Preserving electron spin coherence in solids by optimal dynamical decoupling

Du, Jiangfeng; Rong, Xing; Zhao, Nan; Wang, Ya; Yang, Jerry Zhijian; Liu, Ren‐Bao

doi:10.1038/nature08470

Cited by 365 publications

(374 citation statements)

References 30 publications

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“…We show that this spin-bath suppression enhances the efficacy of dynamical decoupling techniques, enabling large values for the multiqubit FOM ~2×10 14 (ms cm − 3 ; compare, for example, to ref. 24, and to the similar FOM obtained with a much higher NV density sample 9 ).…”

supporting

confidence: 79%

Suppression of spin-bath dynamics for improved coherence of multi-spin-qubit systems

et al. 2012

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multi-qubit systems are crucial for the advancement and application of quantum science. such systems require maintaining long coherence times while increasing the number of qubits available for coherent manipulation. For solid-state spin systems, qubit coherence is closely related to fundamental questions of many-body spin dynamics. Here we apply a coherent spectroscopic technique to characterize the dynamics of the composite solid-state spin environment of nitrogen-vacancy colour centres in room temperature diamond. We identify a possible new mechanism in diamond for suppression of electronic spin-bath dynamics in the presence of a nuclear spin bath of sufficient concentration. This suppression enhances the efficacy of dynamical decoupling techniques, resulting in increased coherence times for multispin-qubit systems, thus paving the way for applications in quantum information, sensing and metrology.

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supporting

confidence: 79%

Suppression of spin-bath dynamics for improved coherence of multi-spin-qubit systems

et al. 2012

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“…Relaxation may occur via the transverse and longitudinal relaxation channels characterized by their respective decay times T 2 and T 1 . The transverse dephasing rate G 2 ¼ 1/T 2 is increased by fluctuations at low frequencies (kHz to MHz) and can be monitored using spin echoes or higher order dynamical decoupling microwave control protocols [25][26][27] . The longitudinal relaxation rate G 1 ¼ 1/T 1 describes the population decay of a polarized spin into thermal equilibrium.…”

Section: Nv Relaxometrymentioning

confidence: 99%

Magnetic spin imaging under ambient conditions with sub-cellular resolution

Steinert¹,

Ziem²,

et al. 2013

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The detection of small numbers of magnetic spins is a significant challenge in the life, physical and chemical sciences, especially when room temperature operation is required. Here we show that a proximal nitrogen-vacancy spin ensemble serves as a high precision sensing and imaging array. Monitoring its longitudinal relaxation enables sensing of freely diffusing, unperturbed magnetic ions and molecules in a microfluidic device without applying external magnetic fields. Multiplexed charge-coupled device acquisition and an optimized detection scheme permits direct spin noise imaging of magnetically labelled cellular structures under ambient conditions. Within 20 s we achieve spatial resolutions below 500 nm and experimental sensitivities down to 1,000 statistically polarized spins, of which only 32 ions contribute to a net magnetization. The results mark a major step towards versatile subcellular magnetic imaging and real-time spin sensing under physiological conditions providing a minimally invasive tool to monitor ion channels or haemoglobin trafficking inside live cells.

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“…Theoretical work also predicted much longer coherence times at higher external magnetic fields 13,15 or when using more advanced pulse sequences 16,17 . The classic example is the Carr-Purcell-Meiboom-Gill (CPMG) sequence 1,18 , but several alternatives have recently been developed 19,20 and demonstrated 21,22 . Their performance is expected to improve as more control pulses are added 17 .…”

mentioning

confidence: 99%

Dephasing time of GaAs electron-spin qubits coupled to a nuclear bath exceeding 200 μs

et al. 2010

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Qubits, the quantum mechanical bits required for quantum computing, must retain their quantum states for times long enough to allow the information contained in them to be processed. In many types of electron-spin qubits, the primary source of information loss is decoherence due to the interaction with nuclear spins of the host lattice. For electrons in gate-defined GaAs quantum dots, spin-echo measurements have revealed coherence times of about 1 µs at magnetic fields below 100 mT (refs 1,2). Here, we show that coherence in such devices can survive much longer, and provide a detailed understanding of the measured nuclearspin-induced decoherence. At fields above a few hundred millitesla, the coherence time measured using a singlepulse spin echo is 30 µs. At lower fields, the echo first collapses, but then revives at times determined by the relative Larmor precession of different nuclear species. This behaviour was recently predicted 3,4 , and can, as we show, be quantitatively accounted for by a semiclassical model for the dynamics of electron and nuclear spins. Using a multiple-pulse Carr-Purcell-Meiboom-Gill echo sequence, the decoherence time can be extended to more than 200 µs, an improvement by two orders of magnitude compared with previous measurements 1,2,5 .The promise of quantum-dot spin qubits as a solid-state approach to quantum computing is demonstrated by the successful realization of initialization, control and single-shot readout of electron-spin qubits in GaAs quantum dots using optical 6 , magnetic 7 and fully electrical 8-10 techniques. To further advance spin-based quantum computing, it is vital to mitigate decoherence due to the interaction of the electron spin with the spins of nuclei of the host material. Understanding the dynamics of this system is also of great fundamental interest 11,12 .Through the hyperfine interaction, an electron spin in a GaAs quantum dot is subjected to an effective magnetic field produced by the nuclear spins. Under typical experimental conditions, this so-called 'Overhauser field' has a random magnitude and direction. Typically, measurements of the coherent electron-spin precession involve averaging over many experimental runs, and thus over many Overhauser field configurations. As a result, the coherence signal is suppressed for evolution times τ ∼ > T 2 * ≈ 10 ns (refs 1, 2). However, the nuclear spins evolve much more slowly than the electron spins, so that the Overhauser field is nearly static over sufficiently short time intervals. Therefore, one can partially eliminate the effect of the random nuclear field by flipping the electron spin halfway through an interval of free precession, a procedure known as Hahn echo. The random contributions of the Overhauser field to the electron-spin precession before and after the spin reversal then approximately cancel out. For longer evolution times, the effective field acting on the electron spin generally changes over the precession interval. This change leads to an eventual loss of coherence on a timescale determined ...

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Preserving electron spin coherence in solids by optimal dynamical decoupling

Cited by 365 publications

References 30 publications

Suppression of spin-bath dynamics for improved coherence of multi-spin-qubit systems

Suppression of spin-bath dynamics for improved coherence of multi-spin-qubit systems

Magnetic spin imaging under ambient conditions with sub-cellular resolution

Dephasing time of GaAs electron-spin qubits coupled to a nuclear bath exceeding 200 μs

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