161 research outputs found
Lead-related quantum emitters in diamond
We report on quantum emission from Pb-related color centers in diamond following ion implantation and high-temperature vacuum annealing. First-principles calculations predict a negatively charged Pb-vacancy (PbV) center in a split-vacancy configuration, with a zero-phonon transition around 2.4 eV. Cryogenic photoluminescence measurements performed on emitters in nanofabricated pillars reveal several transitions, including a prominent doublet near 520 nm. The splitting of this doublet, 5.7 THz, exceeds that reported for other group-IV centers. These observations are consistent with the PbV center, which is expected to have a combination of narrow optical transitions and stable spin states, making it a promising system for quantum network nodes.U.S. Army Research Laboratory. Center for Distributed Quantum InformationNational Science Foundation (U.S.). Graduate Research Fellowship ProgramNational Science Foundation (U.S.) (Grant DMR-1231319)United States. National Aeronautics and Space Administration (Space Technology Research Fellowship)MIT-Harvard Center for Ultracold Atoms MIT International Science and Technology Initiativ
Demonstrating sub-3 ps temporal resolution in a superconducting nanowire single-photon detector
Improving the temporal resolution of single photon detectors has an impact on
many applications, such as increased data rates and transmission distances for
both classical and quantum optical communication systems, higher spatial
resolution in laser ranging and observation of shorter-lived fluorophores in
biomedical imaging. In recent years, superconducting nanowire single-photon
detectors (SNSPDs) have emerged as the highest efficiency time-resolving
single-photon counting detectors available in the near infrared. As the
detection mechanism in SNSPDs occurs on picosecond time scales, SNSPDs have
been demonstrated with exquisite temporal resolution below 15 ps. We reduce
this value to 2.70.2 ps at 400 nm and 4.60.2 ps at 1550 nm, using a
specialized niobium nitride (NbN) SNSPD. The observed photon-energy dependence
of the temporal resolution and detection latency suggests that intrinsic
effects make a significant contribution.Comment: 25 pages, 9 figure
Transform-limited photons from a coherent tin-vacancy spin in diamond
Solid-state quantum emitters that couple coherent optical transitions to
long-lived spin qubits are essential for quantum networks. Here we report on
the spin and optical properties of individual tin-vacancy (SnV) centers in
diamond nanostructures. Through cryogenic magneto-optical and spin
spectroscopy, we verify the inversion-symmetric electronic structure of the
SnV, identify spin-conserving and spin-flipping transitions, characterize
transition linewidths, measure electron spin lifetimes and evaluate the spin
dephasing time. We find that the optical transitions are consistent with the
radiative lifetime limit even in nanofabricated structures. The spin lifetime
is phononlimited with an exponential temperature scaling leading to
10 ms, and the coherence time, reaches the nuclear spin-bath limit upon
cooling to 2.9 K. These spin properties exceed those of other
inversion-symmetric color centers for which similar values require millikelvin
temperatures. With a combination of coherent optical transitions and long spin
coherence without dilution refrigeration, the SnV is a promising candidate for
feasable and scalable quantum networking applications
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