Negative exchange interaction in Si quantum dot arrays via valley-phase induced ${\mathbb{Z}}_2$ gauge field

Abstract

The exchange interaction $J$ offers a powerful tool for quantum computation based on semiconductor spin qubits. However, the exchange interaction in two-electron systems in the absence of a magnetic field is usually constrained to be non-negative $J\ge 0$, which inhibits the construction of various dynamically corrected exchange-based gates. In this work, we show that negative exchange $J<0$ can be realized in two-electron Si quantum dot arrays in the absence of a magnetic field due to the presence of the valley degree of freedom. Here, valley phase differences between dots produce a non-trivial ${\mathbb{Z}}_2$ gauge field in the low-energy effective theory, which in turn can lead to a negative exchange interaction. In addition, we show that this ${\mathbb{Z}}_2$ gauge field can break Nagaoka ferromagnetism and be engineered by altering the occupancy of the dot array. Therefore, our work uncovers new tools for exchange-based quantum computing and a novel setting for studying quantum magnetism.

arXiv comment11 pages (7 main, 4 appendices) and 7 figures

References in corpus (46)

• Quantum Computation with Quantum Dots
• Topological Photonics
• Surface codes: Towards practical large-scale quantum computation
• Artificial gauge potentials for neutral atoms
• Coupled quantum dots as quantum gates
• Topological Acoustics
• Silicon Quantum Electronics
• Topological Bands for Ultracold Atoms
• Semiconductor Spin Qubits
• Computing with spin qubits at the surface code error threshold
• Fast universal quantum control above the fault-tolerance threshold in silicon
• Topological acoustics
• Prospects for Spin-Based Quantum Computing
• Universal quantum computation with spin-1/2 pairs and Heisenberg exchange
• Quantum simulation of a Fermi-Hubbard model using a semiconductor quantum dot array
• Two-qubit silicon quantum processor with operation fidelity exceeding 99%
• Composite pulses for robust universal control of singlet-triplet qubits
• Review of performance metrics of spin qubits in gated semiconducting nanostructures
• Cotunneling Spectroscopy in Few-Electron Quantum Dots
• Universal logic with encoded spin qubits in silicon
• Dynamical Quantum Error Correction of Unitary Operations with Bounded Controls
• Noise-resistant control for a spin qubit array
• Robust quantum gates for singlet-triplet spin qubits using composite pulses
• Projectively enriched symmetry and topology in acoustic crystals
• Atomic fluctuations lifting the energy degeneracy in Si/SiGe quantum dots
• SiGe quantum wells with oscillating Ge concentrations for quantum dot qubits
• Practical Strategies for Enhancing the Valley Splitting in Si/SiGe Quantum Wells
• Universal control of four singlet-triplet qubits
• Classification of time-reversal-invariant crystals with gauge structures
• Negative spin exchange in a multielectron quantum dot
• Analog Quantum Simulation of the Dynamics of Open Quantum Systems with Quantum Dots and Microelectronic Circuits
• Probing resonating valence bonds on a programmable germanium quantum simulator
• Spin-orbit coupling and anisotropic exchange in two-electron double quantum dots
• Interface and electromagnetic effects in the valley splitting of Si quantum dots
• Negative exchange interactions in coupled few-electron quantum dots
• Hubbard model for spin-1 Haldane chains
• Spin-Valley Qubit Dynamics In Exchange Coupled Silicon Quantum Dots
• Coherent control of a triangular exchange-only spin qubit
• Interplay of exchange and superexchange in triple quantum dots
• Macroscopic quantum state in a semiconductor device
• Inverted Singlet-Triplet Qubit Coded on a Two-Electron Double Quantum Dot
• Valley splitting depending on the size and location of a silicon quantum dot
• Two-dimensional Si spin qubit arrays with multilevel interconnects
• Spin-1 Haldane chains of superconductor-semiconductor hybrids
• Highly tunable 2D silicon quantum dot array with coupling beyond nearest neighbors
• Projective symmetry determined topology in flux Su-Schrieffer-Heeger model