Abstract
The ability to shape photon emission facilitates strong photonmediated interactions between disparate physical systems, thereby enabling applications in quantum information processing, simulation and communication. Spectral control in solid state platforms such as color centers, rare earth ions, and quantum dots is particularly attractive for realizing such applications onchip. Here we propose the use of frequencymodulated optical transitions for spectral engineering of single photon emission. Using a scatteringmatrix formalism, we find that a twolevel system, when modulated faster than its optical lifetime, can be treated as a singlephoton source with a widely reconfigurable photon spectrum that is amenable to standard numerical optimization techniques. To enable the experimental demonstration of this spectral control scheme, we investigate the Stark tuning properties of the silicon vacancy in silicon carbide, a color center with promise for optical quantum information processing technologies. We find that the silicon vacancy possesses excellent spectral stability and tuning characteristics, allowing us to probe its fast modulation regime, observe the theoreticallypredicted twophoton correlations, and demonstrate spectral engineering. Our results suggest that frequency modulation is a powerful technique for the generation of new light states with unprecedented control over the spectral and temporal properties of single photons.
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Introduction
Photonmediated interactions between quantum systems are at the heart of a number of quantum information applications including quantum networking, simulation, and computation^{1,2,3,4,5,6,7}. Because the physical characteristics of nodes can differ drastically, the ability to spectrally control photon emission enables networks composed of disparate physical systems. Spectralshaping techniques can enable the scaling of quantum simulators despite the inhomogeneities in the comprising qubits^{8,9}. Spectral shaping is also necessary to maximize the absorption fidelity of a photon by an atom^{10}, and to maximize photonphoton interference visibility in the presence of imperfections^{11}. Moreover, frequencyencoded quantum states can be used for highdimensional entanglement protocols^{12,13}.
The prevalent approach for the deterministic generation of single photons is spontaneous emission from a twolevel system (TLS)^{14}. However, since unperturbed spontaneous emission only produces photons with a Lorentzian spectrum, significant effort has been devoted to exploring more complex systems for spectral control of singlephoton emission. For instance, a TLS with a timedependent coupling to a cavity has been studied for symmetrization of singlephoton wavepackets^{15,16}, and cascaded threelevel systems and lambda systems have been used for partlystimulated twophoton emission^{17} and Raman emission^{18,19}, respectively. A systemagnostic approach to photon shaping is postprocessing emitted photons using cavities^{20}, electrooptic phase modulators^{21}, and nonlinear frequency conversion^{22,23}, at the expense of additional system complexity and loss.
In this article, we propose a comprehensive alternative to these techniques that requires only a TLS whose transition energy can be rapidly modulated. The timemodulated TLS has been studied in other contexts since the early days of quantum mechanics^{24}; its application in atomic systems^{25}, superconducting qubits^{26}, gatedefined quantum dots^{27}, and solidstate defects^{28,29,30,31,32} has allowed for the demonstration of fundamental phenomena such as spectral sideband formation, LandauZenerStückelberg interference, and motional averaging. Here, we examine the fast timemodulated TLS as a singlephoton source. To this end, we study the fewphoton scattering properties of the modulated TLS, as well as its singlephotonemission fidelity under pulsed resonant drive. We find that, remarkably, in the fast modulation regime (i.e., modulation faster than the optical lifetime) the modulated TLS can be treated like a conventional twolevel system but with an exotic, reconfigurable spectrum. We experimentally characterize static and timemodulated Stark shift in the negativelycharged single silicon vacancy (V\({}_{\,\text{Si}\,}^{}\)) color centers in 4H silicon carbide (4HSiC), and observe that the optical coherence properties of the V\({}_{\,\text{Si}\,}^{}\) are preserved even under highamplitude modulation. With this system, we investigate the fewphoton scattering from a modulated quantum emitter, and demonstrate the proposed spectral engineering of single photons from a solidstate TLS. Finally, we demonstrate pulsed optical orbital control under modulation through measurement of Rabi oscillations and Ramsey interference.
