An ultra-stable 1.5 tesla permanent magnet assembly for qubit experiments at cryogenic temperatures

Abstract

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 1.5T over an air gap length of 7mm. The assembly is based on a Halbach array of neodymium (NdFeB) 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.

arXiv comment10 pages, 5 figures

References in corpus (18)

• Quantum sensing
• The nitrogen-vacancy colour centre in diamond
• Spins in few-electron quantum dots
• High-sensitivity diamond magnetometer with nanoscale resolution
• Single-shot read-out of an individual electron spin in a quantum dot
• Single-shot readout of an electron spin in silicon
• A programmable two-qubit quantum processor in silicon
• Storing quantum information for 30 seconds in a nanoelectronic device
• A four-qubit germanium quantum processor
• Silicon quantum processor unit cell operation above one Kelvin
• Semiconductor Qubits In Practice
• Electrically controlling single spin qubits in a continuous microwave field
• Low-frequency spin qubit detuning noise in highly purified ${}^{28}$Si/SiGe
• Quantum Theory of Rare-Earth Magnets
• Donor spins in silicon for quantum technologies
• Conditional quantum operation of two exchange-coupled single-donor spin qubits in a MOS-compatible silicon device
• Vibration-induced electrical noise in a cryogen-free dilution refrigerator: characterization, mitigation, and impact on qubit coherence
• Vibration-induced field fluctuations in a superconducting magnet

Cited by in corpus (7)

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• Fast coherent control of an NV- spin ensemble using a KTaO3 dielectric resonator at cryogenic temperatures
• Resonant two-laser spin-state spectroscopy of a negatively charged quantum dot-microcavity system with a cold permanent magnet
• Dark Exciton Giant Rabi Oscillations with no External Magnetic Field
• Novel permanent magnet array geometries for scalable trapped-ion quantum computing in a laser-free entanglement architecture
• Electron readout contrast enhancement in the parallel nuclear regime of an exchange-coupled donor spin qubit system