Robust dynamical decoupling for arbitrary quantum states of a single NV center in diamond

Shim, Jae-Hyeok; Niemeyer, I.; Zhang, J.; Suter, Dieter

doi:10.1209/0295-5075/99/40004

Cited by 31 publications

(29 citation statements)

References 26 publications

(59 reference statements)

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“…However, these sequences are very sensitive to flip angle errors due to imperfect pulse lengths [40]. We observe that after hundred XY-4 pulses our measurements become unusable.…”

Section: Slmentioning

confidence: 89%

Locking of electron spin coherence above 20 ms in natural silicon carbide

et al. 2017

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We demonstrate that silicon carbide (SiC) with natural isotope abundance can preserve a coherent spin superposition in silicon vacancies over unexpectedly long time approaching 0.1 seconds. The spin-locked subspace with drastically reduced decoherence rate is attained through the suppression of heteronuclear spin cross-talking by applying a moderate magnetic field in combination with dynamic decoupling from the nuclear spin baths. We identify several phonon-assisted mechanisms of spin-lattice relaxation, ultimately limiting quantum coherence, and find that it can be extremely long at cryogenic temperature, equal or even longer than 8 seconds. Our approach may be extended to other polyatomic compounds and open a path towards improved qubit memory for wafer-scale quantum techmologies.PACS numbers: 76.30. Mi, 42.50.Dv, 76.70.Hb Introduction -Long electron quantum coherence in solid-state systems is the ultimate prerequisite for new technologies based on quantum phenomena [1,2]. Particularly, the sensitivity of quantum sensors scales with the electron spin coherence time T 2 [3,4]. One of the common sources of decoherence is the interaction with fluctuating nuclear spins, and the usual way to prolong spin coherence is to perform isotope purification of the crystal. Indeed, the longest electron T 2 times of about 1 s and 0.6 s have been reported for spin-free silicon 28 Si and diamond 12 C crystals, respectively [5,6]. However, isotope purification is a technologically demanding procedure, which is not always possible. Therefore, one of the key challenges in quantum information science is to achieve long-lived spin coherence in natural materials.To address this goal, we combine two approaches. First, we exploit the suppression of mutual spin flip-flop processes between different types of nuclei in binary compounds, which occur in strong enough magnetic fields according to the theoretical simulations of Ref. [7]. Second, we use a periodic train of radiofrequency (RF) pulses to refocus spin coherence and decouple electron spins from inhomogeneous environment, similar to that applied for color centers [6] and quantum dots (QDs) [8].In recent years, SiC is attracting continuously growing interest as a technologically perspective platform for quantum spintronics [9][10][11][12][13][14][15][16][17] with the ability for single spin engineering and control [18][19][20][21]. The longest T 2 in SiC reported to date is 1 ms at cryogenic temperature [19]. We observe that in a finite magnetic field, a coherent spin superposition can be locked over longer time, which continuously increases up to about 75 ms with the number of decoupling pulses. The absence of saturation indicates that the longest possible spin locking time T

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“…However, these sequences are very sensitive to flip angle errors due to imperfect pulse lengths [40]. We observe that after hundred XY-4 pulses our measurements become unusable.…”

Section: Slmentioning

confidence: 89%

Locking of electron spin coherence above 20 ms in natural silicon carbide

et al. 2017

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“…Furthermore, the ability of the concatenated XY8 sequence to increase the NV ensemble spin coherence times is better than the KDD sequence. Using the concatenated XY8 protocol, we extended the coherence time of the arbitrary spin state of an ensemble of ∼ 10 4 NV centers from ∼ 0.7 ms up to ∼ 30 ms. Our work sheds new light on the robustness of DD protocols for long coherence times and large numbers of pulses, compared to previous works on single NV centers, 14,27 for which a contrast drop with the number of pulses was not observed, and concatenation did not improve the robustness against pulse errors. In this work, however, for coherence times of ∼ 30 ms and thousands of applied pulses, we show that concatenation can form a useful tool for overcoming the accumulation of pulse errors.…”

Section: Discussionmentioning

confidence: 49%

“…NV spin coherence times on the order of milliseconds have been achieved in single NV centers at room temperature, either through careful engineering of a low spin impurity environment during diamond synthesis 11 or through application of pulsed [12][13][14][15] and continuous 16,17 dynamical decoupling (DD) microwave (MW) pulse sequences. Such single NV spin coherence times have been used to demonstrate very sensitive magnetic 1-10 and electric 18 measurements, as well as high-fidelity quantum operations.…”