Results
Continuouswave scattering off a modulated twolevel system
We study the modulated TLS via the quantum optics formalism of Markovian open quantum systems, with the goal of understanding the fewphoton statistics and the singlephoton spectra of scattered photons. We consider a modulated TLS driven by an arbitrary periodic modulation Δ(t) with period 2π/Ω,
where ω_{0} is the resonant frequency of the TLS and σ is the deexcitation operator. Furthermore, we impose a decay rate γ corresponding to the system lifetime. The Floquet eigenstates for this Hamiltonian can be computed analytically (see Supplementary Note 4). To study the form of the emitted photon wavepacket under excitation by a weak coherent state, we use single and twophoton scattering matrices of the modulated TLS. While scattering matrices are traditionally computed only for timeindependent systems, it was recently shown that they can be defined and computed for timedependent systems^{33,34}. As is shown in Supplementary Note 3, the singlephoton scattering matrix through the modulated TLS S(ω, ν), defined as the amplitude of producing an output photon at frequency ω when the system is excited with an input photon at frequency ν, can be expressed as:
where γ_{i,o} is the coupling rate into the input (output) channel, γ = γ_{i} + γ_{o} is the total decay rate of the twolevel system, and α_{m} is the Fourierseries coefficient of the phase \(\exp ({\rm{i}}\mathop{\int}\nolimits_{0}^{t}\Delta (t^{\prime} )dt^{\prime} )\) accumulated by the excited state of the modulated TLS up to time t, corresponding to the harmonic \(\exp ({\rm{i}}m\Omega t)\). We note that the form of S(ω, ν) implies that the output photon state corresponding to an input photon state at frequency ν has frequencies \(\nu +p\Omega ,\,p\in {\mathbb{Z}}\) as a consequence of the periodic modulation of the emitter frequency (see Fig. 1a). In particular, a narrowband incident photon wavepacket would scatter from the modulated twolevel system into different modulation sidebands (Fig. 1b). In the slow modulation regime (Ω_{0} ≪ γ), the total transmission from the TLS (T(ν)), computed as a sum of transmission into individual sidebands (∣S_{p}(ν)∣^{2}), is simply a timeaverage of transmission spectra with different resonant frequencies. The fast modulation regime (Ω_{0} ≫ γ) is characterized by distinctive sidebands with high transmission at the resonant frequency (see Fig. 1c). The scattering amplitudes into different sidebands can be controlled by an appropriate choice of the timedependent frequency modulation Δ(t).
For nonclassical light generation, especially singlephoton generation, it is of utmost importance to understand the statistics of photons transmitted through the modulated TLS. In this context, of particular interest is the scattering of a monochromatic twophoton pair at frequency ν from the modulated TLS. The output state \(\left{\psi }_{\text{out}}(\nu )\right\rangle\) can be described by its wavefunction ψ_{out}(t, t + τ; ν), which represents the amplitude of one photon in the output being emitted at time t and the second photon being emitted after a delay of τ. A detailed calculation of ψ_{out}(t, t + τ; ν) in terms of the modulation Δ(t) within the framework of the scattering theory is outlined in Supplementary Note 3. Figure 1d shows G(t, τ; ω_{0}) = ∣ψ_{out}(t, t + τ; ω_{0})∣^{2} under different modulation regimes; in all cases, it can be seen that G(t, 0; ν) = 0. This implies that any modulated TLS shows perfect photon antibunching. In the slow modulation regime, the amplitude of the twophoton wavepacket varies periodically with the delay τ as a consequence of the periodic drive. In the fast modulation regime, a continuouswave excitation only significantly addresses one of the Floquet sidebands and consequently, the timedomain scattering properties resemble those of an unmodulated TLS. Fig. 1e shows the twophoton correlation function \({g}^{(2)}(\tau ;{\omega }_{0})={\langle G(t,\tau ;{\omega }_{0})\rangle }_{t}/{T}^{2}({\omega }_{0})\). As with G(t, τ; ω_{0}), we observe that g^{(2)}(τ; ω_{0}) oscillates with τ in the slow modulation regime, and resembles the correlation function of an unmodulated TLS in the fast modulation regime.
Using a scattering matrix formalism, we have found that in the limit of fast drive a modulated TLS behaves very much like a conventional singlephoton source but with a controllable spectrum determined by the form of the drive Δ(t). Thus, a modulated TLS can serve as a source of photons whose spectral composition is amenable to standard numerical optimization techniques; one can optimize Δ(t) given a target singlephoton spectrum. Figure 2 shows examples of singlephoton spectra that can be obtained via such optimization (see Methods). We note that due to the periodicity of Δ(t), this approach is limited to producing photons with discrete, comblike spectra. This restriction is lifted for aperiodic Δ(t), which we discuss further in Supplementary Notes 4 and 8.
