Low-power multipulse line narrowing in solid-state NMR

Burum, D. P.; Linder, Max; Ernst, R. R.

doi:10.1016/0022-2364(81)90200-6

Cited by 153 publications

(157 citation statements)

References 23 publications

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“…The atomic systems shown -trapped ions and molecular nuclei in liquid solution -have already been employed for small quantum algorithms [6,13]; not coincidentally, they show very high values of Q, the product of the qubit frequency ω 0 /2π and πT 2 . Most solid-state qubits show smaller values of Q; as we demonstrate in this Letter, however, the long coherence times we observe in solid-state 29 Si nuclei afford them a Q and ΩT 2 as high or higher than atomic systems, indicating this system's promise for solid-state quantum computing.…”

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confidence: 52%

Coherence time of decoupled nuclear spins in silicon

et al. 2005

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We report NMR experiments using high-power, RF decoupling techniques to show that a 29 Si nuclear spin qubit in a solid silicon crystal at room temperature can preserve quantum phase for 10 9 precessional periods. The coherence times we report are longer than for any other observed solid-state qubit by more than four orders of magnitude. In high quality crystals, these times are limited by residual dipolar couplings and can be further improved by isotopic depletion. In defect-heavy samples, we provide evidence for decoherence limited by 1/f noise. These results provide insight toward proposals for solid-state nuclear-spin-based quantum memories and quantum computers based on silicon.PACS numbers: 03.67. Lx, 03.67.Pp, 76.60.Lz, 82.56.Jn Quantum information processing devices outperform their classical counterparts by preserving and exploiting the correlated phases of their constituent quantum oscillators, which are usually two-state systems called "qubits." An increasing number of theoretical proposals have shown that such devices allow secure long-distance communication and improved computational power [1]. Solid-state implementations of these devices are favored for reasons of both scalability and integration with existing hardware, although previous experiments have shown limited coherence times for solid-state qubits. The development of quantum error correcting codes [2] and fault tolerant quantum computation [3] showed that largescale quantum algorithms are still theoretically possible in the presence of decoherence. However, the coherence time must be dauntingly long: approximately 10 5 times the duration of a single quantum gate, and probably longer depending on the quantum computer architecture [1]. The question of whether a scalable implementation can surpass this coherence threshold is not only important for the technological future of quantum computation, but also for fundamental understanding of the border between microscopic quantum behavior and macroscopic classical behavior.Experimentally observed coherence times (T 2 ) for various qubit implementations are shown in Table I. The atomic systems shown -trapped ions and molecular nuclei in liquid solution -have already been employed for small quantum algorithms [6,13]; not coincidentally, they show very high values of Q, the product of the qubit frequency ω 0 /2π and πT 2 . Most solid-state qubits show smaller values of Q; as we demonstrate in this Letter, however, the long coherence times we observe in solid-state 29 Si nuclei afford them a Q and ΩT 2 as high or higher than atomic systems, indicating this system's promise for solid-state quantum computing.Many promising qubits and coherence time measurements are not mentioned in Table I either because reliable experimental data are not available, or because the existing experimental data are taken under conditions not sufficiently similar to the corresponding quantum computer architecture. For example, electron spins bound to phosphorous donors in pure, isotopically depleted silicon also show prom...

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confidence: 52%

Coherence time of decoupled nuclear spins in silicon

et al. 2005

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“…The first approach was introduced in NMR, e.g. for designing high-performance homonuclear decoupling sequences [38][39][40][41][42][43] or in high-resolution heteronuclear decoupling [31][32][33][35][36][37]. Examples of DD sequences that can be constructed using this approach are the XY-8 and XY-16 sequences [36].…”

Section: (C) Combining Basic Cyclesmentioning

confidence: 99%

“…This is the case of a homonuclear system where the general form of the coupling must be retained and it can induce flips of the system qubit as well as dephasing. In this case, decoupling will generally affect the complete system plus 'bath' [38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Robust dynamical decoupling

Souza

Álvarez

Suter

2012

Phil. Trans. R. Soc. A.

