Electron Spin Coherence of Shallow Donors in Natural and Isotopically Enriched Germanium

Sigillito, A. J.; Jock, Ryan Michael; Tyryshkin, Alexei M.; Beeman, J. W.; Häller, E. E.; Itoh, Kohei M.; Lyon, S. A.

doi:10.1103/physrevlett.115.247601

Cited by 42 publications

(40 citation statements)

References 38 publications

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“…73 Ge [9,32,33]. This crystal was neutron transmutation doped to a density of 3 × 10 15 75 As donors/cm 3 .…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Here, we overcome this problem by substituting the ubiquitous semiconductor, silicon, with germanium. Germanium is a fundamentally different material that supports long coherence times [9], is insensitive to exchange oscillations [17], has higher mobilities (∼3x compared with Si) [18], and is gaining popularity for spintronics applications [19][20][21][22]. We measured the Stark effect for donors in germanium and found that it is substantially larger than in silicon.…”

Section: Introductionmentioning

confidence: 99%

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Large Stark tuning of donor electron spin qubits in germanium

et al. 2016

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Donor electron spins in semiconductors make exceptional quantum bits because of their long coherence times and compatibility with industrial fabrication techniques. Despite many advances in donor-based qubit technology, it remains difficult to selectively manipulate single donor electron spins. Here, we show that by replacing the prevailing semiconductor host material (silicon) with germanium, donor electron spin qubits can be electrically tuned by more than an ensemble linewidth, making them compatible with gate addressable quantum computing architectures. Using X-band pulsed electron spin resonance, we measured the Stark effect for donor electron spins in germanium. We resolved both spin-orbit and hyperfine Stark shifts and found that at 0.4 T, the spin-orbit Stark shift dominates. The spin-orbit Stark shift is highly anisotropic, depending on the electric field orientation relative to the crystal axes and external magnetic field. When the Stark shift is maximized, the spin-orbit Stark parameter is four orders of magnitude larger than in silicon. At select orientations a hyperfine Stark effect was also resolved and is an order of magnitude larger than in silicon. We report the Stark parameters for 75 As and 31 P donor electrons and compare them to the available theory. Our data reveal that 31 P donors in germanium can be tuned by at least four times the ensemble linewidth making germanium an appealing new host material for spin qubits that offers major advantages over silicon.

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“…73 Ge [9,32,33]. This crystal was neutron transmutation doped to a density of 3 × 10 15 75 As donors/cm 3 .…”

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Large Stark tuning of donor electron spin qubits in germanium

et al. 2016

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“…1 shows a density plot of the detuning of a Ge:P bulk spin with E 111 and B 0 = 0.4 T (corresponding to T 2 ≈ 1 ms as measured in Ref. 10) as a function of the electric field magnitude and the angle between E and B 0 . Strikingly, we show that qubit detunings above GHz could be attained within realistic experimental settings, thus allowing for nanosecond selective resonant manipulation -a two-orders-of-magnitude improvement to the maximum speed achievable with detuned Si donor spins.…”

Section: B Spin-orbit Stark Shiftsmentioning

confidence: 96%

“…Despite this decreased spin isolation, recent electron spin resonance (ESR) measurements of isotopically-purified-Ge donors have shown promising coherence times T 2 ∼ms 10 . Furthermore, Ge has been considered as a candidate host for transistor processing in the quantum regime 11 , and the technical development in device fabrication parallels the more popular Si electronics 12,13 .…”

Section: Introductionmentioning

confidence: 99%

Quantum gates with donors in germanium

Pica

Lovett

2016

Phys. Rev. B

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The possibility of quantum computing with spins in germanium nanoscale transistors has recently attracted interest since it promises highly tuneable qubits that have encouraging coherence times. We here present the first complete theory of the orbital states of Ge donor electrons, and use it to show that Ge could have significant advantages over silicon in the implementation of a donor-based quantum processor architecture. We show that the stronger spin-orbit interaction and the larger electron donor wave functions for Ge donors allow for greater tuning of the single qubit energy than for those in Si crystals, thus enabling a large speedup of selective (local) quantum gates. Further, exchange coupling between neighboring donor qubits is shown to be much larger in Ge than in Si, and we show that this greatly relaxes the precision in donor placement needed for robust two-qubit gates. To do this we compare two statistical distributions for Ge:P and Si:P pair couplings, corresponding to realistic donor implantation misplacement, and find that the spin couplings in Ge:P have a 33% chance of being within an order of magnitude of the largest coupling, compared with only 10% for the Si:P donors. This allows fast, parallel and robust architectures for quantum computing with donors in Ge.

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“…Besides being low-cost and readily-available substances that dominate the CMOS market, they possess highly desired features, such as long spin lifetimes and diffusion lengths [11,12]. Notably, the natural abundance of their spinless isotopes provides a clean environment, which is beneficial for the persistence of quantum information coherence [13]. Finally, wafer-scale epitaxy introduces confinement, alloying L-points of the Brillouin zone (L-valley).…”

Section: Introductionmentioning

confidence: 99%

Progress towards Spin-Based Light Emission in Group IV Semiconductors

et al. 2017

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Spin-optoelectronics is an emerging technology in which novel and advanced functionalities are enabled by the synergetic integration of magnetic, optical and electronic properties onto semiconductor-based devices. This article reviews the possible implementation and convergence of spintronics and photonics concepts on group IV semiconductors: the core materials of mainstream microelectronics. In particular, we describe the rapid pace of progress in the achievement of lasing action in the notable case of Ge-based heterostructures and devote special attention to the pivotal role played by optical investigations in advancing the understanding of the rich spin physics of group IV materials. Finally, we scrutinize recent developments towards the monolithic integration on Si of a new class of spin-based light emitting devices having prospects for applications in fields such as cryptography and interconnects.

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Electron Spin Coherence of Shallow Donors in Natural and Isotopically Enriched Germanium

Cited by 42 publications

References 38 publications

Large Stark tuning of donor electron spin qubits in germanium

Large Stark tuning of donor electron spin qubits in germanium

Quantum gates with donors in germanium

Progress towards Spin-Based Light Emission in Group IV Semiconductors

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