Reconfiguring photon spectra using optimized periodic modulation
To realize the proposal experimentally, it is essential to identify a singlephoton source amenable to fast, broadband modulation. A suitable solidstate defect must possess a widely tunable optical transition while displaying minimal spectral diffusion in a stationary state and under rapid modulation. Here, we study the Stark tuning and the spectral stability of a single V\({}_{\,\text{Si}\,}^{}\) color center in 4HSiC (abbreviated V_{Si} henceforth), and find the V_{Si} to satisfy these requirements. The V_{Si} is a color center with promise for quantum information processing technologies due to its long spin coherence time^{35}, unique 3/2 spin system^{36,37}, and compatibility with scalable photonic architectures^{38}. The V_{Si} spectrum comprises two optical transitions, which are separated by 1 GHz via spinspin coupling (corresponding to spin ±1/2 and ±3/2 sublevels). The V_{Si} occurs at two inequivalent lattice sites in the 4HSiC lattice, denoted by h and k, with the zerophonon lines at 861 and 916 nm, respectively. The properties of the defects are largely similar^{39,40}; one distinction is that the optical coherence of kV_{Si} is more robust against dephasing caused by acoustic phonons (characterized by narrower linewidths at elevated temperatures)^{41}.
We first probe the static Stark shift of the V_{Si} by applying a voltage across gold electrodes fabricated on the acut surface of 4HSiC, oriented to apply the field along the axis of symmetry of the defect (see Supplementary Note 1), and measure the singledefect spectrum (see Methods). All measurements are performed at 5 K via resonant absorption spectroscopy, i.e., photoluminescence excitation (PLE). As shown in Fig. 3a, we observe that the zerophonon line of the V_{Si} can be tuned by 200 GHz without degradation of spectral properties: in other solidstate emitters, the degradation manifests as blinking, charge conversion, or carrier tunneling^{42,43} The V_{Si} does require the periodic application of an aboveresonant laser for charge stabilization^{39,40}, but we do not observe an increased rate of charge conversion with the application of a bias voltage. The static Stark shift measurement is performed by incrementing the applied voltage in steps of 0.5 V and sweeping a tunable laser, programmed to track the frequency of the V_{Si} as it shifts. From electrostatic simulation of the electrodes and the Lorentz local field approximation^{44}, we calculate the local electric field strength at the V_{Si} location (assuming the defect position is accurate within 1 μm^{3}), and deduce a strong Stark shift of 3.65 ± 0.09 GHz/(MV/m). This corresponds to an electric dipole moment of 0.72 ± 0.02 Debye, in disagreement with the theoretical prediction of 0.2 Debye^{45}. We note that a recent experimental study in V_{Si} ensembles estimated the dipole moment to be 0.18 Debye^{46}. Nevertheless, the widerange, highresolution characterization of the Stark shift of single color centers presented in this work gives us confidence in the dipole moment magnitude we report. A further investigation of spectral diffusion properties and Stark shift for k and hV_{Si} is presented in the Supplementary Note 2.
We then proceed to characterize the V_{Si} under Stark modulation, in order to observe spectra of Floquet eigenstates which have been previously seen in other solid state quantum emitters such as the NV and SiV centers in diamond^{31,47}, the divacancy in SiC^{30}, and quantum dots^{28}. Applying sinusoidal modulation Δ(t) for a range of frequencies and amplitudes, we observe that the V_{Si} spectrum matches the prediction of the scattering matrix theory (Fig. 3b). Crucially, we see that the V_{Si} spectral stability is not impacted by the periodic drive. A detailed analysis of the spectral stability of the V_{Si} under modulation is presented in the Supplementary Note 2. We then study the twophoton scattering properties of the V_{Si}. As expected for a singlephoton emitter, we observe antibunching for all modulation frequencies (Fig. 3c). Additionally, we observe two independent effects: (1) the oscillations in g^{(2)}(τ) due to the emitter modulation, present for all τ; and (2) a modulationindependent signature of interference between the four ground states in the ground manifold, decaying exponentially with τ due to the spin mixing via the intersystem crossing. A detailed analysis of this interference effect is presented in the Supplementary Note 5. The 15 MHz, 150 MHz, and 1.5 GHz modulation frequencies probe the slow, intermediate, and fast regimes, respectively. In the slow regime, the shape of g^{(2)}(τ) is strongly modified by the Stark modulation. As the modulation frequency is increased, the g^{(2)}(τ) becomes practically indistinguishable from that of the unmodulated emitter, in agreement with the scatteringmatrix theory.
