Wang Lab of Quantum Matter

The ultra low-noise lab, of which we have one, is for the ultralow vibration and ultralow temperature STM experiments to be carried out in the basement of the Centre for NSQI. The keel slab that dominates the rooms, will isolate the cryostat from the vibrations coming out from the building and significantly improve the vibrational performance of the lab. Conduits pass between the rooms allowing control cables to run from the lab to the service room so that the experiment can be run in complete isolation. Features of the lab are listed below:

Low vibration:

• Deep foundations – the basement level sits directly on the building foundations. Two metres of concrete between you and the bedrock. The building is extremely stiff allowing any vibration to pass through with as little dissipation as possible (the energy does not stay in the building). The close match in material properties between the concrete and the bedrock then means that there is little reflection of the energy back into the building.
• Keel slab – a 23 tonne concrete slab surrounded by a floating floor. The keel slab is T-shaped in cross section, designed to keep the centre of gravity low and reduce any wobble in the block. The slab is then supported on pneumatic jacks, which are active, rather than passive dampers and are subsequently quieter than the damper pads (with a vibration window below 2 Hz). It is actually more vibrationally stable working on the keel slab floor than on the air tables that sit on the keel slab.
• Newport ST-UT series air tables.
• Sound-proof doors.
• Anti-vibration fittings – all services are mounted on springs or rubber mounts. Any pipework that enters the lab goes through a flexible section before breaching the wall.
• Controlled services – services (Air con, water, air extract) can all be shut off outside the lab to further reduce any noise.

Cartoon of the ultra-low noise lab keel slab

Low electrical noise:

• Faraday cages – the basement and individual labs are all faraday cages, with metal foil built into the walls and ceiling. For extra protection the foil edges are available to continue the cage across the window and door.
• DC task lighting – to avoid 50 Hz noise in photodetectors, the labs are fitted with separate DC lighting over the experimental area.
• Plastic service pipework – all pipework that enters the labs is plastic to avoid any antenna effects.
• Fibre-optic network – the data network runs over a fibre-optic system rather than Cat5e cables, to avoid introducing EM noise.
• Clean power – the labs are equipped with a clean power supply that is filtered by a 1:1 transformer outside each lab. There is also a dedicated earth for the basement.

Controlled environment:

• Total isolation – the possibility to run you experiment from another, sound proofed and isolated room.
• Liquid helium-ready – the ultra-low noise labs are fitted with dewar lifts, to drop helium dewars down to an appropriate level, and helium return pipes for the recovery of helium gas.
• Air conditioning – an individual re-circulating air conditioner in every lab.
• Services – air extract, water, and process chilled water in each lab, with shut offs for each outside the lab.