Measurement of the spin temperature of optically cooled nuclei and GaAs hyperfine constants in GaAs/AlGaAs quantum dots

Abstract

Deep cooling of electron and nuclear spins is equivalent to achieving polarization degrees close to 100% and is a key requirement in solid state quantum information technologies. While polarization of individual nuclear spins in diamond and SiC reaches 99% and beyond, it has been limited to 60-65% for the nuclei in quantum dots. Theoretical models have attributed this limit to formation of coherent "dark" nuclear spin states but experimental verification is lacking, especially due to the poor accuracy of polarization degree measurements. Here we measure the nuclear polarization in GaAs/AlGaAs quantum dots with high accuracy using a new approach enabled by manipulation of the nuclear spin states with radiofrequency pulses. Polarizations up to 80% are observed - the highest reported so far for optical cooling in quantum dots. This value is still not limited by nuclear coherence effects. Instead we find that optically cooled nuclei are well described within a classical spin temperature framework. Our findings unlock a route for further progress towards quantum dot electron spin qubits where deep cooling of the mesoscopic nuclear spin ensemble is used to achieve long qubit coherence. Moreover, GaAs hyperfine material constants are measured here experimentally for the first time.

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Cited by in corpus (37)

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• Ideal refocusing of an optically active spin qubit under strong hyperfine interactions
• Collective quantum memory activated by a driven central spin
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• Few-fermion thermometry
• Spin temperature concept verified by optical magnetometry of nuclear spins
• Dynamical suppression of fluctuations in an interacting nuclear spin bath of a self-assembled quantum dot using multiple pulse nuclear magnetic resonance
• Hyperfine interaction for holes in quantum dots: k.p model
• Approaching a fully-polarized state of nuclear spins in a semiconductor quantum dot
• Nuclear spin dynamics, noise, squeezing and entanglement in box model
• Cross-calibration of GaAs deformation potentials and gradient-elastic tensors using photoluminescence and nuclear magnetic resonance spectroscopy in GaAs/AlGaAs quantum dot structures
• Nuclear spin diffusion in the central spin system of a GaAs/AlGaAs quantum dot
• Direct measurement of hyperfine shifts and radiofrequency manipulation of the nuclear spins in individual CdTe/ZnTe quantum dots
• Warm-up spectroscopy of quadrupole-split nuclear spins in n-GaAs epitaxial layers
• Optical Resonance Shift Spin Noise Spectroscopy
• A many-body singlet prepared by a central spin qubit
• Electron-induced nuclear magnetic ordering in n-type semiconductors
• Nuclear spin cooling by helicity-alternated optical pumping at weak magnetic fields in $n$-GaAs
• Quantum memory assisted precision rotation sensing
• Quantum non-demolition measurement of an electron spin qubit through its low-energy many-body spin environment
• Topological quantum thermometry
• The formation of a nuclear-spin dark state in silicon
• Kinetic approach to the nuclear-spin polaron formation
• Third Stable Branch and Tristability of Nuclear Spin Polarization in Single Quantum Dot System
• Phonon-assisted carrier tunneling in coupled quantum dot systems with hyperfine-induced spin flip
• Shielding of external magnetic field by dynamic nuclear polarization in (In,Ga)As quantum dots
• MOVPE growth, transmission electron microscopy and magneto-optical spectroscopy of individual InAsP/GaInP quantum dots
• Hilbert Space Fragmentation and Subspace Scar Time-Crystallinity in Driven Homogeneous Central-Spin Models
• Noise-resistant quantum memory enabled by Hamiltonian engineering
• Superradiant-like dynamics by electron shuttling on a nuclear-spin island
• Giant Hyperfine Interaction between a Dark Exciton Condensate and Nuclei
• Quantum repeaters based on individual electron spins and nuclear-spin-ensemble memories in quantum dots
• Entangling nuclear spins in distant quantum dots via an electron bus
• Hyperfine interaction in atomically thin transition metal dichalcogenides
• Extending Qubit Coherence Time via Hybrid Dynamical Decoupling
• Nuclear spin polaron-formation: anisotropy effects and quantum phase transition
• Deep optical cooling of coupled nuclear spin-spin and quadrupole reservoirs in a GaAs/(Al,Ga)As quantum well