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Solid-state quantum emitters (QEs) are fundamental in photonic-based quantum information processing. There is strong interest to develop high-quality QEs in III-nitride semiconductors because of their sophisticated manufacturing driven by large and growing applications in optoelectronics, high voltage power transistors, and microwave amplifiers. Here, the generation and direct integration of QEs in an aluminum nitride-based photonic integrated circuit platform is reported. For individual waveguide-integrated QEs, an off-chip count rate exceeding 6 × 104 counts per second (cps; saturation rate >8.6 × 104 cps) is measured at room temperature under continuous-wave (CW) excitation. In an unpatterned thin-film sample, antibunching with g(2)(0) ∼0.08 and photon count rates exceeding 8 × 105 cps (saturation rate >1 × 106 cps) are measured at room temperature under CW excitation. Although spin and detailed optical line width measurements are left for future work, these results already show the potential for high-quality QEs monolithically integrated in a wide range of III-nitride device technologies that would enable new quantum device opportunities and industrial scalability., United States. Army Research Office MURI ((Ab-Initio Solid-State Quantum Materials Grant W911NF-18-1-0431), National Science Foundation (U.S.). Research Advanced by Interdisciplinary Science and Engineering (Grant CHE-1839155), Air Force Research Laboratory. RITA program ( FA8750-16-2-0141), National Research Foundation of Korea (Grants 2015R1A6A3A03020926 and 2018R1D1A1B07043390)

Squeezing of the electromagnetic vacuum is an essential metrological technique used to reduce quantum noise in applications spanning gravitational wave detection, biological microscopy, and quantum information science. In superconducting circuits, the resonator-based Josephson-junction parametric amplifiers conventionally used to generate squeezed microwaves are constrained by a narrow bandwidth and low dynamic range. In this work, we develop a dual-pump, broadband Josephson traveling-wave parametric amplifier that combines a phase-sensitive extinction ratio of 56 dB with single-mode squeezing on par with the best resonator-based squeezers. We also demonstrate two-mode squeezing at microwave frequencies with bandwidth in the gigahertz range that is almost two orders of magnitude wider than that of contemporary resonator-based squeezers. Our amplifier is capable of simultaneously creating entangled microwave photon pairs with large frequency separation, with potential applications including high-fidelity qubit readout, quantum illumination and teleportation.

Solid-state qubits with transition frequencies in the microwave regime, such as superconducting qubits, are at the forefront of quantum information processing. However, high-fidelity, simultaneous control of superconducting qubits at even a moderate scale remains a challenge, partly due to the complexities of packaging these devices. Here, we present an approach to microwave package design focusing on material choices, signal line engineering, and spurious mode suppression. We describe design guidelines validated using simulations and measurements used to develop a 24-port microwave package. Analyzing the qubit environment reveals no spurious modes up to 11GHz. The material and geometric design choices enable the package to support qubits with lifetimes exceeding 350 {\mu}s. The microwave package design guidelines presented here address many issues relevant for near-term quantum processors., Comment: 15 pages, 9 figures

Nanodiamonds hosting colour centres are a promising material platform for various quantum technologies. The fabrication of non-aggregated and uniformly-sized nanodiamonds with systematic integration of single quantum emitters has so far been lacking. Here, we present a top-down fabrication method to produce 30.0$\pm$5.4 nm uniformly-sized single-crystal nanodiamonds by block copolymer self-assembled nanomask patterning together with directional and isotropic reactive ion etching. We show detected emission from bright single nitrogen vacancy centres hosted in the fabricated nanodiamonds. The lithographically precise patterning of large areas of diamond by self-assembled masks and their release into uniformly sized nanodiamonds open up new possibilities for quantum information processing and sensing., Comment: 15 pages, 2 figures

Quantum emitters in solids are being developed for a range of quantum technologies, including quantum networks, computing, and sensing. However, a remaining challenge is the poor photon collection due to the high refractive index of most host materials. Here we overcome this limitation by introducing monolithic parabolic reflectors as an efficient geometry for broadband photon extraction from quantum emitter and experimentally demonstrate this device for the nitrogen-vacancy (NV) center in diamond. Simulations indicate a photon collection efficiency exceeding 75% across the visible spectrum and experimental devices, fabricated using a high-throughput gray scale lithography process, demonstrating a photon extraction efficiency of (41 ± 5)%. This device enables a raw experimental detection efficiency of (12 ± 1)% with fluorescence detection rates as high as (4.114 ± 0.003) × 106 counts per second (cps) from a single NV center. Enabled by our deterministic emitter localization and fabrication process, we fin...

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 $T_1$ $>$ 10 ms, and the coherence time, $T_2$ 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., 6 pages, 4 figures

We investigate the optical properties of quantum emitters formed in diamond after the implantation of Pb and subsequent high-temperature annealing. We find narrow-band emission in two spectral ranges, indicating multiple classes of Pb-related color centers.

© 2016 Optical Society of America. We demonstrate that strain control of exfoliated hexagonal boron nitride allows spectral tuning of single photon emitters over 6 meV. We propose a material processing that sharply improves the single-photon purity with g(2)(0) = 0.077, and brightness with emission rate exceeding 107counts/sec at saturation.

© 2017 IEEE. Non-classical light sources, such as atoms and atom-like emitters play central roles in many areas of quantum information processing with applications as single photon generators, sources for nonlinearity and quantum memories. Solid-state quantum emitters have attracted growing interest due to the promise of combining remarkable optical properties with the convenience of scalability [1]. In recent years, there has been tremendous progress in developing quantum emitter systems based on crystallographic defects in wide-bandgap semiconductors. Nitrogen vacancies (NV) in diamond were among the first studied systems due to the well-defined optical transitions as well as electronic spin states that can be controlled optically. Quantum spins in diamond are among the most advanced systems in solid state for quantum based technologies such as quantum computing or quantum sensing [2]. Nevertheless, solid-state quantum emitters are not only limited to diamond and efforts to engineer single photon emitters (SPE) based on atom-like defects in scalable system have expanded beyond NV centers in diamond. Similar quantum emitters have been discovered in many other wide-bandgap host materials, including silicon carbide (SiC), III-nitride semiconductors such as gallium nitride (GaN) and aluminum nitride (AlN), and layered materials such as hexagonal boron nitride (hBN) [1]. Here, we will review our recent progress in developing and characterizing new quantum emitters in wide-bandgap semiconductors, and consider their applications as quantum light sources and sensors.

Efficient, on-demand, and robust single photon emitters (SPEs) are important to a wide varity of applications in quantum information processing [1]. Over the past decade, color centers in solid-state systems have emerged as excellent SPEs [2] and have also been shown to provide optical access to internal spin states at room and cyogenic temperatures. Color centers in diamond [3] and silicon carbide [4] are among the most intensively studied SPEs. Recently, other cost-efficient wide-bandgap materials have become attractive as potential host materials. Theoretical calculations show that aluminum nitride (AlN) with a bandgap of 6.015 eV can serve as a stable environment for well isolated SPEs with optically accessible spin states [5].