are close to the milli-Kelvin temperatures that are needed for our final device operation. If required these devices can then be directly loaded to a dilution refrigerator to access sub-Kelvin temperatures and to apply large magnetic fields.
Specially designed modular PCB sample holders
Fast operation of the quantum devices requires usage of specially designed sample holders that guarantee small cross-talk between wide-bandwidth lines, low parasitic capacitances and possibility of placing small electrical components in the nearest vicinity of the sample. In our lab we use modular PCB sample holders designed in a QDev-spin-off company QDevil. They use a set of components that work reliably in sub-kelvin temperatures and that survive repeated thermal cycling, and their layout is optimized to minimize pain of bonding the devices with tens on electrodes.
Specially designed PCBs
Cryo-free dilution refigerators
The study of quantum devices at QDev is performed at sub-kelvin temperatures, for which purpose the center has 12 cryo-free dilution refrigerators, all with base temperature below 20 mK. The refrigerators are equipped with a bottom loading system, which enables to thermocycle samples between base and room temperature within 16 hours, providing efficient feedback in a cycle of design, fabrication and characterization of the quantum devices. Internally, each fridge is optimized for different kind of experiments. Some of the customizations are:
- a superconducting vector magnet that can generate magnetic field up to 6 T vs. aluminum shielding for low magnetic noise operation of superconducting qubits
- up to 42 high frequency coaxial lines for sub nanosecond voltage manipulation of the devices vs. heavy-filtered DC-only setup for low-temperature and low-noise material study
- low-noise conventional and parametric cryogenic amplifiers for optimal RF reflectometry and transmition measurements
Wide range of low- and high-frequency electronics
Study of the novel devices requires a wide arsenal of manipulation techniques that explore bandwidth extending from DC to tens of gigahertz. The arsenal of equipment avaliable at QDev starts from conventional DC low-noise voltage and current sources and amplifiers, extends through microwave electronics that can be composed into custom RF circuits and ends at nanosecond-resolution arbitrary waveform generators and acquisition cards as well as super-gigagertz vector signal generators.
Custom built microwave device
AJA sputtering & Evaporation
AJA 10kV electron beam evaporators allow depositing a variety of materials [Al, Au, Ge, Pt, Cr, Pd, V, Ti, SiOx, Cr]. It is also possible to sputter materials which do not evaporate well such as W or NbTiN. The evaporators also allow insitu Kaufman and RF milling.