Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting

2013/02/28 by Chih Hwan Yang, C. H. Yang, A. Rossi +16 · 5 citations
Engineering · Physics and Astronomy · #Advancements in Semiconductor Devices and Circuit Design #Atomic physics #Condensed matter physics #Electron #Magnetic field #Optoelectronics #Physics #Quantum #Quantum and electron transport phenomena #Quantum computer #Quantum dot #Quantum mechanics #Quantum well #Qubit #Relaxation (psychology) #Semiconductor materials and devices #Silicon #Spin (aerodynamics) #Spin polarization #Zeeman effect #Zero field splitting #cond-mat.mes-hall

paper · pdf · doi:10.1038/ncomms3069

published as Nature Communications 4:2069 (2013) · 17 pages, 6 figures (main manuscript and supplementary material)

arxiv created 2013/05/30 · openalex publication_date 2013/06/27 · arxiv updated 2013/07/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06

Abstract

Although silicon is a promising material for quantum computation, the degeneracy of the conduction band minima (valleys) must be lifted with a splitting sufficient to ensure formation of well-defined and long-lived spin qubits. Here we demonstrate that valley separation can be accurately tuned via electrostatic gate control in a metal-oxide-semiconductor quantum dot, providing splittings spanning 0.3 - 0.8 meV. The splitting varies linearly with applied electric field, with a ratio in agreement with atomistic tight-binding predictions. We demonstrate single-shot spin readout and measure the spin relaxation for different valley configurations and dot occupancies, finding one-electron lifetimes exceeding 2 seconds. Spin relaxation occurs via phonon emission due to spin-orbit coupling between the valley states, a process not previously anticipated for silicon quantum dots. An analytical theory describes the magnetic field dependence of the relaxation rate, including the presence of a dramatic rate enhancement (or hot-spot) when Zeeman and valley splittings coincide.

Citations

• Lifetime measurements (T1) of electron spins in Si/SiGe quantum dots
• Spin relaxation and anticrossing in quantum dots: Rashba versus Dresselhaus spin-orbit coupling
• A single-atom electron spin qubit in silicon
• Physical mechanisms of interface-mediated intervalley coupling in Si
• Valley splitting in the silicon inversion layer: Misorientation effects
• Spin and valley-orbit splittings inSiGe∕Siheterostructures
• Theory of single electron spin relaxation in Si/SiGe lateral coupled quantum dots
• Magnetic field dependence of valley splitting in realistic Si∕SiGe quantum wells
• Measurement of valley splitting in high-symmetry Si/SiGe quantum dots
• Theory of Phonon-Induced Spin Relaxation in Laterally Coupled Quantum Dots
• Intervalley coupling for interface-bound electrons in silicon: An effective mass study
• Lifetime-Enhanced Transport in Silicon due to Spin and Valley Blockade
• Singlet-triplet relaxation in multivalley silicon single quantum dots
• Spins in few-electron quantum dots
• Single-shot read-out of an individual electron spin in a quantum dot

Cited by

• SiGe/Si(111)/SiGe heterostructure for Si spin qubits with electrons confined in L valley of conduction band
• Scalable Gate Architecture for a One-Dimensional Array of Semiconductor Spin Qubits
• Dynamical second-order noise sweetspots in resonantly driven spin qubits
• Strong spin-orbit interaction and g-factor renormalization of hole spins in Ge/Si nanowire quantum dots
• Spin Relaxation Benchmarks and Individual Qubit Addressability for Holes in Quantum Dots