Valley Phase and Voltage Control of Coherent Manipulation in Si Quantum Dots

Abstract

With any roughness at the interface of an indirect-bandgap semiconducting dot, the phase of the valley-orbit coupling can take on a random value. This random value, in double quantum dots, causes a large change in the exchange splitting. We demonstrate a simple analytical method to calculate the phase, and thus the exchange splitting and singlet-triplet qubit frequency, for an arbitrary interface. We then show that, with lateral control of the position of a quantum dot using a gate voltage, the valley-orbit phase can be controlled over a wide range, so that variations in the exchange splitting can be controlled for individual devices. Finally, we suggest experiments to measure the valley phase and the concomitant gate voltage control.

9 pages, 5 figures

References in corpus (6)

• An addressable quantum dot qubit with fault-tolerant control fidelity
• Physical mechanisms of interface-mediated intervalley coupling in Si
• Magnetic field dependence of valley splitting in realistic Si/SiGe quantum wells
• An electrically driven spin qubit based on valley mixing
• Control of valley dynamics in silicon quantum dots in the presence of an interface step
• Second Harmonic Coherent Driving of a Spin Qubit in a Si/SiGe Quantum Dot

Cited by in corpus (12)

• Multicore Quantum Computing
• Detuning Axis Pulsed Spectroscopy of Valley-Orbital States in Si/SiGe Quantum Dots
• A quadrupolar exchange-only spin qubit
• Coherent spin-valley oscillations in silicon
• Effects of Interface Steps on the Valley Orbit coupling in a Si/SiGe quantum dot
• Impact of valley phase and splitting on readout of silicon spin qubits
• Valley filtering and spatial maps of coupling between silicon donors and quantum dots
• Theory of valley-resolved spectroscopy of a Si triple quantum dot coupled to a microwave resonator
• Spin relaxation of a donor electron coupled to interface states
• Fast spin-valley-based quantum gates in Si with micromagnets
• On the validity of microscopic calculations of double-quantum-dot spin qubits based on Fock-Darwin states
• Impact of the valley orbit coupling on exchange gate for spin qubits in silicon quantum dots