Optically addressable nuclear spins in a solid with a six-hour coherence time

AbstractNuclear spins in semiconductors are leading candidates for future quantum technologies, including quantum computation, communication, and sensing. Nuclear spins in diamond are particularly attractive due to their long coherence time. With the nitrogen-vacancy (NV) centre, such nuclear qubits benefit from an auxiliary electronic qubit, which, at cryogenic temperatures, enables probabilistic entanglement mediated optically by photonic links. Here, we demonstrate a concept of a microelectronic quantum device at ambient conditions using diamond as wide bandgap semiconductor. The basic quantum processor unit – a single 14N nuclear spin coupled to the NV electron – is read photoelectrically and thus operates in a manner compatible with nanoscale electronics. The underlying theory provides the key ingredients for photoelectric quantum gate operations and readout of nuclear qubit registers. This demonstration is, therefore, a step towards diamond quantum devices with a readout area limited by inter-electrode distance rather than by the diffraction limit. Such scalability could enable the development of electronic quantum processors based on the dipolar interaction of spin-qubits placed at nanoscopic proximity.

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Coherence Time of Nuclear Spins in GaAs Quantum Well Probed by Submicron-Scale All-Electrical Nuclear Magnetic Resonance Device

Japanese Journal of Applied Physics ◽

10.1143/jjap.47.3115 ◽

2008 ◽

Vol 47 (4) ◽

pp. 3115-3117 ◽

Cited By ~ 1

Author(s):

Takeshi Ota ◽

Norio Kumada ◽

Go Yusa ◽

Sen Miyashita ◽

Toshimasa Fujisawa ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Quantum Well ◽

Coherence Time ◽

Nuclear Spins ◽

Submicron Scale ◽

Nuclear Magnetic

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Dipolar spin relaxation of divacancy qubits in silicon carbide

npj Computational Materials ◽

10.1038/s41524-021-00673-8 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Oscar Bulancea-Lindvall ◽

Nguyen T. Son ◽

Igor A. Abrikosov ◽

Viktor Ivády

Keyword(s):

Magnetic Field ◽

Silicon Carbide ◽

Relaxation Time ◽

Spin Relaxation ◽

Theoretical Study ◽

Coherence Time ◽

The Other ◽

Relaxation Processes ◽

Nuclear Spins ◽

Open Questions

AbstractDivacancy spins implement qubits with outstanding characteristics and capabilities in an industrial semiconductor host. On the other hand, there are still numerous open questions about the physics of these important defects, for instance, spin relaxation has not been thoroughly studied yet. Here, we carry out a theoretical study on environmental spin-induced spin relaxation processes of divacancy qubits in the 4H polytype of silicon carbide (4H-SiC). We reveal all the relevant magnetic field values where the longitudinal spin relaxation time T1 drops resonantly due to the coupling to either nuclear spins or electron spins. We quantitatively analyze the dependence of the T1 time on the concentration of point defect spins and the applied magnetic field and provide an analytical expression. We demonstrate that dipolar spin relaxation plays a significant role both in as-grown and ion-implanted samples and it often limits the coherence time of divacancy qubits in 4H-SiC.

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Coupling light to a nuclear spin gas with a two-photon linewidth of five millihertz

Science Advances ◽

10.1126/sciadv.abe9164 ◽

2021 ◽

Vol 7 (14) ◽

pp. eabe9164

Author(s):

Or Katz ◽

Roy Shaham ◽

Ofer Firstenberg

Keyword(s):

Noble Gas ◽

Optical Excitation ◽

Coherence Time ◽

Nuclear Spins ◽

Spin Coherence ◽

Coherent Interface ◽

Two Photon ◽

Alkali Atoms ◽

Optical Domain ◽

Photon Spectra

Nuclear spins of noble gases feature extremely long coherence times but are inaccessible to optical photons. Here, we realize a coherent interface between light and noble-gas spins that is mediated by alkali atoms. We demonstrate the optical excitation of the noble-gas spins and observe the coherent back action on the light in the form of high-contrast two-photon spectra. We report on a record two-photon linewidth of 5 ± 0.7 mHz above room temperature, corresponding to a 1-min coherence time. This experiment provides a demonstration of coherent bidirectional coupling between light and noble-gas spins, rendering their long-lived spin coherence accessible for manipulations in the optical domain.

