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

Bar‐Gill, Nir; Pham, Linh; Belthangady, Chinmay; Sage, D. Le; Cappellaro, Paola; Maze, J. R.; Lukin, Mikhail D.; Yacoby, Amir; Walsworth, Ronald L.

doi:10.1038/ncomms1856

Cited by 221 publications

(358 citation statements)

References 45 publications

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“…1 B and C) by performing high spectral resolution magnetometry using the electronic spin of the nitrogen vacancy (NV) center in diamond (19) as a nanoscale probe (7,10,20). Using a conventional XY8-6 dynamical decoupling sequence (17,18) to measure the 14 N nuclear spin of the NV center, we obtain a low-resolution signal where the expected sinc-like dip is barely resolved (Fig.…”

Section: Quantum Interpolationmentioning

confidence: 99%

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Quantum interpolation for high-resolution sensing

Ajoy

Liu

Saha

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Recent advances in engineering and control of nanoscale quantum sensors have opened new paradigms in precision metrology. Unfortunately, hardware restrictions often limit the sensor performance. In nanoscale magnetic resonance probes, for instance, finite sampling times greatly limit the achievable sensitivity and spectral resolution. Here we introduce a technique for coherent quantum interpolation that can overcome these problems. Using a quantum sensor associated with the nitrogen vacancy center in diamond, we experimentally demonstrate that quantum interpolation can achieve spectroscopy of classical magnetic fields and individual quantum spins with orders of magnitude finer frequency resolution than conventionally possible. Not only is quantum interpolation an enabling technique to extract structural and chemical information from single biomolecules, but it can be directly applied to other quantum systems for superresolution quantum spectroscopy.quantum sensing | quantum control | nanoscale NMR | NV centers P recision metrology often needs to strike a compromise between signal contrast and resolution, because the hardware apparatus sets limits on the precision and sampling rate at which the data can be acquired. In some cases, classical interpolation techniques have become a standard tool to achieve a significantly higher resolution than the bare recorded data. For instance, the Hubble Space Telescope uses classical digital image processing algorithms like variable pixel linear reconstruction [Drizzle (1)] to construct a supersampled image from multiple low-resolution images captured at slightly different angles. Unfortunately, this classical interpolation method would fail for signals obtained from a quantum sensor, where the information is encoded in its quantum phase (2). Here we introduce a technique, which we call "quantum interpolation," that can recover the intermediary quantum phase, by directly acting on the quantum probe dynamics, and effectively engineer an interpolated Hamiltonian. Crucially, by introducing an optimal interpolation construction, we can exploit otherwise deleterious quantum interferences to achieve high fidelity in the resulting quantum phase signal.Quantum systems, such as trapped ions (3), superconducting qubits (4, 5), and spin defects (6, 7) have been shown to perform as excellent spectrum analyzers and lock-in detectors for both classical and quantum fields (8-10). This sensing technique relies on modulation of the quantum probe during the interferometric detection of an external field. Such a modulation is typically achieved by a periodic sequence of π-pulses that invert the sign of the coupling of the external field to the quantum probe, leading to an effective time-dependent modulation f (t) of the field (11-13). These sequences, more frequently used for dynamical decoupling (14, 15), can be described by sharp bandpass filter functions obtained from the Fourier transform of f (t). This description lies at the basis of their application for precision spectroscopy, as the fil...

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Section: Quantum Interpolationmentioning

confidence: 99%

“…Quantum systems, such as trapped ions (3), superconducting qubits (4,5), and spin defects (6,7) have been shown to perform as excellent spectrum analyzers and lock-in detectors for both classical and quantum fields (8)(9)(10). This sensing technique relies on modulation of the quantum probe during the interferometric detection of an external field.…”

mentioning

confidence: 99%

Quantum interpolation for high-resolution sensing

Ajoy

Liu

Saha

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Extending the π-pulse duration can reveal what limits the hole width and determine τ c for different spin-bath species. Previous experiments have measured NV decoherence in pulsed-microwave experiments to study the P1 and 13 C τ c [22,[24][25][26]. In comparison, investigating τ c with pulsed hole-burning does not require coherent superpositions, which is useful when τ c is longer than the NV T 2 .…”

