Phys.org April 2, 2024 Continuous-variable (CV) quantum key distribution (QKD) with coherent states and coherent detection integrates well with existing telecommunication networks. Thus far, long-distance CV-QKD has only been demonstrated using a highly complex scheme where the local oscillator is transmitted, opening security loopholes for eavesdroppers, and limiting potential applications. Researchers in Denmark have demonstrated a long-distance CV-QKD experiment with a locally generated oscillator over a 100-kilometer fiber channel with a total loss of 15.4 decibels. This was done by controlling the phase noise–induced excess noise through a machine learning framework for carrier recovery and optimizing the modulation variance. They […]
Tag Archives: S&T Denmark
New chip-based beam steering device lays groundwork for smaller, cheaper lidar
Phys.org August 4, 2022 A conventional optical phased arrays (OPA) based on a waveguide grating array suffers from strong cross talk between adjacent waveguides when the pitch is a half-wavelength or less. Researchers in Denmark theoretically described and experimentally demonstrated a two-dimensional aliasing-free beam steering regime for an integrated OPA with the entire 180° field of view (FOV). They achieved this by using a half-wavelength-pitch waveguide array combined with a trapezoidal slab grating as a single emitter. The OPA had a low sidelobe level of <−19dB while the beam was steered from −40∘ to +40∘, breaking the trade-off between FOV […]
Revolutionary tool could meet future pandemics with accelerated response
Nanowerk April 4, 2022 Researchers in Denmark have developed a technique to identify pharmaceutical agents at nano scale. The process involves using soap-like bubbles as nano-containers to integrate elements from diverse disciplines such as synthetic biochemistry, nanotechnology, DNA synthesis, combinational chemistry, and AI. According to the researchers more than 40,000 different molecules can be synthesized and analyzed within seven minutes in an area smaller than a pinhead, drastically reducing the number of materials, energy, and economic cost for pharmaceutical companies…read more. TECHNICAL ARTICLE
Minimizing laser phase noise with machine learning
Phys.org January 3, 2022 One way of getting closer to an ultra-precise laser is to determine the phase noise and compensate for it. Researchers in Denmark have developed an algorithm that can analyze and find laser light patterns using machine learning, where a model for the noise is constantly being improved. On this basis they hope to develop a form of intelligent filter that continuously cleans the laser beam of noise. They were able to measure the noise up to very high frequencies, and the results contradicted the established understanding of laser noise. With the more detailed knowledge of the […]
COVID has had an impact on academics’ well-being
Phys.org December 1, 2021 Researchers in Denmark conducted research into how the situation has been for academics and have recommendations on how to mitigate potential adverse effects of the pandemic. The research into the academics’ well-being showed that as many as 40 percent of the almost 6,000 academics who took the survey reported a loss of research time. Over half of the Ph.D. candidates, postdocs and tenure-track academics reported COVID-related delays that they expect will prevent them from finishing their projects or meeting tenure track requirements in time. Their recommendations are – Prevent brain drain, invest in talent retention, especially […]
Novel physics gives rise to the highest coherence for microscopic lasers
Phys.org August 27, 2021 Despite considerable progress in microscale and nanoscale lasers the coherence length remains very limited. Researchers in Denmark explored the physics and applications of a new class of photonic devices using Fano interference which operates in bound-state-in the-continuum, induced by the Fano resonance. They showed experimentally as well as theoretically that the characteristics of such a bound-state-in-the-continuum can be harnessed to improve the coherence of the laser. They developed an advanced nanotechnology platform, called Buried Heterostructure Technology which allows realizing small, nanometer-sized regions of active material, where the light generation takes place, while the remaining laser structure […]
A complete platform for quantum computing
Phys.org August 13, 2021 A promising and potentially scalable hardware platforms and computational protocols is to combine a photonic platform with measurement-induced quantum information processing. Gate operations can be implemented through optical measurements on a cluster state. Researchers in Denmark designed and demonstrated the deterministic implementation of a multi-mode set of measurement-induced quantum gates in a large two-dimensional optical cluster state using phase-controlled continuous-variable quadrature measurements. Each gate is programmed into the phases of high-efficiency quadrature measurements, which execute the transformations by teleportation through the cluster state. They executed a small quantum circuit consisting of 10 single-mode gates and 2 […]
Collaboration yields promising material for quantum computing
Phys.org September 16, 2020 A one-dimensional topological superconductor with Majorana states bound to its ends can be realized by coupling a semiconductor nanowire to a superconductor in the presence of a strong magnetic field. However, the applied magnetic fields are detrimental to superconductivity, and constrain device layout, components, materials, fabrication, and operation. Using a ferromagnetic insulator instead of an applied field was theoretically proposed. Researchers in Denmark report transport measurements in hybrid nanowires using epitaxial layers of superconducting Al and the ferromagnetic insulator EuS on semiconducting InAs nanowires. They infer a remanent effective Zeeman field exceeding 1 T and observe stable […]
Blanket of light may give better quantum computers
Phys.org October 17, 2019 In their efforts to observe quantum phenomena on a macroscopic scale, researchers in Denmark managed to create a network of 30,000 entangled pulses of light arranged in a two-dimensional lattice distributed in space and time. They produced light beams with special quantum mechanical properties (squeezed states) and woven them together using optical fibre components to form a cluster state. An optical quantum computer will therefore not require costly and advanced refrigeration technology, its information-carrying light-based qubits in the laser light will be much more durable and it can be more easily be scaled to contain hundreds […]
An important step towards completely secure quantum communication network
Phys.org November 28, 2018 For practical long-distance quantum communication room-temperature atomic vapours are important. Atomic motion has so far limited the single-excitation lifetime in such systems to the microsecond range. Researchers in Denmark have demonstrated that lifespan of the quantum state at room temperature can be extended to about a quarter of a millisecond. They used a small glass container, filled with Cesium atoms, in which they were able to load, store and retrieve single photons from, the quantum states necessary for the repeater. This technique improves the life span of the quantum states at room temperature a hundred times…read […]