Phys.org November 14, 2024 Entanglement in hybrid quantum systems comprised of fundamentally different degrees of freedom, such as light and mechanics, is of interest for a wide range of applications in quantum technologies. Researchers in Germany proposed engineering bipartite entanglement between traveling acoustic phonons in a Brillouin active solid-state system and the accompanying light wave by applying optical pump pulses to state-of-the-art waveguides, exciting a Brillouin Stokes process. The pulsed approach, in a system operating in a regime orthogonal to standard optomechanical setups, allowed for the generation of entangled photon-phonon pairs, resilient to thermal fluctuations. They proposed an experimental platform […]
Tag Archives: S&T Germany
Hybrid fiber pump combiner could advance mid-IR laser systems
Phys.org October 9, 2024 Side-pumping fibre combiners offer several advantages in fibre laser design, including distributed pump absorption, reduced heat load, and improved flexibility and reliability. However, conventional fabrication methods face limitations due to significant differences in the thermal properties of pump-delivering silica fibres and signal-guiding fluoride-based fibres. Researchers in Germany addressed these challenges by introducing a design for a fuse-less side-polished (D-shaped) fibre-based pump combiner comprising multimode silica and double-clad fluoride-based fibres. The results demonstrated stable coupling efficiency over 8 hours of continuous operation under active thermal control. The pump combiner integrated into a linear Er-doped fibre laser cavity […]
Using microwaves to efficiently control diamond qubits
Nanowerk October 8, 2024 Group-IV color centers in diamond are promising candidates for quantum networks. However, the magnetic dipole transitions required for microwave spin control are suppressed, and strain is necessary to enable these transitions. Researchers in Germany found substantial improvement when they utilized a superconducting coplanar waveguide to measure SnV centers subjected to strain. They demonstrated coherent spin manipulation and obtained a Hahn echo coherence time of up to 2=430 μs. With dynamical decoupling they could prolong coherence to about sixfold improvement compared to earlier works. They observed a nearby coupling spin, which might serve as a quantum memory, thus […]
Chemists create gel to prevent leaks and boost lithium-ion battery life
Phys.org September 2, 2024 A key impediment for lithium battery technologies is the utilization of flammable organic solvent-based electrolytes which pose significant safety risks, and the recyclability of batteries has not reached the level required for transitioning to a circular economy. Researchers in Germany described poly(ionic liquid)-based dual network gel electrolytes as safer and sustainable alternative materials. The materials employed both, dynamic and covalent crosslinking, allowing the fabrication of mechanically stable gels with a high content (up to 65 wt%) of ionic liquid/salt both via thermal and photo polymerization. Mechanical stability, combined with enhanced ionic conductivity was achieved via the […]
Creating an ‘imprint’ on a super photon
Phys.org September 2, 2024 Thermalization of radiation by contact to matter is a well-known concept, but the application of thermodynamic methods to complex quantum states of light remains a challenge. Researchers in Germany observed Bose-Einstein condensation of photons into the hybridized ground state of a coupled four-site ring potential. They realized the periodically closed ring lattice superimposed by a weak harmonic trap for photons inside a spatially structured dye-filled microcavity. Photons thermalized to room temperature, and above a critical photon number macroscopically occupied the symmetric linear combination of the site eigenstates with zero phase winding, which constituted the ground state […]
A device to sort photon states could be useful for quantum optical computer circuits
Phys.org September 2, 2024 A quantum emitter interacting with photons in a single optical mode constitutes a one-dimensional atom. A coherent and efficiently coupled one-dimensional atom provides a large nonlinearity, enabling photonic quantum gates. Achieving a high coupling efficiency ( factor) and low dephasing is challenging. An international team of researchers (Switzerland, Germany) used a semiconductor quantum dot in an open microcavity as an implementation of a one-dimensional atom. With a weak laser input, they achieved an extinction of 99.2% in transmission and a concomitant bunching in the photon statistics, showcasing the reflection of the single-photon component and the transmission […]
Study sheds light on creative thinking
Phys.org August 15, 2024 Artificial intelligence systems and neural network models can reduce the intricacy of understanding creative cognition. The Hopfield neural network (HNN) is a simple model known for its biological plausibility in storing and retrieving neuron patterns. Researchers Germany implemented certain modifications to HNN as a step toward the larger framework of creative thinking-based association. The modifications included introducing pattern weights control, which provides a robust representation for content addressable memory and conceptual links in stored data. They identified two mechanisms controlling the transition from analytical to associative-based thinking, namely, the activation threshold of neurons, which acts as […]
Physicists develop new method to combine conventional internet with the quantum internet
Phys.org August 5, 2024 A promising and scalable route to enable quantum networking is encoding quantum information into the frequency of photons. While the cointegration of frequency-entangled photons with coherent information transmission is achieved via spectral multiplexing, more resource-efficient approaches are required. Researchers in Germany introduced and experimentally demonstrated a transceiver concept that enabled the transmission of coherent and frequency-entangled photons over a single-frequency channel. They leveraged the serrodyne technique via electro-optic phase modulation leading to very different dynamics for entangled and coherent photons. This enabled temporal multiplexing of the respective signals. They demonstrated the preservation of entanglement over the […]
A new metamaterial concept offering the potential for more efficient data storage
Nanowerk July 16, 2024 Researchers in Germany demonstrated that not just individual bits, but entire bit sequences can be stored in cylindrical domains. They used high perpendicular magnetic anisotropy synthetic antiferromagnets in the form of multilayer-based metamaterials whose antiferromagnetic interlayer exchanged energy was purposefully reduced below the out-of-plane demagnetization energy controlling magnetic domain formation. They demonstrated via macroscopic magnetometry and microscopic Lorentz transmission electron microscopy, that it was possible to stabilize nanometer-scale stripe and bubble textures consisting of ferromagnetic out-of-plane domain cores separated by antiferromagnetic in-plane Bloch-type domain walls. According to the researchers this coexistence of mixed ferromagnetic/antiferromagnetic order on […]
Scientists achieve first intercity quantum key distribution with deterministic single-photon source
Phys.org July 3, 2024 Quantum key distribution (QKD) enables secure communication. Semiconductor quantum dots (QDs) are a promising building block for quantum communication applications because of the deterministic emission of single photons with high brightness and low multiphoton contribution. Researchers in Germany reported on the first intercity QKD experiment using a bright deterministic single photon source. A BB84 [one time pad encryption] protocol based on polarisation encoding was realized using the high-rate single photons in the telecommunication C-band emitted from a semiconductor QD embedded in a circular Bragg grating structure. Utilizing the 79 km long link (equivalent to 130 km for the […]