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Triton XL

Oxford Instruments

Triton XL specifically designed for quantum computing

The Triton XL range of dilution refrigerators enables higher cooling power, more sample space and achieves colder base temperatures than any other Cryofree dilution refrigerator on the market (3.3 mK has been demonstrated). Triton XL comes with two different dilution units based on the choice of base temperatures and cooling power:

• TritonXL 1000 with a guaranteed base temperature of < 5 mK (< 4 mK expected) and cooling power of 1000 µW at 100 mK
• TritonXL 400 with a guaranteed base temperature of <7 mK (< 6 mK expected) and cooling power of 400 µW at 100 mK

Typical performance of TritonXL 1000:

• Less than 4 mK base temperature
• 5 µW of cooling power at 10 mK
• 25 µW of cooling power at 20 mK
• Up to 1000 µW of cooling power at 100 mK (depending on the choice of pulse-tube cooler)
• 430 mm diameter mixing chamber sample plate
• Accepts up to two 1.5 W pulse tube refrigerators
• 100 mm central line of sight port for semi-rigid coaxes or a top loading exchange mechanism
• Six 50 mm line of sight ports for semi-rigid coaxes
• Five 50 mm non-line of sight ports for flexible wiring
• Integrates magnets up to 18 T or 200 kg
• A total of up to 70 semi-rigid coaxes with SMA connectors can be installed
  • Specifications
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  • Non-line of sight services
  • Line of sight services
  • PFDs
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• Base temprature:  < 7 mK for TritonXL 400 and < 5 mK for TritonXL 1000
• Cooling power at 20 mK: 8 µW for TritonXL 400 and 25 µW for TritonXL 1000
• Cooling power at 100 mK: 400 µW for TritonXL 400 and 900 µW for TritonXL 1000
• Cool down time: < 48 h
• Sample environment: vacuum
• Sample space: 430 mm diameter x 400 mm
• Top and bottom sample loading options
• Selected magnet options: up to 18 T

Temperature Stability

Temperature control is critical for careful sample characterisation of any new material or device. The inherent base temperature stability of the system without an active temperature control feedback loop can be seen in this graph. The temperature measured was 8.3 ± 0.2 mK. In separate experiments, when over biasing the control sensor, the closed loop control of the system can be improved.
In the temperature range 20 – 300 mK, control better than 10 μK has been achieved. Also shown here is the measured mixing chamber temperature, whilst controlling the temperature at 30 K and simultaneously ramping an integrated magnet from zero field to 12 T and back to zero at 0.3 T/min. The standard deviation of the temperature measurements was 3.5 mK and the maximum deviations were approximately ± 7 mK.

Demountable Impedance

Despite highly efficient cold traps, small amounts of contamination may accumulate after a few years of operation. The Triton design with easily accessible and demountable impedance on a standard VCR gasket fitting, makes it easy to change this component, should it be necessary.

Cold Traps

Internal charcoal traps operating at 60 K, is capable of adsorbing more than 1 L of air contamination.
The system can easily operate for more than 6 months without having to warm it up.
Long hold time of the LN2 dewar for the external cold trap, requiring only one top-up per week. Dewar with even longer hold time is available on request.


Professionally soldered sensors (4-wire read out) are installed on all five experimental plates with demountable connectors for ease of service. Sensors and heaters are operated using a Lakeshore 370AC bridge with a 16 channel scanner.
The mixing chamber RO2 sensor is cross-calibrated in the factory against a primary Co60 nuclear orientation (NO) crystal. Because resistance thermometry is sensitive to changing RF environment, we offer the calibration to be repeated during installation to confirm its accuracy.

Integrated Gas Handling System

The welded assembly with high performance, pneumatically controlled, bellow-sealed valves offer minimum risk of through leaks. Integrated pressure-relief valves protect against pressure build-up due to a power cut or cryogenic blockage. Switches allow for manual control of all pneumatic valves, without having to rely on the software (requires 5 bar compressed air supply).

Oil and Dust Free Pumping Circuit

The Pfeiffer HiPace turbo pump has magnetic bearings for minimum wear and an expected life time approaching 100,000 hours and is UL certified.
The Oxford Instruments model is optimised for helium gas to ensure the lowest possible still temperature.

Adixen dry multi-stage roots pump from Pfeiffer, is renowned for its high reliability in the semiconductor industry and is UL certified. Roots pump benefits from a higher pumping speed than many alternative pumps, which means less strain on the turbo pump.

Double-diaphragm compressor from KNF, a high specification version, developed specifically for Oxford Instruments. It is UL certified and capable of operating at very high outlet pressures of 4 bar, which provides extra safety in the event of a partial restriction developing in the cold section of the condensing line. Its unique double-diaphragm design offers an extra layer of protection against loss of mixture (absent in any other pumping technology). It is also a cleaner technology, for example, compared to scroll pumps, which generate dust from the tip seal. One of the advantages of dry dilution refriegrators over wet dilution refrigerators is that there is more space available for customer wiring. The Triton offers 3 line of sight ports for high frequency coaxial lines or other custom services and 3 non-line of sight ports giving access for a variety of flexible wiring options.

• 24 way DC looms – Constantan or Cu/NbTi twisted pairs
• S1 flexible coaxial lines – for use up to 500 MHz
• Thermal clamping at PT1, PT2, Still, 100 mK and mixing chamber
• Current leads for superconducting magnets
• Wiring to suit commercially available nano-positioning devices
• Custom services and optical fibres available

The three line of sight ports available for high frequency coaxial lines or other custom services can be configured as two off KF40 and one off KF50 vacuum fittings, fully termintated for high frequency applications or blanked for customer fittings. In addition, a 65 mm central access LOS port is available for top loading sample access.

• UT85 semi-rigid coaxial lines
• Stainless steel inner / stainless steel outer conductor with PTFE insulation (UT85-SS-SS)
• Beryllium Copper inner / stainless steel outer conductor with PTFE insulation (UT85-B-SS)
• Niobium inner / Niobium outer conductor with PTFE insulation (UT85-Nb-Nb) from Still to mixing chamber
• Heatsinking at PT1, PT2, Still, 100 mK and mixing chamber
• SMA termination for frequencies up to 18 GHz
• SK termination for frequencies up to 40 GHz
• 20, 10, 6 dB attenuators at PT1, PT2 and Still plates available
• Optional noise thermometry
• Custom services and optical fibres available

Weak phonon-electron interactions at low temperatures make electron system cooling problematic in many applications. Fast pulse sequences for signal control is necessary in many areas of modern physics with corresponding high bandwidth wiring required. When working in the GHz frequency range, it is important to filter background blackbody radiation in the lines before it reaches the sample. Working with many of our customers, we have developed extensive high frequency wiring options with signal attenuation and heatsinking, to minimise electron temperatures on the sample or device.

• Semi-rigid coaxial cables with frequency ranges up to 40 GHz
• Heatsinking of outer conductor at all thermal plates
• Heatsinking of inner conductor and filtering of blackbody radiation using attenuators