Isotope engineering of silicon and diamond for quantum computing and sensing applications

Itoh, Kohei M.; Watanabe, Hideyuki

doi:10.1557/mrc.2014.32

Cited by 190 publications

(176 citation statements)

References 172 publications

(405 reference statements)

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“…[8][9][10] In some proposals, the qubits are spin-1/2 29 Si nuclei in crystalline silicon and dipole coupling is used to implement two-qubit operations. 11,12 Achieving adequate coherence may depend on removing unwanted spins by isotopic purification, 8 and/or by active decoupling methods. 13 Accurate models of spin-spin interactions and many-body dynamics are essential to these ideas.…”

Section: -7mentioning

confidence: 99%

NMR line shape of Si29 in single-crystal silicon

Christensen

Price

2017

Phys. Rev. B

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We report measurements of the NMR lineshape of 4.685% abundant 29 Si in single-crystal silicon for four different crystallographic orientations relative to the applied magnetic field. To avoid significant inhomogeneous broadening, the sample crystals are immersed in a susceptibility matched liquid and the proton NMR lineshape in the liquid is used to measure the residual susceptibility mismatch and to shim the applied field. The observed lineshapes are in good agreement with disorder-averaged spin dynamics simulations performed on a 4 × 4 × 4 unit cell lattice with periodic boundary conditions. The splitting of resolved doublet features is used to measure the asymmetry ∆J of the nearest-neighbor indirect dipole or J-coupling tensor, with the result ∆J = 90 ± 20 Hz. All resolved doublets can be identified with specific nearest and next-nearest neighbor isolated spin pairs that occur in the disorder ensemble.

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Section: -7mentioning

confidence: 99%

NMR line shape of Si29 in single-crystal silicon

Christensen

Price

2017

Phys. Rev. B

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“…Donors in silicon have the further benefits of low spin-orbit coupling and dominance of spin-zero isotopes in the crystal lattice [12], limiting electric and magnetic decoherence sources, respectively. In the present device, isotopic enrichment of spin-zero 28 Si in the silicon substrate was used to further reduce magnetic decoherence [11,13].…”

Section: Introductionmentioning

confidence: 99%

A single-atom quantum memory in silicon

Freer

Simmons

Laucht

et al. 2017

Quantum Sci. Technol.

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Abstract. Long coherence times and fast gate operations are desirable but often conflicting requirements for physical qubits. This conflict can be resolved by resorting to fast qubits for operations, and by storing their state in a 'quantum memory' while idle. The 31 P donor in silicon comes naturally equipped with a fast qubit (the electron spin) and a long-lived qubit (the 31 P nuclear spin), coexisting in a bound state at cryogenic temperatures. Here, we demonstrate storage and retrieval of quantum information from a single donor electron spin to its host phosphorus nucleus in isotopically-enriched 28 Si. The fidelity of the memory process is characterised via both state and process tomography. We report an overall process fidelity F p ≈ 81%, a memory fidelity F m ≈ 92%, and memory storage times up to 80 ms. These values are limited by a transient shift of the electron spin resonance frequency following highpower radiofrequency pulses. ‡ Present address:

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“…Furthermore, silicon can be isotopically enriched and chemically purified to 28 Si, thereby removing nuclear spin background fluctuations and so silicon is often referred to as a semiconductor vacuum 2 . These two facts have motivated intense research on silicon qubits, leading to recent realizations of single-qubit [3][4][5][6][7] and two-qubit 8 logic gates.…”

mentioning

confidence: 99%

Spin-orbit coupling and operation of multivalley spin qubits

et al. 2015

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Spin qubits composed of either one or three electrons are realized in a quantum dot formed at a Si/SiO2 interface in isotopically enriched silicon. Using pulsed electron spin resonance, we perform coherent control of both types of qubits, addressing them via an electric field dependent g-factor. We perform randomized benchmarking and find that both qubits can be operated with high fidelity. Surprisingly, we find that the gfactors of the one-electron and three-electron qubits have an approximately linear but opposite dependence as a function of the applied dc electric field. We develop a theory to explain this g-factor behavior based on the spinvalley coupling that results from the sharp interface. The outer "shell" electron in the three-electron qubit exists in the higher of the two available conduction-band valley states, in contrast with the one-electron case, where the electron is in the lower valley. We formulate a modified effective mass theory and propose that inter-valley spin-flip tunneling dominates over intra-valley spin-flips in this system, leading to a direct correlation between the spin-orbit coupling parameters and the g-factors in the two valleys. In addition to offering all-electrical tuning for single-qubit gates, the g-factor physics revealed here for one-electron and three-electron qubits offers potential opportunities for new qubit control approaches.

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Isotope engineering of silicon and diamond for quantum computing and sensing applications

Cited by 190 publications

References 172 publications

NMR line shape of Si29 in single-crystal silicon

NMR line shape of Si29 in single-crystal silicon

A single-atom quantum memory in silicon

Spin-orbit coupling and operation of multivalley spin qubits

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