Optimisation of electrically-driven multi-donor quantum dot qubits

Abstract

Multi-donor quantum dots have been at the forefront of recent progress in Si-based quantum computation. Among them, $2P:1P$ qubits have a built-in dipole moment, enabling all-electrical spin operation via hyperfine mediated electron dipole spin resonance (EDSR). The development of all-electrical multi-donor dot qubits requires a full understanding of their EDSR and coherence properties, incorporating multi-valley nature of their ground state. Here, by introducing a variational effective mass wave-function, we examine the impact of qubit geometry and nearby charge defects on the electrical operation and coherence of $2P:1P$ qubits. We report four outcomes: (i) The difference in the hyperfine interaction between the $2P$ and $1P$ sites enables fast EDSR, with $T_{\pi }\sim 10-50$ ns and a Rabi ratio $(T_1/T_{\pi })\sim 10^6$. We analyse qubits with the $2P:1P$ axis aligned along the [100], [110] and [111] crystal axes, finding that the fastest EDSR time $T_{\pi }$ occurs when the $2P:1P$ axis is $\parallel$[111], while the best Rabi ratio occurs when it is $\parallel$ [100]. This difference is attributed to the difference in the wave function overlap between $2P$ and $1P$ for different geometries. In contrast, the choice of $2P$ axis has no visible impact on qubit operation. (ii) Sensitivity to random telegraph noise due to nearby charge defects depends strongly on the location of the nearby defects with respect to the qubit. For certain orientations of defects random telegraph noise has an appreciable effect both on detuning and $2P-1P$ tunneling, with the latter inducing gate errors. (iii) The qubit is robust against $1/f$ noise provided it is operated away from the charge anticrossing. (iv) Entanglement via exchange is several orders of magnitude faster than dipole-dipole coupling. These findings pave the way towards fast, low-power, coherent and scalable donor dot-based quantum computing.

23 pages, 6 figures

References in corpus (19)

• Graphene Spintronics
• Hyperfine-mediated gate-driven electron spin resonance
• Electric Dipole Spin Resonance for Heavy Holes in Quantum Dots
• Spin-Orbit Mediated Control of Spin Qubits
• Electrically controlling single spin qubits in a continuous microwave field
• Quantifying the quantum gate fidelity of single-atom spin qubits in silicon by randomized benchmarking
• Physical mechanisms of interface-mediated intervalley coupling in Si
• Fast Electrical Control of Single Electron Spins in Quantum Dots with Vanishing Influence from Nuclear Spins
• Theory of electric dipole spin resonance in quantum dots: Mean field theory with Gaussian fluctuations and beyond
• Decoherence induced by anisotropic hyperfine interaction in Si spin qubits
• Spin-spin coupling in electrostatically coupled quantum dots
• External field control of donor electron exchange at the Si/SiO2 interface
• Singlet-Triplet Relaxation in Two-electron Silicon Quantum Dots
• Spin-lattice relaxation times of single donors and donor clusters in silicon
• Valley interference and spin exchange at the atomic scale in silicon
• Characterization and Suppression of Low-frequency Noise in Si/SiGe Quantum Point Contacts and Quantum Dots
• Decoherence of an exchange qubit by hyperfine interaction
• Suppression of low-frequency noise in two-dimensional electron gas at degenerately doped Si:P δ-layers
• Multi-valley envelope function equations and effective potentials for P impurity in silicon

Cited by in corpus (2)

• Electrical operation of hole spin qubits in planar MOS silicon quantum dots
• Micromagnet-free operation of electron spin qubits in Si/Si${}_{1-x}$Ge${}_x$ vertical double quantum dots