To generate spectrallyengineered Floquet states, we drive the V_{Si} periodically with optimized harmonics. To demonstrate the range of achievable spectra, we prepare the V_{Si} in Floquet states that emit photons in an equal superposition of two and four colors. We restrict the optimization to a bandwidth of 6 GHz, limited by the external microwave losses. Figure 4a, c shows the theoretical spectrum resulting from the optimization of a two (four) color photon spectrum. The corresponding microwave drives Δ(t) are shown in the Fig. 4b, d insets, and more detail is given in Supplementary Note 4. The experimentallygenerated two (four) color state is shown in Fig. 4b, d. We note that the PLE measurement is performed in the weakexcitation regime, and thus probes the spectral composition of the photons spontaneously emitted by the system^{48}.
We have thus far considered a modulated TLS under continuouswave optical excitation. However, it is also important to understand the behavior of the modulated TLS under pulsed optical excitation; this would determine whether a modulated emitter could be used as a deterministic source of shaped single photons. In a traditional TLS singlephoton source, ondemand generation of highlyindistinguishable photons relies on coherent excitation with a short πpulse, which prepares the system in the excited state with high fidelity, thus generating very nearly oneandonlyone photon per excitation^{49}. The πpulse must be resonant with the TLS, as a detuned pulse would induce offresonant Rabi oscillations, which cannot efficiently transfer population.
To determine the feasibility of highfidelity singlephoton generation from a modulated quantum emitter, we investigate numerically the behavior of the modulated V_{Si} under pulsed optical drive using experimental parameters corresponding to the highamplitude modulation in Supplementary Fig. 7. We model the excited state population dynamics upon excitation with a short Gaussian optical pulse centered on one of the sidebands (Fig. 5a). We find that, unsurprisingly, the population dynamics are strongly dependent upon the phase of the periodic modulation Δ(t) relative to the arrival time of the optical pulse, as shown in Fig. 5b. Clearly, the simple πpulse prescription used in an unmodulated TLS for complete population transfer from the ground to the excited state does not apply. Instead, the phase and the pulse area are two free parameters that determine the singlephoton generation fidelity (incidentally, both can be precisely controlled in experiment). For a range of experimentallyrelevant pulse widths, we search the twoparameter space to compare the optimal singlephoton generation fidelity of a modulated TLS to that of the unmodulated TLS: we evaluate the pulsewise twophoton correlation function g^{(2)}[0] as well as the expected number of emitted photons per pulse. Crucially, we find that the singlephoton generation fidelity for a modulated TLS is very similar to that of the timeindependent TLS^{50}, reinforcing the potential utility of the modulated TLS as a deterministic singlephoton source.
We proceed to investigate the interaction of a modulated V_{Si} with short optical pulses. Using a resonant pulsed laser, we demonstrate fast control of the unmodulated V_{Si} orbital state (Fig. 6a). The high density of V_{Si} in the sample induces a background fluorescence that limits the signal contrast. As the pulse bandwidth (3 ps^{−1}) far exceeds the V_{Si} modulation amplitude, modulationinduced orbital dynamics (shown in Fig. 5b) cannot be resolved with a single pulse. In order to observe signatures of Stark modulation in the orbital trajectories of the V_{Si}, we perform a Ramsey interference experiment, where the V_{Si} is manipulated by a pair of 3 ps optical π/2 pulses separated by 200 ps (Fig. 6b). We observe a strong dependence of the Ramsey interference amplitude on the modulation frequency (Fig. 6c). This effect is a consequence of the timedependent Larmor precession experienced by the modulated V_{Si} on the equator of the Bloch sphere. When the pulse delay is not a multiple of the modulation period, the accumulated interpulse precession depends on the phase of the microwave signal relative to the arrival of the first pulse. As we show in Supplementary Note 6, the timeaveraged Ramsey interference pattern is described by \(1/2+1/2\cos (\omega {t}_{{\mathrm{delay}}}){J}_{0}\left(\right.2\frac{A}{\Omega }\sin (\frac{\Omega {t}_{{\mathrm{delay}}}}{2})\left)\right.\), where t_{delay} is the time delay between the two π/2 pulses. We measure the Ramsey interference across different modulation frequencies and observe the recovery of the full Ramsey contrast at 5 and 10 GHz, in excellent agreement with the theoretical prediction (Fig. 6d).
