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Notch filtering the nuclear environment of a spin qubit
Filip K Malinowski1, Frederico Martins1, Peter D Nissen1
1Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark.
Nature Nanotechnology
|November 8, 2016
Summary
Researchers filtered nuclear spin noise in gallium arsenide quantum dots. This significantly improved electron spin qubit coherence times, achieving 0.87 ms, a major advance for quantum computing.
Area of Science:
- Quantum Information Science
- Condensed Matter Physics
- Materials Science
Background:
- Electron spins in gate-defined quantum dots are a leading platform for quantum computation.
- Gallium arsenide offers high-quality materials and precise qubit operations for spin-based quantum computing.
- Hyperfine interaction with nuclear spins in the host lattice causes magnetic noise, leading to decoherence.
Purpose of the Study:
- To investigate and mitigate low- and high-frequency nuclear spin noise in gallium arsenide quantum dots.
- To enhance the coherence times of electron spin qubits.
- To demonstrate the effectiveness of dynamical decoupling techniques for filtering nuclear noise.
Main Methods:
- Utilized dynamical decoupling sequences, specifically nuclear notch filtering, to suppress magnetic noise.
- Investigated the impact of low-frequency noise (10 ns dephasing) and high-frequency noise (related to isotope Larmor precession).
- Measured spin coherence times (T2) to quantify the enhancement.
Main Results:
- Successfully filtered both low- and high-frequency nuclear noise using tailored dynamical decoupling.
- Achieved a spin coherence time (T2) of 0.87 ms, a five-order-of-magnitude improvement over typical gate times.
- Demonstrated coherence times exceeding those reported for Si/SiGe gate-defined quantum dots.
Conclusions:
- Dynamical decoupling sequences, including nuclear notch filtering, are effective in combating nuclear spin noise.
- Significant enhancement of spin qubit coherence times is achievable in gallium arsenide quantum dots.
- This work represents a substantial step towards robust quantum computation using electron spins.
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