The interaction between electrons and light is the most fundamental interaction in physics. Scientists from Goethe University Frankfurt performed an experiment in which they observed the Kapitza-Dirac effect for the first time in full temporal resolution.
First postulated almost nine decades ago, the Kapitza–Dirac effect is a quantum mechanical effect consisting of the diffraction of matter by a standing wave of light. In its original description, the effect is time-independent.
Researchers at EPFL and the Max Planck Institute have incorporated nonlinear optical phenomena into a transmission electron microscope (TEM), which uses electrons for imaging instead of light.
Nonlinear optics, the study of unpredictable light behavior in materials, has applications in various fields, from laser development to quantum information science. Integrating nonlinear optics into a TEM enables complex light interactions on a small chip, allowing for the miniaturization of devices in applications such as optical signal processing, telecommunications, sensing, and spectroscopy.
Theorists proposed an idea they called quantum teleportation—a means of transferring the identity of one particle to another over some distance.
The ultrafast dynamics and interactions of electrons in molecules and solids have long remained hidden from direct observation. For some time now, it has been possible to study these quantum-physical processes—for example, during chemical reactions, the conversion of sunlight into electricity in solar cells and elementary processes in quantum computers—in real time with a temporal resolution of a few femtoseconds (quadrillionths of a second) using two-dimensional electronic spectroscopy (2DES).
However, this technique is highly complex. Consequently, it has only been employed by a handful of research groups worldwide to date. Now a German-Italian team led by Prof. Dr. Christoph Lienau from the University of Oldenburg has discovered a way to significantly simplify the experimental implementation of this procedure. “We hope that 2DES will go from being a methodology for experts to a tool that can be widely used,” explains Lienau.
Two doctoral students from Lienau’s Ultrafast Nano-Optics research group, Daniel Timmer and Daniel Lünemann, played a key role in the discovery of the new method. The team has now published a paper in Optica describing the procedure.
Posted in computing, nanotechnology, quantum physics | Leave a Comment on Topological insulator nanowires reveal superconducting effect, bringing topological quantum computing closer to reality
Physicists at the University of Cologne have taken an important step forward in the pursuit of topological quantum computing by demonstrating the first-ever observation of Crossed Andreev Reflection (CAR) in topological insulator (TI) nanowires.
This finding, published under the title “Long-range crossed Andreev reflection in topological insulator nanowires proximitized by a superconductor” in Nature Physics, deepens our understanding of superconducting effects in these materials, which is essential for realizing robust quantum bits (qubits) based on Majorana zero-modes in the TI platform—a major goal of the Cluster of Excellence Matter and Light for Quantum Computing (ML4Q).
Quantum computing promises to revolutionize information processing, but current qubit technologies struggle with maintaining stability and error correction. One of the most promising approaches to overcoming these limitations is the use of topological superconductors, which can host special quantum states called Majorana zero-modes.
Once described by Einstein as “spooky action at a distance,” quantum entanglement may now seem less intimidating in light of new research findings.
Osaka Metropolitan University physicists have developed new, simpler formulas to quantify quantum entanglement in strongly correlated electron systems and applied them to study several nanoscale materials. Their results offer fresh perspectives into quantum behaviors in materials with different physical characteristics, contributing to advances in quantum technologies.
The study is published in Physical Review B.
Predictions of theories that combine quantum mechanics with gravity could be observed using highly sensitive photon detection in a tabletop experiment.
Quantum-gravity theories attempt to unite gravity and quantum mechanics. A proposed tabletop experiment called Gravity from the Quantum Entanglement of Space Time (GQuEST) would search for a predicted effect of such theories using a new type of interferometer—one that counts photons rather than measuring interference patterns. The GQuEST team has now calculated the sensitivity of their design and shown that it can recover the predicted signal 100 times faster than traditional interferometer setups [1].
Quantizing gravity implies that spacetime is not continuous—it becomes “pixelated” when you look at scales as small as 10−35 m, far too small to be probed in any experiment. However, certain quantum-gravity models predict that spacetime can fluctuate—a kind of spontaneous stretching and squeezing in the spacetime fabric that might produce observable effects [2]. “You couldn’t detect a single pixel, but you could detect the coherent fluctuations of many pixels,” says Caltech theorist Kathryn Zurek. She has formulated a “pixellon” model, which predicts that collective fluctuations inside an interferometer can cause a detectable frequency change, or modulation, in the interferometer’s output light [3].