Discussion
In this article, we have proposed and demonstrated spectral optimization of a quantum emitter and showed that a simple modulated twolevel system can be used as a spectrally reconfigurable deterministic singlephoton source. Using a scattering matrix formalism, we develop a rigorous model of this system and use the model to engineer unconventional photon states. Using color centers modulated via the Stark shift, we experimentally demonstrate spectral shaping and study the interaction of a modulated optical transition with fast optical pulses.
In light of the recent technological advances in SiC photonics^{51,52}, including the recent integration of single V_{Si} into nanophotonic architectures^{38}, our results suggest that the V_{Si} is an excellent candidate for a scalable spectrally reconfigurable singlephoton source. Furthermore, as this approach to spectral control of singlephoton emission requires only a rapidly modulated optical transition, it should be applicable to other solidstate defects modulated either via the Stark effect^{30,53,54} or acoustically^{28,47}.
As discussed in Supplementary Note 8, the ability to rapidly chirp the emitter frequency enables the generation of spectrallyengineered chirped photons amenable to extreme temporal compression with additional dispersion correction. Moreover, coherencepreserving rapid spectral modulation of an optical transition may have applications beyond spectral shaping. In atomic and superconducting qubit systems, frequency modulation has been proposed for simulating topological phase transitions^{24}, overcoming dephasing^{26}, and implementing quantum gates using resolved sidebands^{55}. TLS modulation based on the Stark effect is a flexible technique, compatible with integrated nanophotonic cavity systems which enhance atomphoton interactions^{56,57}. Cavity integration would enable a solidstate implementation of the fast timemodulated Jaynes–Cummings system, which has received extensive theoretical investigation^{58,59}. In spinbased solidstate systems, where inhomogeneous broadening plagues the indistinguishability of photons emitted from different quantum nodes, optical transitions that are widely tunable both statically and dynamically can open pathways toward scalable integrated quantum photonic systems. A unique application of highfidelity fast control (which we explore numerically in Supplementary Note 8) is the dynamic compensation of inhomogeneous broadening of an emitter ensemble via a single optimized microwave signal. In contrast with the traditional approach of statically tuning N emitters on resonance using N − 1 electrodes, this method requires just one set of electrodes and does not require spatiallyseparated emitters, making it uniquely suitable to improve photonmediated spinspin interactions in lowmodevolume nanophotonic cavities^{57}.
Methods
Floquet spectrum optimization
When the emitter linewidth is much smaller than the modulation period, which is the case for our optimizations, the shape of the spectrum is dictated solely by the Fourier components of \(\exp (i\mathop{\int}\nolimits_{0}^{t}\Delta (t^{\prime} )dt^{\prime} )\). Thus, we can define our desired Fourier series decomposition of our Floquet state and optimize the Fourier components of \(\exp (i\mathop{\int}\nolimits_{0}^{t}\Delta (t^{\prime} )dt^{\prime} )\) to match those of the desired state. To do this we use the BroydenFletcherGoldfarbShanno (BFGS) algorithm. Our optimization parameters are the real and imaginary parts of all Fourier series components of Δ(t) within the defined bandwidth, and our cost function is the mean squared error of the Fourier series components calculated with the discrete Fourier transform. By scaling the amplitude of Δ(t) by the modulation frequency Ω, the spectral shape is conserved.
Sample preparation
The experiments were performed using a 100μ mthick 4H^{28}Si^{12}C epilayer grown by chemical vapour deposition on a ntype (0001) 4HSiC substrate. Color centers are generated via electron irradiation. In order to investigate whether the spectral stability of the V_{Si} is influenced by the electron irradiation energy, one sample was irradiated with an average energy of 2 MeV (at QST, Japan) and another at an average energy of 23 MeV (at Stanford SLAC, USA), with a dose of 1 × 10^{13} cm^{−2} and 5 × 10^{12} cm^{−2}, respectively. Samples were annealed for 30 min at 300 °C after irradiation. Samples were diced and their edges were polished (DAG 810 from Disco Corp.). Then, 3 μm were removed from the surface with reactive ion etching (using SF_{6}), to minimize the presence of defects that arise from mechanical processing. Gold electrodes were patterned on the sample edge via ebeam lithography and liftoff. No difference in the properties of single V_{Si} was observed between the two samples; however, as expected, the higherenergy irradiation produced a greater fraction of opticallyactive defects of unknown origin.
