No Arabic abstract
The negatively-charged NV$^-$-center in diamond has shown great success in nanoscale, high-sensitivity magnetometry. Efficient fluorescence detection is crucial for improving the sensitivity. Furthermore, integrated devices enable practicable sensors. Here, we present a novel architecture which allows us to create NV$^-$-centers a few nanometers below the diamond surface, and at the same time in the mode field maximum of femtosecond-laser-written type-II waveguides. We experimentally verify the coupling efficiency, showcase the detection of magnetic resonance signals through the waveguides and perform first proof-of-principle experiments in magnetic field and temperature sensing. The sensing task can be operated via the waveguide without direct light illumination through the sample, which marks an important step for magnetometry in biological systems which are fragile to light. In the future, our approach will enable the development of two-dimensional sensing arrays facilitating spatially and temporally correlated magnetometry.
Rare-earth ion ensembles doped in single crystals are a promising materials system with widespread applications in optical signal processing, lasing, and quantum information processing. Incorporating rare-earth ions into integrated photonic devices could enable compact lasers and modulators, as well as on-chip optical quantum memories for classical and quantum optical applications. To this end, a thin film single crystalline wafer structure that is compatible with planar fabrication of integrated photonic devices would be highly desirable. However, incorporating rare-earth ions into a thin film form-factor while preserving their optical properties has proven challenging. We demonstrate an integrated photonic platform for rare-earth ions doped in a single crystalline thin film on insulator. The thin film is composed of lithium niobate doped with Tm3+. The ions in the thin film exhibit optical lifetimes identical to those measured in bulk crystals. We show narrow spectral holes in a thin film waveguide that require up to 2 orders of magnitude lower power to generate than previously reported bulk waveguides. Our results pave way for scalable on-chip lasers, optical signal processing devices, and integrated optical quantum memories.
Solid-state quantum sensors are attracting wide interest because of their exceptional sensitivity at room temperature. In particular, the spin properties of individual nitrogen vacancy (NV) color centers in diamond make it an outstanding nanoscale sensor of magnetic fields, electric fields, and temperature, under ambient conditions. Recent work on ensemble NV-based magnetometers, inertial sensors, and clocks have employed $N$ unentangled color centers to realize a factor of up to $sqrt{N}$ improvement in sensitivity. However, to realize fully this signal enhancement, new techniques are required to excite efficiently and to collect fluorescence from large NV ensembles. Here, we introduce a light-trapping diamond waveguide (LTDW) geometry that enables both high fluorescence collection ($sim20%$) and efficient pump absorption achieving an effective path length exceeding $1$ meter in a millimeter-sized device. The LTDW enables in excess of $2%$ conversion efficiency of pump photons into optically detected magnetic resonance (ODMR) fluorescence, a textit{three orders of magnitude} improvement over previous single-pass geometries. This dramatic enhancement of ODMR signal enables broadband measurements of magnetic field and temperature at less than $1$ Hz, a frequency range inaccessible by dynamical decoupling techniques. We demonstrate $sim 1~mbox{nT}/sqrt{mbox{Hz}}$ magnetic field sensitivity for $0.1$ Hz to $10$ Hz and a thermal sensitivity of $sim 400 ~mumbox{K}/sqrt{mbox{Hz}}$ and estimate a spin projection limit at $sim 0.36$ fT/$sqrt{mbox{Hz}}$ and $sim 139~mbox{pK}/sqrt{mbox{Hz}}$, respectively.
The mechanical properties of light have found widespread use in the manipulation of gas-phase atoms and ions, helping create new states of matter and realize complex quantum interactions. The field of cavity-optomechanics strives to scale this interaction to much larger, even human-sized mechanical objects. Going beyond the canonical Fabry-Perot cavity with a movable mirror, here we explore a new paradigm in which multiple cavity-optomechanical elements are wired together to form optomechanical circuits. Using a pair of optomechanical cavities coupled together via a phonon waveguide we demonstrate a tunable delay and filter for microwave-over-optical signal processing. In addition, we realize a tight-binding form of mechanical coupling between distant optomechanical cavities, leading to direct phonon exchange without dissipation in the waveguide. These measurements indicate the feasibility of phonon-routing based information processing in optomechanical crystal circuitry, and further, to the possibility of realizing topological phases of photons and phonons in optomechanical cavity lattices.
At low temperatures, microwave cavities are often preferred for the readout and control of a variety of systems. In this paper, we present design and measurements on an optomechanical device based on a 3-dimensional rectangular waveguide cavity. We show that by suitably modifying the electromagnetic field corresponding to the fundamental mode of the cavity, the equivalent circuit capacitance can be reduced to 29 fF. By coupling a mechanical resonator to the modified electromagnetic mode of the cavity, we achieved a capacitance participation ratio of 43 $%$. We demonstrate an optomechanical cooperativity, $C$$sim$40, characterized by performing measurements in the optomechanically-induced absorption (OMIA) limit. In addition, due to a low-impedance environment between the two-halves of the cavity, our design has the flexibility of incorporating a DC bias across the mechanical resonator, often a desired feature in tunable optomechanical devices.
Prospects of using metal hole arrays for the enhanced optical detection of molecular chirality in nanosize volumes are investigated. Light transmission through the holes filled with an optically active material is modeled and the activity enhancement by more than an order of magnitude is demonstrated. The spatial resolution of the chirality detection is shown to be of a few tens of nanometers. From comparing the effect in arrays of cylindrical holes and holes of complex chiral shape, it is concluded that the detection sensitivity is determined by the plasmonic near field enhancement. The intrinsic chirality of the arrays due to their shape appears to be less important.