Phys.org June 9,2021 Optically detected magnetic resonance (ODMR) technology offers a readout approach to detect the spin state. Conventional ODMR detection of solid-state spin states are almost all under Strokes excitation, which requires that the excitation laser has higher energy than emitted photons. An international team of researchers (China, Hungary) investigated the dependence of laser power and temperature on AS excited ODMR signals, the researchers proved that the AS photoluminescence (PL) was induced by phonon-assisted single photon absorption process and was applicable to all-optical high-temperature temperature sensing. Based on this, they found that AS and Strokes excited ODMR followed similar […]
Tag Archives: Quantum technology
Future sparkles for diamond-based quantum technology
Science Daily May 17, 2021 Advancement of diamond based photonic circuitry requires robust fabrication protocols of key components – including diamond resonators and cavities. Researchers in Australia have developed a new hard masking method, which uses a thin metallic tungsten layer to pattern the diamond nanostructure, enabling the creation of one-dimensional photonic crystal cavities. The use of tungsten instead of a more conventional silicon oxide layer enables good repeatability and reliability of the fabrication procedures. The process yields high quality diamond cavities with quality factors (Q-factors) approaching 1 × 104. They showed that the cavities can be picked up and […]
Light meets superconducting circuits
EurekAlert May 10, 2021 Realizing the full potential of quantum computers requires a significant increase in the number of qubits to store and manipulate quantum information. To prevent contaminating quantum signals by thermal noise, the superconducting quantum systems must operate at ultra-low temperatures. An international team of researchers (Switzerland, India) has developed a novel approach that uses light to read out superconducting circuits. They replaced low-noise high-electron mobility transistors and coaxial cables with a lithium niobate electro-optical phase modulator and optical fibers. Microwave signals from superconducting circuits modulate a laser carrier and encode information on the output light at cryogenic […]
Researchers generate tunable twin particles of light
Phys.org May 11, 2021 A team of researchers in the US (University of Maryland, University of Illinois) demonstrated a tunable source of indistinguishable photon pairs using dual-pump spontaneous four-wave mixing in a topological system comprising a two-dimensional array of resonators. They exploited the linear dispersion of the topological edge states to tune the spectral bandwidth (by about 3.5×), and thereby, tuned quantum interference between generated photons by tuning the two pump frequencies. They demonstrated energy−time entanglement and, using numerical simulations, confirmed the topological robustness of the source. Their results could lead to tunable, frequency-multiplexed quantum light sources for photonic quantum […]
Researchers realize coherent storage of light over one hour
Phys.org May 10, 2021 One solution for remote quantum communication lies in quantum memories: photons are stored in long-lived quantum memory (quantum flash drive) and then quantum information is transmitted by the transportation of the quantum memory. Researchers in China adopted the spin wave atomic frequency comb (AFC) protocol in a ZEFOZ field (ZEFOZ-AFC) method to implement long-lived storage of light signals. They used dynamical decoupling to protect spin coherence and extend storage time. They demonstrated coherent storage of light in an atomic frequency comb memory over 1 hour with a fidelity of 96.4%. The study meets the basic requirements […]
Ion beams mean a quantum leap for color-center qubits
Phys.org April 28, 2021 An international team of researchers (USA – Lawrence Berkeley National Laboratory, Finland, Singapore, Germany) has measured depth-resolved photoluminescence of nitrogen-vacancy (NV−) centers formed along the tracks of swift heavy ions (SHIs) in synthetic single crystal diamonds that had been doped with nitrogen during crystal growth. Analysis of the spectra showed that NV− centers are formed preferentially within regions where electronic stopping processes dominate and not at the end of the ion range where elastic collisions lead to the formation of vacancies and defects. Thermal annealing further increased NV yields after irradiation with SHIs preferentially in regions […]
New two-dimensional material
Science Daily April 27, 2021 An international team of researchers (USA – Carnegie Institution for Science, Howard University, University of Chicago, Argonne National Laboratory, Germany, France, Russia, Sweden, the Netherlands, China) used the laser-heated diamond anvil cell technique with pressures of up to 100 gigapascals, to synthesize a Dirac material beryllonitrene (BeN4). These are beryllium polynitrides, some of which conform to the monoclinic, others to the triclinic crystal system. The triclinic beryllium polynitrides exhibit an unusual characteristic when the pressure drops. They take on a crystal structure made up of layers. Each layer contains zigzag nitrogen chains connected by beryllium […]
A two-qubit engine powered by entanglement and local measurements
Phys.org April 26, 2021 As an immediate consequence of the effect of quantum mechanics, the measuring device provides both energy and entropy to the quantum system. Previously an international team of researchers (France, USA – University of Rochester, Washington University, Chapman University) introduced the proof of concept for a measurement-fueled engine based on a single qubit. Now they have introduced a two-qubit engine that is powered by entanglement and local measurements. Energy is extracted from the detuned qubits coherently exchanging a single excitation. Generalizing to an N-qubit chain, they showed that the low energy of the first qubit can be […]
New computing algorithms expand the boundaries of a quantum future
Phys.org April 6, 2021 Researchers at the Fermi National Accelerator Laboratory have developed two new algorithms that build upon existing work to in the field to further diversify the types of problems quantum computers can solve. To get around the probabilistic nature of superpositions the researchers developed the non-Boolean quantum amplitude amplification algorithm which is open to more tasks. A second algorithm they introduced dubbed the quantum mean estimation algorithm allows scientists to estimate the average. Both algorithms do away with having to reduce scenarios into computations with only two types of output, and instead allow for a range of […]
Researchers report breakthrough that enables practical semiconductor spintronics
Phys.org April 8, 2021 By remote spin filtering of InAs quantum-dot electrons via an adjacent tunnelling-coupled GaNAs spin filter an international team of researchers (Sweden, Finland, Japan) demonstrated successful generation of conduction electron spin polarization exceeding 90% at room temperature without a magnetic field in a non-magnetic all-semiconductor nanostructure, which remains high even up to 110 °C. They also showed that the quantum-dot electron spin can be remotely manipulated by spin control in the adjacent spin filter, paving the way for remote spin encoding and writing of quantum memory as well as for remote spin control of spin–photon interfaces. This work […]