Experimental setup
The measurements are performed in a closedcycle cryostat (Montana Instruments) at a temperature of 5 K. The sample is mounted onto a custombuilt circuit board with a microwave stripline optimized for highfrequency operation. The signal is delivered onto the sample with aluminum wirebonds. The cutoff frequency of the microwave setup was measured to be 10.5 GHz. Optical spectra of the V_{Si} are measured via the PLE technique: by scanning a weak resonant laser (power at the objective lens ranging between 50 and 150 nW) across the transition, and detecting only the emission into the phonon sideband via a tunable longpass filter (Semrock). Twophoton coincidences are recorded with timing electronics with a 10 ps resolution (Swabian Instruments). To control the charge state of the emitter, a 1μs aboveresonant (740 nm) repump pulse is applied at a 1kHz repetition rate. For pulsed measurements, a picosecond Ti:Sapphire laser (Spectra Physics) with a homebuilt pulse delay stage and EOMbased pulse picker are used. For DC Stark tuning characterization, voltage is applied to the gold electrodes via a programmable voltage source (Keithley). Singlefrequency microwave drive is delivered via a continuouswave signal generator with 3.3 GHz bandwidth (RhodeShwartz). Engineered multifrequency microwave drives are generated by an arbitrary waveform generator (Keysight) with amplification (MiniCircuits). A diagram of the optical and electronic experimental setup is shown in Supplementary Figs. 1 and 2.
Data availability
All data relevant to the current study are available from the corresponding author on request.
Code availability
The code used for scattering matrix simulations can be accessed at https://github.com/rahultrivedi1995/oqs_scattering
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Acknowledgements
This research is funded in part by the U.S. Department of Energy, Office of Science, under Awards DESC0019174 and DEAc0276SF00515; and the National Science Foundation under award 1839056. Part of this work was performed at the Stanford Nanofabrication Facility (SNF) and the Stanford Nano Shared Facilities (SNSF), supported by the National Science Foundation under award ECCS1542152. D.L. acknowledges support from the Fong Stanford Graduate Fellowship (SGF) and the National Defense Science and Engineering Graduate Fellowship. A.D.W. acknowledges support from the Herb and Jane Dwight SGF. M.A.G. acknowledges support from the Albion Hewlett SGF and the NSF Graduate Research Fellowship. R.T. acknowledges funding from Kailath Graduate Fellowship. N.T.S. acknowledges funding by the Swedish Research Council (Vetenskapsradet VR 201604068). J.U.H. acknowledges funding by the Swedish Energy Agency (436111). N.T.S. and J.U.H. acknowledge funding by the EU H2020 project QuanTELCO (862721) and the Knut and Alice Wallenberg Foundation (KAW 2018.0071). T.O. acknowledges support from grants JSPS KAKENHI 17H01056 and 18H03770. J.W. acknowledges support by the European Research Council (ERC) grant SMel, the European Commission Marie Curie ETN “QuSCo” (GA No 765267), the Max Planck Society, the Humboldt Foundation, the German Science Foundation (SPP 1601), and the EUFET Flagship on Quantum Technologies through the project ASTERIQS. J.W. and F.K. acknowledge the EUFET Flagship on Quantum Technologies through the project QIA. C.D. acknowledges support from the Andreas Bechtolsheim SGF and the Microsoft Research PhD Fellowship.
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D.M.L, A.D.W., M.A.G., J.V. conceived the experiment. M.A.G., D.M.L., A.D.W. built the experimental setup. D.M.L., A.D.W., M.A.G. conducted the experiment. R.T., A.D.W., D.M.L., O.O.S. conducted the theoretical analysis. A.D.W., R.T. performed microwave engineering optimization. N.M., C.B., C.D., F.K., J.W. assisted with experimental setup and material characterization. J.U.H., N.T.S. designed and performed SiC growth. T.O., P.K.V., M.H.N., E.A.N. performed the electron irradiation. S.S., J.P.W.M. provided experimental and theoretical guidance. J.V. supervised the project. D.M.L. and A.D.W. contributed equally to this work. All authors discussed the results and contributed to the final version of the paper.
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Lukin, D.M., White, A.D., Trivedi, R. et al. Spectrally reconfigurable quantum emitters enabled by optimized fast modulation. npj Quantum Inf 6, 80 (2020). https://doi.org/10.1038/s41534020003100
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DOI: https://doi.org/10.1038/s41534020003100
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