Effects of valley splitting on resonant-tunneling readout of spin qubits

Abstract

The effect of valley splitting on the readout of qubit states is theoretically investigated in a three-quantum-dot (QD) system. A single unit of the three-QD system consists of qubit-QDs and a channel-QD that is connected to a conventional transistor. The nonlinear source--drain current characteristics under resonant-tunneling effects are used to distinguish different qubit states. Using nonequilibrium Green functions, the current formula for the three-QD system is derived when each QD has two valley energy levels. Two valley states in each QD are considered to be affected by variations in the fabrication process. We found that when valley splitting is smaller than Zeeman splitting, the current nonlinearity can improve the readout, provided that the nonuniformity of the valley energy levels is small. Conversely, when the valley splitting is larger than the Zeeman splitting, the nonuniformity degraded the readout. In both cases, we showed that there are regions where the measurement time $t_{\mathrm{meas}}$ is much less than the decoherence time $t_{\mathrm{dec}}$ such that $t_{\mathrm{dec}}/t_{\mathrm{meas}}>100$. This suggests that less than 1\% measurement error is anticipated, which opens up the possibility for implementing surface codes even in the presence of valley splitting.

arXiv comment17 pages, 18 figures

References in corpus (38)

• Quantum Computation with Quantum Dots
• Surface codes: Towards practical large-scale quantum computation
• Quantum state engineering with Josephson-junction devices
• Time-dependent transport in interacting and non-interacting mesoscopic systems
• Single-shot read-out of an individual electron spin in a quantum dot
• Silicon Quantum Electronics
• Suppressing quantum errors by scaling a surface code logical qubit
• A Two Qubit Logic Gate in Silicon
• Silicon CMOS architecture for a spin-based quantum computer
• Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting
• A Crossbar Network for Silicon Quantum Dot Qubits
• Controllable valley splitting in silicon quantum devices
• The Resonant Exchange Qubit
• A fault-tolerant addressable spin qubit in a natural silicon quantum dot
• Gate-based single-shot readout of spins in silicon
• Single Spin Dynamics and Decoherence in a Quantum Dot via Charge Transport
• Valley-based noise-resistant quantum computation using Si quantum dots
• Electron spin resonance and spin-valley physics in a silicon double quantum dot
• Fast coherent manipulation of three-electron states in a double quantum dot
• A shuttling-based two-qubit logic gate for linking distant silicon quantum processors
• Suppression of current in transport through parallel double quantum dots
• Repetitive single electron spin readout in silicon
• Valley dependent anisotropic spin splitting in silicon quantum dots
• Single-shot single-gate RF spin readout in silicon
• Practical Strategies for Enhancing the Valley Splitting in Si/SiGe Quantum Wells
• Valley splitting of single-electron Si MOS quantum dots
• Giant anisotropy of spin relaxation and spin-valley mixing in a silicon quantum dot
• Low disorder and high valley splitting in silicon
• The critical role of substrate disorder in valley splitting in Si quantum wells
• A quadrupolar exchange-only spin qubit
• Quantum computing on long-lived donor states of Li in Si
• Spin-polarized transport in II-VI magnetic resonant tunneling devices
• Spin-Valley Qubit Dynamics In Exchange Coupled Silicon Quantum Dots
• Mediated gates between spin qubits
• Valley-Free Silicon Fins Caused by Shear Strain
• Readout using Resonant Tunneling in Silicon Spin Qubits
• Leveraging Off-the-Shelf Silicon Chips for Quantum Computing
• Five and three quantum dot systems as apparatuses for measuring energy-levels