An ultra-stable 1.5 T permanent magnet assembly for qubit experiments at cryogenic temperatures
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Magnetic fields are a standard tool in the toolbox of every physicist and are required for the characterization of materials, as well as the polarization of spins in nuclear magnetic resonance or electron paramagnetic resonance experiments. Quite often, a static magnetic field of sufficiently large, but fixed, magnitude is suitable for these tasks. Here, we present a permanent magnet assembly that can achieve magnetic field strengths of up to 1.5 T over an air gap length of 7 mm. The assembly is based on a Halbach array of neodymium magnets, with the inclusion of the soft magnetic material Supermendur to boost the magnetic field strength inside the air gap. We present the design, simulation, and characterization of the permanent magnet assembly, measuring an outstanding magnetic field stability with a drift rate of |D| < 2.8 ppb/h. Our measurements demonstrate that this assembly can be used for spin qubit experiments inside a dilution refrigerator, successfully replacing the more expensive and bulky superconducting solenoids.
| Original language | English |
|---|---|
| Article number | 085106 |
| Journal | Review of Scientific Instruments |
| Volume | 92 |
| Issue number | 8 |
| Number of pages | 9 |
| ISSN | 0034-6748 |
| DOIs | |
| Publication status | Published - 1 Aug 2021 |
Bibliographical note
Funding Information:
We are thankful to the team involved in the fabrication of the donor spin qubit devices used for the field stability test: Fay E. Hudson, Kohei M. Itoh, David N. Jamieson, A. Melwin Jakob, Brett C. Johnson, Jeffrey C. McCallum, and Andrew S. Dzurak. This research was funded by the Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology (Grant No. CE170100012) and the US Army Research Office (Contract No. W911NF-17-1-0200). We acknowledge the support of the Australian National Fabrication Facility (ANFF). A.L. and C.A. acknowledge the support through the UNSW Scientia Program. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the ARO or the US Government. The US Government is authorized to reproduce and distribute reprints for government purposes notwithstanding any copyright notation herein.
Publisher Copyright:
© 2021 Author(s).
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