Phys.org April 16, 2024 Harnessing the asymmetric electronic population in the conduction band induced by an intense single-color circularly polarized laser pulse an international team of researchers (Japan, India, Germany) developed a universal method to generate ultrafast photocurrent in both inversion-symmetric and inversion-broken Weyl semimetals with degenerate Weyl nodes at the Fermi level. They found that the induced photocurrent could be tailored by manipulating helicity and ellipticity of the employed laser. Their approach generated photocurrent in realistic situations when the Weyl nodes were positioned at different energies and had finite tilt along a certain direction. According to the researchers their […]
Tag Archives: Quantum technologies
Valley-transistor in two-dimensional materials – an ingredient for all-optical quantum technologies
Nanowerk April 23, 2023 Electrons in two-dimensional materials possess an additional quantum attribute, the valley pseudospin, labeled as K and K’—analogous to the spin up and spin down. Most of the research to achieve valley-selective excitations in valleytronics depends on resonant circularly polarized light with a given helicity. Not only acquiring valley-selective electron excitation but also switching the excitation from one valley to another is quintessential for bringing valleytronics-based technologies to reality. Researchers in India introduced a coherent control protocol to initiate valley-selective excitation, de-excitation, and switch the excitation from one valley to another on the fly within tens of […]
Scientists turn single molecule clockwise or counterclockwise on demand
Phys.org December 21, 2022 Complexes containing rare-earth ions attract great attention for their technological applications ranging from spintronic devices to quantum information science. While charged rare-earth coordination complexes are ubiquitous in solution, they are challenging to form on materials surfaces that would allow investigations for potential solid-state applications. A team or researchers in the US (Argonne National Laboratory, Ohio University, University of Illinois) has demonstrated formation and atomically precise manipulation of rare-earth complexes on gold surface. Although they are composed of multiple units held together by electrostatic interactions, the entire complex rotates as a single unit when electrical energy is […]
Transporting of two-photon quantum states of light through a phase-separated Anderson localization optical fiber
Phys.org November 23, 2022 Experiments in the past have demonstrated Anderson localization in optical fibers, classical or conventional light, in two dimensions while propagating it through the third dimension. An international team of researchers (Spain, USA – industry, Italy) engineered the optical setup to send the quantum light through the phase-separated Anderson localization fiber and detected its arrival with the single-photon avalanche diode (SPAD) array camera. It enabled them not only to detect and identify them as pairs, as they arrived at the same time. As the pairs are quantum correlated, knowing where one of the two photons is detected […]
Researchers control individual light quanta at very high speed
Phys.org November 21, 2022 An international team of researchers (Spain, Germany) fabricated a dynamically reconfigurable integrated photonic circuit comprising integrated quantum dots (QDs), a Mach-Zehnder interferometer (MZI) and surface acoustic wave (SAW) transducers directly fabricated on a monolithic semiconductor platform to demonstrate on-chip single photon generation by the QD and its sub-nanosecond dynamic on-chip control. Two independently applied SAWs piezo-optomechanically rotated the single photon in the MZI. In the MZI, SAWs imprinted a time-dependent optical phase and modulated the qubit rotation to the output superposition state. This enabled dynamic single photon routing with frequencies exceeding one gigahertz. The combination of […]
New device gets scientists closer to quantum materials breakthrough
Phys.org June 17, 2022 An international team of researchers (USA – UC Berkeley, University of Nebraska, Argonne National Laboratory, Canada) has found a way to combine the advantages of light and matter at room temperature suitable for finding the global minimum of mathematical formulations at room temperature. They used solution-grown halide perovskite grown under nanoconfinement. This produced exceptional smooth single-crystalline large crystals with great optical homogeneity. Its material properties could enable future studies at room temperature rather than ultracold temperatures. They showed that XY spin lattice with many coherently coupled condensates that can be constructed as a lattice with a […]
Ultra-thin film of magnetite optimized for spintronics
Phys.org November 17, 2021 Magnetite has physical properties which may make it useful for spintronics technology. However, it is difficult to fabricate magnetite with high crystallinity owing to the imperfection of the substrate surface. An international team of researchers (Japan, China) has developed a chemical polishing technique—known by its acronym CARE—to prepare an atomically flat and highly ordered magnesium oxide substrate. CARE treatment of the substrate enabled the thin film to undergo a temperature-dependent resistivity change—known as the Verwey transition—of a factor of 5.9. The results have important applications – quantum computing technologies may rely on spintronics to optimize logistical, […]
Trapping spins with sound
Science Daily November 1, 2021 Lattice defects in crystals often come along with certain magnetic properties. To use them as promising systems for applications in quantum technologies an international team of researchers (Germany, Russia) has developed an efficient method to control their spin states using surface acoustic waves (SAW). They demonstrated a giant interaction between the strain field of SAW and the excited-state spin of silicon vacancies in silicon carbide, which is about two orders of magnitude stronger than in the ground state. The simultaneous spin driving in the ground and excited states with the same SAW leads to the […]
Making progress towards quantum technologies based on magnetic molecules
Nanowerk October 15, 2021 Electrical control of spins at the nanoscale offers significant architectural advantages in spintronics. However, the electric-field sensitivities reported so far are rather weak. An international team of researchers (UK, Spain) showed that one path is to identify an energy scale in the spin spectrum that is associated with a structural degree of freedom with a substantial electrical polarizability. They studied an example of a molecular nanomagnet in which a small structural distortion establishes clock transitions in the spin spectrum; the fact that this distortion is associated with an electric dipole allowed them to control the clock-transition energy […]
A highly simplified way to predict quantum light-matter interactions
Phys.org October 13, 2021 Calculating quantum light-matter takes enormous amounts of time and computing power—it also becomes very cumbersome. An international team of researchers (Germany, Sweden, Austria) has found a simple way to circumvent this problem by reshaping the equation so that the material part itself accounts for the quantum mechanical uncertainty of the light, far fewer additional photons are needed to describe the combined system of quantum light and matter. The new approach can capture most features of this extreme limit without the need to consider any photon at all. Adding just a few photons is enough to provide […]