Spin relaxation in a single-electron graphene quantum dot

Abstract

The relaxation time of a single-electron spin is an important parameter for solid-state spin qubits, as it directly limits the lifetime of the encoded information. Thanks to the low spin-orbit interaction and low hyperfine coupling, graphene and bilayer graphene (BLG) have long been considered promising platforms for spin qubits. Only recently, it has become possible to control single-electrons in BLG quantum dots (QDs) and to understand their spin-valley texture, while the relaxation dynamics have remained mostly unexplored. Here, we report spin relaxation times ($T_1$) of single-electron states in BLG QDs. Using pulsed-gate spectroscopy, we extract relaxation times exceeding 200 $\mu$s at a magnetic field of 1.9 T. The $T_1$ values show a strong dependence on the spin splitting, promising even longer $T_1$ at lower magnetic fields, where our measurements are limited by the signal-to-noise ratio. The relaxation times are more than two orders of magnitude larger than those previously reported for carbon-based QDs, suggesting that graphene is a potentially promising host material for scalable spin qubits.

4 figures 5 pages

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• Pulsed-gate spectroscopy of single-electron spin states in bilayer graphene quantum dots
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• Counting Statistics of Single Electron Transport in Bilayer Graphene Quantum Dots
• Coherent Charge Oscillations in a Bilayer Graphene Double Quantum Dot
• Spin-valley locked excited states spectroscopy in a one-particle bilayer graphene quantum dot
• Materials for Quantum Technologies: a Roadmap for Spin and Topology
• Collective excitations in chiral Stoner magnets
• Extended Hubbard model describing small multi-dot arrays in bilayer graphene
• Pauli blockade catalogue and three- and four-particle Kondo effect in bilayer graphene quantum dots
• Switching spin filling sequence in a bilayer graphene quantum dot through trigonal warping
• Tunable p-n junction barriers in few-electron bilayer graphene quantum dots
• Dipole coupling of a bilayer graphene quantum dot to a high-impedance microwave resonator
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• Three-carrier spin blockade and coupling in bilayer graphene double quantum dots
• Phonon-limited valley life times in single-particle bilayer graphene quantum dots
• Electrically-tunable graphene nanomechanical resonators
• Tunable spin-orbit splitting in bilayer graphene/WSe${}_2$ quantum devices
• Encoding quantum bits in bound electronic states of a graphene nanotorus
• Tuning confined states and valley g-factors by quantum dot design in bilayer graphene
• RFSoC-based radio-frequency reflectometry in gate-defined bilayer graphene quantum devices
• High mobility transport in isotopically-enriched ${}^{12}$C and ${}^{13}$C exfoliated graphene
• Ultra-Fast All-Electrical Universal Nano-Qubits
• Fabrication and Characterization of Magnetic-Field-Resilient MoRe Superconducting Coplanar Waveguide Resonators
• Spin polarised quantised transport via one-dimensional nanowire-graphene contacts
• The role of antisymmetric orbitals and electron-electron interactions on the two-particle spin and valley blockade in graphene double quantum dots
• Increasing the proximity induced spin-orbit coupling in bilayer graphene/WSe${}_2$ heterostructures with pressure
• Direct measurement of spin-flip rates in single-electron tunneling
• Radio-frequency charge detection on graphene electron-hole double quantum dots
• Quantum-Hall Spectroscopy of Elliptically Deformed Graphene Nanobubble Qubits