Section: The Nvmentioning

confidence: 99%

Microwave saturation spectroscopy of nitrogen-vacancy ensembles in diamond

et al. 2014

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Negatively-charged nitrogen-vacancy (NV − ) centers in diamond have generated much recent interest for their use in sensing. The sensitivity improves when the NV ground-state microwave transitions are narrow, but these transitions suffer from inhomogeneous broadening, especially in high-density NV ensembles. To better understand and remove the sources of broadening, we demonstrate room-temperature spectral "hole burning" of the NV ground-state transitions. We find that hole burning removes the broadening caused by magnetic fields from13 C nuclei and demonstrate that it can be used for magnetic-field-insensitive thermometry. The nitrogen-vacancy (NV) color center in diamond is a defect center consisting of a substitutional nitrogen atom adjacent to a missing carbon atom. When negatively charged (NV − ), its ground state has electronic spin 1 (Fig. 1a), and physical parameters such as magnetic field, electric field, and temperature affect the energies of its magnetic sublevels [1][2][3]. One can measure these parameters by employing optically-detected magnetic resonance (ODMR) techniques [4,5], which use microwave (MW) fields resonant with the NV transitions and detect changes in fluorescence in the presence of excitation light. The NV− ground-state sublevels can be optically accessed and have long spin-relaxation times at room temperature [6], making them useful for sensing. When limited by spin-projection noise, the sensitivity is proportional to Γ/N , where Γ is the ODMR linewidth and N is the number of NV centers probed [1,7,8]. In practice, the transitions are inhomogeneously broadened due to differences in the NV local environments, limiting the ensemble sensitivity. Diamond samples with more paramagnetic impurities also have more inhomogeneous broadening, meaning that larger N often comes with larger Γ. Furthermore, NVs with different Larmor frequencies dephase, which is a limitation in some applications. Although refocusing pulse sequences (such as Hahn echo) can restore the coherence, identifying the sources of ODMR linewidth broadening is essential for NV applications and for understanding the underlying diamond spin-bath and crystal-strain physics.In this work we demonstrate novel use of saturation spectroscopy (or "hole-burning") techniques in an NV ensemble. This is motivated by saturation spectroscopy in atoms, where a spectrally-narrow pump laser selects atoms of a particular velocity class by removing them from their initial state, allowing one to recover narrow absorption lines with a probe laser [9].We present two hole-burning schemes. The analytically simpler scheme ("pulsed hole-burning") is depicted in Fig. 1b. This scheme addresses a two-level subsystem (m s = 0 and +1) and uses a modified pulsed-ODMR sequence (similar to that of Ref.[8]). A spectrally-narrow "hole" π-pulse first shelves some NVs into the m s = +1 state, after which a probe π-pulse reads out its effect on the NV population distribution. Figure 1c shows that using this method can yield hole widths significantly narrower than t...

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“…Furthermore, enhanced NV concentrations could lead to strong NV-NV couplings, which together with long coherence times, achieved using a proper dynamical decoupling protocol [13], could pave the way toward the study of many-body dynamics in the NV-NV interaction-dominated regime [10][11][12]. However, nitrogen defects not associated with vacancies (P1 centers) create randomly fluctuating magnetic fields that cause decoherence of the quantum state of the NV ensemble [14,15]. As a result, in most cases it would be beneficial to increase the concentration of NV centers while keeping the nitrogen concentration constant, i.e.…”

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confidence: 99%

Enhanced concentrations of nitrogen-vacancy centers in diamond through TEM irradiation

Farfurnik

Alfasi

Masis

et al. 2017

Applied Physics Letters

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The studies of many-body dynamics of interacting spin ensembles, as well as quantum sensing in solid state systems, are often limited by the need for high spin concentrations, along with efficient decoupling of the spin ensemble from its environment. In particular, for an ensemble of nitrogenvacancy (NV) centers in diamond, high conversion efficiencies between nitrogen (P1) defects and NV centers are essential, while maintaining long coherence times of an NV ensemble. In this work, we study the effect of electron irradiation on the conversion efficiency and the coherence time of various types of diamond samples with different initial nitrogen concentrations. The samples were irradiated using a 200 keV transmission electron microscope (TEM). Our study reveals that the efficiency of NV creation strongly depends on the initial conversion efficiency as well as on the initial nitrogen concentration. The irradiation of the examined samples exhibits an order of magnitude improvement in the NV concentration (up to ∼ 10 11 NV/cm 2 ), without degradation in their coherence times of ∼ 180 µs. We address the potential of this technique toward the study of many-body physics of NV ensembles and the creation of non-classical spin states for quantum sensing. The study of quantum many-body spin physics in realistic solid-state platforms has been a long-standing goal in quantum and condensed-matter physics. In addition to the fundamental understanding of spin dynamics, such research could pave the way toward the demonstration of non-classical spin states, which will be useful for a variety of applications in quantum information and quantum sensing. One of the leading candidates for such studies is the negatively charged nitrogen-vacancy (NV) center in diamond, having unique spin and optical properties, which make it useful for various sensing applications [1][2][3][4][5][6][7][8][9], as well as a resource for quantum information processing and quantum simulation [10][11][12].The current state-of-the-art is limited by the requirement of obtaining high spin concentrations while maintaining long coherence times. The sensitivity of magnetic sensing grows as the square-root of the number of spins [1,3], thus enhanced NV concentrations could improve magnetometric sensitivities. Furthermore, enhanced NV concentrations could lead to strong NV-NV couplings, which together with long coherence times, achieved using a proper dynamical decoupling protocol [13], could pave the way toward the study of many-body dynamics in the NV-NV interaction-dominated regime [10][11][12]. However, nitrogen defects not associated with vacancies (P1 centers) create randomly fluctuating magnetic fields that cause decoherence of the quantum state of the NV ensemble [14,15]. As a result, in most cases it would be beneficial to increase the concentration of NV centers while keeping the nitrogen concentration constant, i.e. improve the N to NV conversion efficiency.A common technique for improving the conversion efficiency is the irradiation of the sample with elec...

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

Cited by 221 publications

References 45 publications

Quantum interpolation for high-resolution sensing

Quantum interpolation for high-resolution sensing

Microwave saturation spectroscopy of nitrogen-vacancy ensembles in diamond

Enhanced concentrations of nitrogen-vacancy centers in diamond through TEM irradiation

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