Molecular formations and spectra due to electron correlations in three-electron hybrid double-well qubits

Abstract

We show that systematic full configuration-interaction (FCI) calculations enable prediction of the energy spectra and the intrinsic spatial and spin structures of the many-body wave functions as a function of the detuning parameter for the case of three-electron hybrid qubits based on GaAs asymmetric double quantum dots. Specifically, in comparison with the case of weak interactions and treating the entire three-electron double-dot hybrid qubit as an integral unit, it is shown that the predicted spectroscopic patterns, originating from strong electron correlations, manifest the formation of Wigner molecules (WMs). Signatures of WM formation include: (1) a strong suppression of the energy gaps relative to the non-interacting-electrons modeling, and (2) the appearance of a pair of avoided crossings arising between states associated with two-electron occupancies in the left and right wells. The Wigner molecule is a physical entity associated with electron localization within each well and it cannot be captured by the previously employed independent-particle or two-site-Hubbard theoretical modeling of the hybrid qubits. The emergence of strong WMs is investigated in depth through the concerted use of FCI-adapted diagnostic tools like charge and spin densities, as well as conditional probability distributions. Furthermore, the energy spectrum as a function of the strength of the Coulomb repulsion (at constant detuning) is calculated in order to complement the thorough analysis of the factors contributing to WM emergence. We report remarkable agreement with recent experimental measurements. The present FCI methodology for multi-well quantum dots can be straightforwardly extended to treat valleytronic two-band Si/SiGe hybrid qubits, where the central role of the WMs was confirmed recently.

arXiv commentPublished version. 16 pages with 9 color figures. For related publications, see https://sites.gatech.edu/cyannouleas/about/

References in corpus (50)

• Spins in few-electron quantum dots
• Coupled quantum dots as quantum gates
• Silicon Quantum Electronics
• Universal Quantum Computation with the Exchange Interaction
• Single-shot readout of an electron spin in silicon
• A four-qubit germanium quantum processor
• Two-qubit silicon quantum processor with operation fidelity exceeding 99%
• Quantum control and process tomography of a semiconductor quantum dot hybrid qubit
• Wigner Crystallization in mesoscopic 2D electron systems
• Fast two-qubit logic with holes in germanium
• Crossover from Fermi liquid to Wigner molecule behavior in quantum dots
• Self-Consistent Measurement and State Tomography of an Exchange-Only Spin Qubit
• Symmetry breaking and quantum correlations in finite systems: Studies of quantum dots and ultracold Bose gases and related nuclear and chemical methods
• A fast "hybrid" silicon double quantum dot qubit
• Collective Coulomb Blockade in an Array of Quantum Dots: A Mott-Hubbard Approach
• Fast sensing of double-dot charge arrangement and spin state with an rf sensor quantum dot
• Collective and independent-particle motion in two-electron artificial atoms
• Excitation spectrum of two correlated electrons in a lateral quantum dot with negligible Zeeman splitting
• Fast coherent manipulation of three-electron states in a double quantum dot
• Three-electron spin qubits
• Generic Hubbard model description of semiconductor quantum dot spin qubits
• High fidelity resonant gating of a silicon based quantum dot hybrid qubit
• Extending the coherence of a quantum dot hybrid qubit
• Tunable Hybrid Qubit in a GaAs Double Quantum Dot
• Pulse-gated quantum dot hybrid qubit
• A molecular state of correlated electrons in a quantum dot
• Quantum-dot lithium in zero magnetic field: Electronic properties, thermodynamics, and a liquid-solid transition in the ground state
• Hubbard model description of silicon spin qubits: charge stability diagram and tunnel coupling in Si double quantum dots
• Formation and control of electron molecules in artificial atoms: Impurity and magnetic-field effects
• Two-dimensional quantum-dot helium in a magnetic field: Variational theory
• Strong electron-electron interactions in Si/SiGe quantum dots
• Strongly correlated wave functions for artificial atoms and molecules
• Interplay of charge and spin coherence in Landau-Zener-Stückelberg-Majorana interferometry
• Coherent control and spectroscopy of a semiconductor quantum dot Wigner molecule
• Effective Hamiltonian for the hybrid double quantum dot qubit
• Three-electron anisotropic quantum dots in variable magnetic fields: exact results for excitation spectra, spin structures, and entanglement
• Readout Of Singlet-Triplet Qubits At Large Magnetic Field Gradients
• Spontaneous symmetry breaking in single and molecular quantum dots
• Single-shot readout of a driven hybrid qubit in a GaAs double quantum dot
• Double-well ultracold-fermions computational microscopy: Wave-function anatomy of attractive-pairing and Wigner-molecule entanglement and natural orbitals
• Two-body Wigner molecularization in asymmetric quantum dot spin qubits
• Ultracold few fermionic atoms in needle-shaped double wells: spin chains and resonating spin clusters from microscopic Hamiltonians emulated via antiferromagnetic Heisenberg and t-J models
• Spin blockade and coherent dynamics of high-spin states in a three-electron double quantum dot
• Artificial quantum-dot Helium molecules: Electronic spectra, spin structures, and Heisenberg clusters
• Electron and boson clusters in confined geometries: symmetry breaking in quantum dots and harmonic traps
• Nonuniversal transmission phase lapses through a quantum dot: An exact-diagonalization of the many-body transport problem
• A tunable hybrid qubit in a triple quantum dot
• Validity of the single-particle description and charge noise resilience for multielectron quantum dots
• Symmetry breaking and Wigner molecules in few-electron quantum dots
• Quantum dots based on parabolic quantum wells: importance of electronic correlations

Cited by in corpus (13)

• Strong hole-photon coupling in planar Ge for probing charge degree and strongly-correlated states
• Jellybean quantum dots in silicon for qubit coupling and on-chip quantum chemistry
• Quantum Wigner molecules in moiré materials
• Wigner-molecule supercrystal in transition-metal dichalcogenide moiré superlattices: Lessons from the bottom-up approach
• Wigner molecules in phosphorene quantum dots
• Valleytronic full configuration-interaction approach: An application to the excitation spectra of Si double-dot qubits
• Wigner-molecularization-enabled dynamic nuclear field programming
• Electronic Wigner-Molecule Polymeric Chains in Elongated Silicon Quantum Dots and Finite-Length Quantum Wires
• Crystal-field effects in the formation of Wigner-molecule supercrystals in moiré TMD superlattices
• True decoherence-free-subspace derived from a semiconductor double quantum dot Heisenberg spin-trimer
• Dressed basis sets for the modeling of exchange interactions in double quantum dots
• Wave-function microscopy: Derivation and anatomy of exact algebraic spinful wave functions and full Wigner-molecular spectra of a few highly correlated rapidly rotating ultracold fermionic atoms
• Artificial versus Natural Atoms: The uncanny capability of the many-body Schrödinger equation to produce emergent behavior