Phys.org May 16, 2024 A new generation of diffractive components integrating specific geometry with additional features (flexibility, stretchability, rotation, and other approaches for tuning properties) extends the functionality of wavefront control. Researchers in Russia demonstrated an innovative approach to control the THz wavefront via a layered composition of spiral zone plates (SZPs) with tunable mutual orientation and scaling. As a proof of concept, they designed the SZP with experimental characterization of the resultant vortex beams. For each single SZP, a flexible element was proposed based on thin film of single-walled carbon nanotubes deposited on a stretchable substrate. The diffraction element […]
Physicists demonstrate first metro-area quantum computer network in Boston
Phys.org May 15, 2024 A team of researchers in the US (MIT, Harvard University, industry) demonstrated a two-node quantum network composed of multi-qubit registers based on silicon-vacancy (SiV) centres in nanophotonic diamond cavities integrated with a telecommunication fibre network. Remote entanglement was generated by the cavity-enhanced interactions between the electron spin qubits of the SiVs and optical photons. Serial spin-photon entangling gate operations with time-bin qubits were used for robust entanglement of separated nodes. Long-lived nuclear spin qubits were used to provide second-long entanglement storage and integrated error detection. By integrating efficient bidirectional quantum frequency conversion of photonic communication qubits […]
Physicists reach atomic-scale telegraphy with light
Phys.org May 8, 2024 By exploiting linear interaction with tip-confined evanescent light fields, near-field microscopy has reached even higher resolution, prompting a vibrant research field by exploring the nanocosm in motion. Yet the finite radius of the nanometre-sized tip apex has prevented access to atomic resolution. Researchers in Germany leveraged extreme atomic nonlinearities within tip-confined evanescent fields to push all-optical microscopy to picometric spatial and femtosecond temporal resolution. They discovered an unprecedented and efficient non-classical near-field response, in phase with the vector potential of light and strictly confined to atomic dimensions. This ultrafast signal was characterized by an optical phase […]
Researchers develop world’s smallest quantum light detector on a silicon chip
Phys.org May 17, 2024 Quantum noise–limited homodyne detectors have applications across quantum technologies, and they comprise photonics and electronics. Researchers in the UK developed a quantum noise–limited monolithic electronic-photonic integrated homodyne detector, with a footprint of 80 micrometers by 220 micrometers, fabricated in a 250-nanometer lithography bipolar CMOS process. They measured a 15.3-gigahertz 3-decibel bandwidth with a maximum shot noise clearance of 12 decibels and shot noise clearance out to 26.5 gigahertz, when measured with a 9–decibel-milliwatt power local oscillator. This performance was enabled by monolithic electronic-photonic integration, which went below the capacitance limits of devices made up of separate […]
Researchers make a surprising discovery: Magnetism in a common material for microelectronics
Phys.org May 15, 2024 Nickel monosilicide (NiSi) is widely used to connect transistors in semiconductor circuits. Earlier theoretical calculations had incorrectly predicted that NiSi was not magnetic. As a result, researchers had never fully explored magnetism in NiSi. An international team of researchers (USA – University of Missouri, Oak Ridge National Laboratory, Austria, Poland) showed that NiSi metal could provide suitable new platform. The study showed high-temperature antiferromagnetism in single-crystal NiSi with Néel temperature. Antiferromagnetic order in NiSi was accompanied by non-centrosymmetric magnetic character with small ferromagnetic component in the a–c plane. It was found that NiSi manifests distinct magnetic […]
Researchers wrestle with accuracy of AI technology used to create new drug candidates
Science Daily May 16, 2024 AlphaFold2 (AF2) models have had wide impact, but they have had mixed success in retrospective ligand recognition. An international team of researchers (USA – UC San Francisco, University of North Carolina, Harvard University, Stanford University, Ukraine) prospectively docked large libraries against unrefined AF2 models of the σ2 and 5-HT2A receptors, testing hundreds of new molecules and comparing results to docking against the experimental structures. Hit rates were high and similar for the experimental and the AF2 structures, as were affinities. The success of docking against the AF2 models was achieved despite differences in orthosteric residue […]
Scientists create black arsenic visible infrared photodetectors
Phys.org May 8, 2024 Black arsenic as 2-dimensional van der Waals layered material is a promising candidate for electronic and photonic applications because of tunable bandgap layers, high carrier mobility, and anisotropic transport feature. However, the potential of black arsenic for engineering nanophotoelectronic devices in the range from visible to near-infrared wavelength has not been reported. Researchers in China used black arsenic in visible–infrared detectors at the range from 520 to 1,550 nm, exhibiting a photoresponsivity of 0.4 A·W−1 and a detective of 1.37 × 108 Jones… read more. Open Access TECHNICAL ARTICLE
Scientists create an ‘optical conveyor belt’ for quasiparticles
Phys.org May 14, 2024 Periodic temporal modulation of Hamiltonians can induce geometrical and topological phenomena in the dynamics of quantum states. Using the interference between two lasers an international team of researchers (Japan, USA – industry, Singapore, Australia, Germany) demonstrated an off-resonant optical lattice for a polariton condensate with controllable potential depths and nearest-neighbour coupling strength. Temporal modulation was introduced via a gigahertz frequency detuning between pump lasers, creating a polariton ‘conveyor belt’. The breaking of time-reversal symmetry caused band structures to become non-reciprocal and acquired a universal tilt. The non-reciprocal tilting was connected to the non-trivial topology of the […]
Scientists demonstrate the survival of quantum coherence in a chemical reaction involving ultracold molecules
Phys.org May 16, 2024 Chemical reactions, where bonds break and form, are highly dynamic quantum processes. A fundamental question is whether coherence can be preserved in chemical reactions and then harnessed to generate entangled products. Researchers at Harvard University investigated this by studying the 2KRb → K2 + Rb2 reaction at 500 nK, focusing on the nuclear spin degrees of freedom. They prepared the initial nuclear spins in KRb in an entangled state by lowering the magnetic field to where the spin-spin interaction dominated and characterized the preserved coherence in nuclear spin wavefunction after the reaction. They observed an interference […]
Thermoelectric materials approach boosts band convergence to avoid time-consuming trial-and-error approach
Phys.org May 16, 2024 Electronic band convergence can have a beneficial impact on thermoelectric performance, but finding the right band-converged compositions is still time-consuming. A team of researchers in the US (University of Houston, Rice University) proposed a method for designing a series of compositions with simultaneous band convergence in the high-entropy YbxCa1−xMgyZn2−ySb2 material by zeroing the weighted sum of crystal-field splitting energies of the parent compounds. They found that such compositions have both larger power factors and lower thermal conductivities and that one of them exhibited a large thermoelectric figure of merit value in comparison with to other p-type […]