194

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Quantum computers, which process information encoded in quantum mechanical systems, hold the potential to solve some of the hardest computational problems. A substantial obstacle for the further development of quantum computers is the fact that the lifetime of quantum information is usually too short to allow practical computation. A promising method for increasing the lifetime, known as dynamical decoupling (DD), consists of applying a periodic series of inversion pulses to the quantum bits. In the present review, we give an overview of this technique and compare different pulse sequences proposed earlier. We show that pulse imperfections, which are always present in experimental implementations, limit the performance of DD. The loss of coherence due to the accumulation of pulse errors can even exceed the perturbation from the environment. This effect can be largely eliminated by a judicious design of pulses and sequences. The corresponding sequences are largely immune to pulse imperfections and provide an increase of the coherence time of the system by several orders of magnitude.

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“…By contrast to ensemble magnetization (that decays with T 1 ), here the relevant time scale is the ensemble T 2 * time that is about 10 ms in diamond with natural 13 C abundance 22 and agrees reasonably with the observed decoherence time. For future increase of the coherence time, such dipole interactions between nuclei of the same species can be efficiently removed by homonuclear decoupling schemes 9,[23][24][25] . Other sources of decoherence could be paramagnetic or nuclear spin impurities at the surface whose decoherence effects could be avoided by isolating ST1 defects in the bulk crystal.…”

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confidence: 99%

Readout and control of a single nuclear spin with a metastable electron spin ancilla

Lee¹,

Widmann²,

Rendler³

et al. 2013

Nature Nanotech

121

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Electron and nuclear spins associated with point defects in insulators are promising systems for solid state quantum technology [1][2][3] . While the electron spin usually is used for readout and addressing, nuclear spins are exquisite quantum bits 4,5 and memory systems 3,6 . With these systems single-shot readout of nearby nuclear spins 5 as well as entanglement 4,7,8 aided by the electron spin has been shown. While the electron spin in this example is essential for readout it usually limits nuclear spin coherence 9. This has set of the quest for defects with spin-free ground states 8,10 . Here, we isolate a hitherto unidentified defect in diamond and use it at room temperature to demonstrate optical spin polarization and readout with exceptionally high contrast (up to 45%), coherent manipulation of an individual excited triplet state spin, and coherent nuclear spin manipulation using the triplet electron spin as a meta-stable ancilla. By this we demonstrate nuclear magnetic resonance and Rabi oscillations of the uncoupled nuclear spin in the spin-free electronic ground state. Our study demonstrates that nuclei coupled to single metastable electron spins are useful quantum systems with long memory times despite electronic relaxation processes.Coupled electron and nuclear spins in solids are promising candidates for quantum memories and registers and present a particular class in the emerging field of hybrid quantum systems 7,[11][12][13][14] , in which different types of qubits perform distinct functions according to their advantageous properties. In this particular case, the nuclear spin, which is weakly coupled to the environment, serves as a long-lived arXiv:1302.4608v1 [quant-ph] 19 Feb 2013 quantum memory, whereas the electron spin, which has a short coherence time, but interacts strongly with external fields, serves as a readout gate 4,7,9 . In this architecture, the permanent presence of the electron spin is a source of decoherence to the nuclear spin 8 . To avoid such electron spin induced decoherence, the electron that carries the spin should be physically removed when it is not needed and returned to the nuclear spin only when the initialization or readout gate is applied. One approach to address this problem is to frequently remove the electron, e.g. by photo-ionization with a strong laser, resulting in a motional narrowing type of decoupling 9 . Another approach -that is followed in this workis to choose an electronic system with a spin-free ground state and a meta-stable excited spin state that can be optically pumped and activated prior to the application of the readout gate 8 . Such a system implemented with a single solid state defect would enable a universal nuclear spin gate. In the following we present a suitable defect in diamond and demonstrate coherent control of a single nuclear spin in the spin-free electronic ground state. Notably, besides the NV center, this is the second known single spin defect in the solid state, whose coherent spin motion is detectable at room temperature....

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Low-power multipulse line narrowing in solid-state NMR

Cited by 153 publications

References 23 publications

Coherence time of decoupled nuclear spins in silicon

Coherence time of decoupled nuclear spins in silicon

Robust dynamical decoupling

Readout and control of a single nuclear spin with a metastable electron spin ancilla

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