Section: Introductionmentioning

confidence: 99%

“…[25][26][27] The preservation of arbitrary NV spin states has been previously considered at room temperature and for single NV centers. [12][13][14] In this work, we perform a theoretical and experimental analysis of several DD protocols, including standard CPMG and XY-based pulse sequences as well as modifications thereon, to extract an optimizal protocol for NV ensembles at a temperature of 77 K. We increase the coherence time of an arbitrary NV ensemble state from ∼ 0.7 ms (a single Hahn-echo measurement) up to ∼ 30 ms, which is more than an order of magnitude improvement. Similar DD protocol optimizations have been performed in the past for phosphorus donors in silicon 26 and single NV centers.…”

Section: Introductionmentioning

confidence: 99%

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Improving the coherence properties of solid-state spin ensembles via optimized dynamical decoupling

et al. 2016

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In this work, we optimize a dynamical decoupling (DD) protocol to improve the spin coherence properties of a dense ensemble of nitrogen-vacancy (NV) centers in diamond. Using liquid nitrogen-based cooling and DD microwave pulses, we increase the transverse coherence time T 2 from ∼ 0.7 ms up to ∼ 30 ms. We extend previous work of single-axis (Carr-Purcell-Meiboom-Gill) DD towards the preservation of arbitrary spin states. After performing a detailed analysis of pulse and detuning errors, we compare the performance of various DD protocols. We identify that the concatenated XY8 pulse sequences serves as the optimal control scheme for preserving an arbitrary spin state. Finally, we use the concatenated sequences to demonstrate an immediate improvement of the AC magnetic sensitivity up to a factor of two at 250 kHz. For future work, similar protocols may be used to increase coherence times up to NV-NV interaction time scales, a major step toward the creation of quantum collective NV spin states.

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“…Several techniques have been developed for protecting quantum systems against this effect, including passive schemes like decoherence-free subspaces [3] or active techniques like dynamical decoupling (DD) [4][5][6]. So far, these techniques have been applied mostly to the protection of quantum states in quantum memories [7][8][9][10][11][12]. However, similar protection is also required for quantum information processing.…”

mentioning

confidence: 99%

Experimental Protection of Two-Qubit Quantum Gates against Environmental Noise by Dynamical Decoupling

Zhang

Suter

2015

Phys. Rev. Lett.

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Hybrid systems consisting of different types of qubits are promising for building quantum computers if they combine useful properties of their constituent qubits. However, they also pose additional challenges if one type of qubits is more susceptible to environmental noise than the others. Dynamical decoupling can help to protect such systems by reducing the decoherence due to the environmental noise, but the protection must be designed such that it does not interfere with the control fields driving the logical operations. Here, we test such a protection scheme on a quantum register consisting of the electronic and nuclear spins of a nitrogen-vacancy center in diamond. The results show that processing is compatible with protection: The dephasing time was extended almost to the limit given by the longitudinal relaxation time of the electron spin.PACS numbers: 03.67.Pp,03.67.Lx -Introduction. Choosing the most suitable qubit systems and implementing high-precision quantum gate operations on them may be considered as the main challenges for building quantum computers that will be capable of solving certain problems qualitatively faster than classical computers [1,2]. In every physical realization, environmental noise is present, which degrades the information stored in the quantum systems. Several techniques have been developed for protecting quantum systems against this effect, including passive schemes like decoherence-free subspaces [3] or active techniques like dynamical decoupling (DD) [4][5][6]. So far, these techniques have been applied mostly to the protection of quantum states in quantum memories [7][8][9][10][11][12]. However, similar protection is also required for quantum information processing. Here, the protection must be designed in such a way that it decouples the protected system from environmental noise, but not from the control fields that are applied for driving the gate operations. Experimental implementations of protected single-qubit gates and some special 2-qubit gates, such as a controlled-NOT (CNOT) gate, were recently reported [13][14][15][16], but so far no scheme was demonstrated that can be applied to arbitrary twoqubit gates in different physical qubit systems. Implementing quantum computing in hybrid systems is a promising strategy for building quantum computers, as it increases the range of possible systems and allows one to combine useful properties of different types of qubits [17][18][19][20]. As a typical hybrid system, the nitrogen vacancy (NV) center in diamond consists of an electronic spin S = 1 and a nitrogen nuclear spin I = 1 and combines several useful properties for a quantum register. It also poses some challenges, mostly because the characteristic properties of the two types of spins differ by many orders of magnitude. For example, the natural coherence time at room temperature of the electron spin is of the order of 1 µs, while that of the nuclear spin is 5 ms [15]. The electron spin dephasing time is usually shorter than typical durations of gates applied to the nit...

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Robust dynamical decoupling for arbitrary quantum states of a single NV center in diamond

Cited by 31 publications

References 26 publications

Locking of electron spin coherence above 20 ms in natural silicon carbide

Locking of electron spin coherence above 20 ms in natural silicon carbide

Improving the coherence properties of solid-state spin ensembles via optimized dynamical decoupling

Experimental Protection of Two-Qubit Quantum Gates against Environmental Noise by Dynamical Decoupling

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