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Gate fidelity and coherence of an electron spin in an Si/SiGe quantum dot with micromagnet

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1603251113 ◽

2016 ◽

Vol 113 (42) ◽

pp. 11738-11743 ◽

Cited By ~ 79

Author(s):

Erika Kawakami ◽

Thibaut Jullien ◽

Pasquale Scarlino ◽

Daniel R. Ward ◽

Donald E. Savage ◽

...

Keyword(s):

Quantum Dot ◽

Electron Spin ◽

Quantum Information Processing ◽

Coherence Time ◽

Nuclear Spins ◽

Quantum Bit ◽

Sige Quantum Dot ◽

Qubit Gate ◽

And Control ◽

Charge Noise

The gate fidelity and the coherence time of a quantum bit (qubit) are important benchmarks for quantum computation. We construct a qubit using a single electron spin in an Si/SiGe quantum dot and control it electrically via an artificial spin-orbit field from a micromagnet. We measure an average single-qubit gate fidelity of ∼99% using randomized benchmarking, which is consistent with dephasing from the slowly evolving nuclear spins in the substrate. The coherence time measured using dynamical decoupling extends up to ∼400 μs for 128 decoupling pulses, with no sign of saturation. We find evidence that the coherence time is limited by noise in the 10-kHz to 1-MHz range, possibly because charge noise affects the spin via the micromagnet gradient. This work shows that an electron spin in an Si/SiGe quantum dot is a good candidate for quantum information processing as well as for a quantum memory, even without isotopic purification.

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Decoherence-protected quantum register of nuclear spins in diamond

Quantum Science and Technology ◽

10.1088/2058-9565/ac49df ◽

2022 ◽

Author(s):

Francisco Javier González ◽

Raúl Coto

Keyword(s):

Quantum Information ◽

Coherence Time ◽

Nitrogen Vacancy ◽

Nuclear Spins ◽

Practical Applications ◽

Quantum Register ◽

Nitrogen Vacancy Center ◽

Simultaneous Control ◽

Gate Time ◽

And Control

Abstract Solid-state quantum registers are exceptional for storing quantum information at room temperature with long coherence time. Nevertheless, practical applications toward quantum supremacy require even longer coherence time to allow for more complex algorithms. In this work we propose a quantum register that lies in a decoherence-protected subspace to be implemented with nuclear spins nearby a Nitrogen-Vacancy center in diamond. The quantum information is encoded in two logical states composed of two Carbon-13 nuclear spins, while an electron spin is used as ancilla for initialization and control. Moreover, by tuning an off-axis magnetic field we enable non-nuclear-spin- preserving transitions that we use for preparing and manipulating the register through Stimulating Raman Adiabatic Passage. Furthermore, we consider more elaborated sequences to improve simultaneous control over the system yielding decreased gate time.

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Limit on Lorentz-Invariance- and CPT-Violating Neutron Spin Interactions Using a 3He-129Xe Comagnetometer

International Journal of Modern Physics Conference Series ◽

10.1142/s201019451660082x ◽

2016 ◽

Vol 40 ◽

pp. 1660082 ◽

Cited By ~ 1

Author(s):

F. Allmendinger ◽

U. Schmidt ◽

W. Heil ◽

S. Karpuk ◽

Yu. Sobolev ◽

...

Keyword(s):

Lorentz Invariance ◽

Background Field ◽

Coherence Time ◽

Neutron Spin ◽

Nuclear Spins ◽

Spin Coherence ◽

Spin Interactions ◽

Laboratory Reference Frame ◽

Background Fields ◽

Spin Coherence Time

We performed a search for a Lorentz-invariance- and CPT-violating coupling of the 3He and [Formula: see text]Xe nuclear spins to posited background fields. Our experimental approach is to measure the free precession of nuclear spin polarized 3He and [Formula: see text]Xe atoms using SQUIDs as detectors. As the laboratory reference frame rotates with respect to distant stars, we look for a sidereal modulation of the Larmor frequencies of the co-located spin samples. As a result we obtain an upper limit on the equatorial component of the background field [Formula: see text] GeV (68% C.L.). This experiment is currently the most precise test of spin anisotropy due to the excellent long spin-coherence time.

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