Vacancy-related centres in silicon carbide are attracting growing attention because of their appealing optical and spin properties. These atomic-scale defects can be created using electron or neutron ...irradiation; however, their precise engineering has not been demonstrated yet. Here, silicon vacancies are generated in a nuclear reactor and their density is controlled over eight orders of magnitude within an accuracy down to a single vacancy level. An isolated silicon vacancy serves as a near-infrared photostable single-photon emitter, operating even at room temperature. The vacancy spins can be manipulated using an optically detected magnetic resonance technique, and we determine the transition rates and absorption cross-section, describing the intensity-dependent photophysics of these emitters. The on-demand engineering of optically active spins in technologically friendly materials is a crucial step toward implementation of both maser amplifiers, requiring high-density spin ensembles, and qubits based on single spins.
We present experimental evidence for scale invariant behaviour of the excitation spectrum in phase-fluctuating quasi-1d Bose gases after a rapid change of the external trapping potential. Probing ...density correlations in free expansion, we find that the temperature of an initial thermal state scales with the spatial extension of the cloud as predicted by a model based on adiabatic rescaling of initial eigenmodes with conserved quasiparticle occupation numbers. Based on this result, we demonstrate that shortcuts to adiabaticity for the rapid expansion or compression of the gas do not induce additional heating.
Many experiments in the physical sciences require high temporal resolution on multiple control channels and can benefit from conditional logic control of the experimental sequence patterns. We ...present LithPulser, a field programmable gate array (FPGA) based open-source digital pulser solution with 1 ns time resolution on 14 digital output channels. The pulser is set up on the affordable Xilinx Zynq-7010 FPGA in the form of the Red Pitaya STEMlab board 125-10. It offers up to 125 MHz bandwidth and a sequence duration of up to 4.2 s and features 16 sequence play control, including a conditional logic module reactive to input events in real-time. LithPulser is designed for a trial until success experimental use case.
We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-SiC28 ) and reveal not yet considered terms in the spin Hamiltonian, originated from the trigonal ...pyramidal symmetry of this spin-3/2 color center. These terms give rise to additional spin transitions, which would be otherwise forbidden, and lead to a level anticrossing in an external magnetic field. We observe a sharp variation of the photoluminescence intensity in the vicinity of this level anticrossing, which can be used for a purely all-optical sensing of the magnetic field. We achieve dc magnetic field sensitivity better than 100nT/Hz within a volume of 3×10−7mm3 at room temperature and demonstrate that this contactless method is robust at high temperatures up to at least 500 K. As our approach does not require application of radio-frequency fields, it is scalable to much larger volumes. For an optimized light-trapping waveguide of 3mm3 , the projection noise limit is below 100fT/Hz .
We report the levitation of a superconducting lead-tin sphere with 100 μm diameter (corresponding to a mass of 5.6 μg) in a static magnetic trap formed by two coils in an anti-Helmholtz ...configuration, with adjustable resonance frequencies up to 240 Hz. The center-of-mass motion of the sphere is monitored magnetically using a dc superconducting quantum interference device as well as optically and exhibits quality factors of up to 2.6×10^{7}. We also demonstrate 3D magnetic feedback control of the motion of the sphere. The setup is housed in a dilution refrigerator operating at 15 mK. By implementing a cryogenic vibration isolation system, we can attenuate environmental vibrations at 200 Hz by approximately 7 orders of magnitude. The combination of low temperature, large mass, and high quality factor provides a promising platform for testing quantum physics in previously unexplored regimes with high mass and long coherence times.
Photonic chips that integrate optical elements on a single device can process vast amounts of information rapidly. A new branch of this technology involves coupling light to cold atoms or ...Bose-Einstein condensates, the quantum nature of which provides a basis for new information-processing methods. The use of optical waveguides gives the light a small cross-section, making coupling to atoms efficient. In this Letter, we present the first waveguide chip designed to address a Bose-Einstein condensate along a row of independent junctions, which are separated by only 10 µm and have large atom-photon coupling. We describe a fully integrated, scalable design, and demonstrate 11 junctions working as intended, using a low-density cold atom cloud with as little as one atom on average in any one junction. The device suggests new possibilities for engineering quantum states of matter and light on a microscopic scale.
A microfabricated Fabry-Perot optical resonator has been used for atom detection and photon production with less than 1 atom on average in the cavity mode. Our cavity design combines the intrinsic ...scalability of microfabrication processes with direct coupling of the cavity field to single-mode optical waveguides or fibers. The presence of the atom is seen through changes in both the intensity and the noise characteristics of probe light reflected from the cavity input mirror. An excitation laser passing transversely through the cavity triggers photon emission into the cavity mode and hence into the single-mode fiber. These are first steps toward building an optical microcavity network on an atom chip for applications in quantum information processing.
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