Valley-enhanced fast relaxation of gate-controlled donor qubits in silicon

Abstract

Gate control of donor electrons near interfaces is a generic ingredient of donor-based quantum computing. Here, we address the question: how is the phonon-assisted qubit relaxation time $T_1$ affected as the electron is shuttled between the donor and the interface? We focus on the example of the `flip-flop qubit' [Tosi et al., arXiv:1509.08538v1], defined as a combination of the nuclear and electronic states of a phosphorous donor in silicon, promising fast electrical control and long dephasing times when the electron is halfway between the donor and the interface. We theoretically describe orbital relaxation, flip-flop relaxation, and electron spin relaxation. We estimate that the flip-flop qubit relaxation time can be of the order of $100\mu \text{s}$, 8 orders of magnitude shorter than the value for an on-donor electron in bulk silicon, and a few orders of magnitude shorter (longer) than the predicted inhomogeneous dephasing time (gate times). All three relaxation processes are boosted by (i) the nontrivial valley structure of the electron-phonon interaction, and (ii) the different valley compositions of the involved electronic states.

12 pages, 3 figures

References in corpus (8)

• Coherent control of a single electron spin with electric fields
• Spin-Orbit Mediated Control of Spin Qubits
• Electrically controlling single spin qubits in a continuous microwave field
• Quantum control of donor electrons at the Si-SiO2 interface
• Spin-spin coupling in electrostatically coupled quantum dots
• Charge dynamics and spin blockade in a hybrid double quantum dot in silicon
• Valley interference effects on a donor electron close to a Si/SiO2 interface
• Impact of the valley degree of freedom on the control of donor electrons near a Si/SiO_2 interface

Cited by in corpus (13)

• Silicon quantum processor with robust long-distance qubit couplings
• Quantum and Tunnelling Capacitance in Charge and Spin Qubits
• Addressable electron spin resonance using donors and donor molecules in silicon
• Large dispersive interaction between a CMOS double quantum dot and microwave photons
• Robust electric dipole transition at microwave frequencies for nuclear spin qubits in silicon
• Fast high-fidelity single-qubit gates for flip-flop qubits in silicon
• Hyperfine-assisted fast electric control of dopant nuclear spins in semiconductors
• Dephasing of Majorana qubits due to quasistatic disorder
• Hyperfine-assisted decoherence of a phosphorus nuclear-spin qubit in silicon
• Spin relaxation of a donor electron coupled to interface states
• Electron spin relaxations of phosphorus donors in bulk silicon under large electric field
• Fast spin-valley-based quantum gates in Si with micromagnets
• Four-state discrimination for a pair of spin qubits via gate reflectometry