Efficient collection of the broadband fluorescence from the diamond nitrogen vacancy (NV) center is essential for a range of applications in sensing, on-demand single photon generation, and quantum ...information processing. Here, we introduce a circular “bullseye” diamond grating which enables a collected photon rate of (2.7 ± 0.09) × 106 counts per second from a single NV with a spin coherence time of 1.7 ± 0.1 ms. Back-focal-plane studies indicate efficient redistribution of the NV photoluminescence into low-NA modes by the bullseye grating.
A central aim of quantum information processing is the efficient entanglement of multiple stationary quantum memories via photons. Among solid-state systems, the nitrogen-vacancy centre in diamond ...has emerged as an excellent optically addressable memory with second-scale electron spin coherence times. Recently, quantum entanglement and teleportation have been shown between two nitrogen-vacancy memories, but scaling to larger networks requires more efficient spin-photon interfaces such as optical resonators. Here we report such nitrogen-vacancy-nanocavity systems in the strong Purcell regime with optical quality factors approaching 10,000 and electron spin coherence times exceeding 200 μs using a silicon hard-mask fabrication process. This spin-photon interface is integrated with on-chip microwave striplines for coherent spin control, providing an efficient quantum memory for quantum networks.
The nitrogen-vacancy (NV) center in diamond exhibits spin-dependent fluorescence and long spin coherence times under ambient conditions, enabling applications in quantum information processing and ...sensing. NV centers near the surface can have strong interactions with external materials and spins, enabling new forms of nanoscale spectroscopy. However, NV spin coherence degrades within 100 nm of the surface, suggesting that diamond surfaces are plagued with ubiquitous defects. Prior work on characterizing near-surface noise has primarily relied on using NV centers themselves as probes; while this has the advantage of exquisite sensitivity, it provides only indirect information about the origin of the noise. Here we demonstrate that surface spectroscopy methods and single-spin measurements can be used as complementary diagnostics to understand sources of noise. We find that surface morphology is crucial for realizing reproducible chemical termination, and use this insight to achieve a highly ordered, oxygen-terminated surface with suppressed noise. We observe NV centers within 10 nm of the surface with coherence times extended by an order of magnitude.
We demonstrate a photonic circuit with integrated long-lived quantum memories. Precharacterized quantum nodes—diamond microwaveguides containing single, stable, negatively charged nitrogen-vacancy ...centers—are deterministically integrated into low-loss silicon nitride waveguides. These quantum nodes efficiently couple into the single-mode waveguides with >1Mcps collected into the waveguide, have narrow single-scan linewidths below 400 MHz, and exhibit long electron spin coherence times up to 120μs . Our system facilitates the assembly of multiple quantum nodes with preselected properties into a photonic integrated circuit with near unity yield, paving the way towards the scalable fabrication of quantum information processors.
Neutral silicon vacancy (SiV^{0}) centers in diamond are promising candidates for quantum networks because of their excellent optical properties and long spin coherence times. However, spin-dependent ...fluorescence in such defects has been elusive due to poor understanding of the excited state fine structure and limited off-resonant spin polarization. Here we report the realization of optically detected magnetic resonance and coherent control of SiV^{0} centers at cryogenic temperatures, enabled by efficient optical spin polarization via previously unreported higher-lying excited states. We assign these states as bound exciton states using group theory and density functional theory. These bound exciton states enable new control schemes for SiV^{0} as well as other emerging defect systems.
One of the most striking features of quantum mechanics is the profound effect exerted by measurements alone. Sophisticated quantum control is now available in several experimental systems, exposing ...discrepancies between quantum and classical mechanics whenever measurement induces disturbance of the interrogated system. In practice, such discrepancies may frequently be explained as the back-action required by quantum mechanics adding quantum noise to a classical signal. Here, we implement the “three-box” quantum game Aharonov Y, et al. (1991) J Phys A Math Gen 24(10):2315–2328 by using state-of-the-art control and measurement of the nitrogen vacancy center in diamond. In this protocol, the back-action of quantum measurements adds no detectable disturbance to the classical description of the game. Quantum and classical mechanics then make contradictory predictions for the same experimental procedure; however, classical observers are unable to invoke measurement-induced disturbance to explain the discrepancy. We quantify the residual disturbance of our measurements and obtain data that rule out any classical model by ≳7.8 standard deviations, allowing us to exclude the property of macroscopic state definiteness from our system. Our experiment is then equivalent to the test of quantum noncontextuality Kochen S, Specker E (1967) J Math Mech 17(1):59–87 that successfully addresses the measurement detectability loophole.
Abstract
Ensembles of nitrogen-vacancy (NV) centres in diamond are a leading platform for practical quantum sensors. Reproducible and scalable fabrication of NV-ensembles with desired properties is ...crucial, as is an understanding of how those properties influence performance. This work addresses these issues by characterising nitrogen-doped diamond produced by the chemical vapour deposition (CVD) method across a range of synthesis conditions. This is shown to produce material with widely differing absorption characteristics, which is linked to the level of defects other than substitutional nitrogen (N
S
) and NV. In such material, the achievable concentration of NV
−
(NV
−
) is found to be influenced by the as-grown properties. At the 10–20 ppm level for N
S
, the production of CVD-grown material with strain levels sufficient not to limit achievable device sensitivity is demonstrated and a favourable product of NV
−
and
T
2
*
is obtained. Additionally, reproducible properties over a batch of 23 samples from a single synthesis run are achieved, which appears promising for the scalability efforts underway in this area of research.
Neutral silicon vacancy centers (SiV^{0}) in diamond are promising candidates for quantum applications; however, stabilizing SiV^{0} requires high-purity, boron-doped diamond, which is not a readily ...available material. Here, we demonstrate an alternative approach via chemical control of the diamond surface. We use low-damage chemical processing and annealing in a hydrogen environment to realize reversible and highly stable charge state tuning in undoped diamond. The resulting SiV^{0} centers display optically detected magnetic resonance and bulklike optical properties. Controlling the charge state tuning via surface termination offers a route for scalable technologies based on SiV^{0} centers, as well as charge state engineering of other defects.
A Telecom O‑Band Emitter in Diamond Mukherjee, Sounak; Zhang, Zi-Huai; Oblinsky, Daniel G. ...
Nano letters,
04/2023, Letnik:
23, Številka:
7
Journal Article
Recenzirano
Odprti dostop
Color centers in diamond are promising platforms for quantum technologies. Most color centers in diamond discovered thus far emit in the visible or near-infrared wavelength range, which are ...incompatible with long-distance fiber communication and unfavorable for imaging in biological tissues. Here, we report the experimental observation of a new color center that emits in the telecom O-band, which we observe in silicon-doped bulk single crystal diamonds and microdiamonds. Combining absorption and photoluminescence measurements, we identify a zero-phonon line at 1221 nm and phonon replicas separated by 42 meV. Using transient absorption spectroscopy, we measure an excited state lifetime of around 270 ps and observe a long-lived baseline that may arise from intersystem crossing to another spin manifold.
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