Researchers created an electrically tunable quantum nanoscale corral that traps charged excitons and enables precise electrical control of tiny light sources, including their brightness, color and quantum states, the team, led by Boston College physicists, reports today in Nature Nanotechnology.
The findings open new ways to control hybrid charge, photon and spin quantum states.
Two strongly coupled superconducting states can disguise themselves as a single energy gap in ultrathin materials.
Two ultrathin superconductors appeared to have a simple internal structure, but closer measurements revealed something more complex. Instead of relying on one superconducting state, each material contains two strongly coupled states whose combined behavior makes them look like a single one.
The finding resolves a persistent mystery surrounding these materials and provides a more accurate picture of how their superconductivity works. That understanding could eventually help researchers develop improved materials for quantum computers, ultra-efficient electronics, advanced sensors, and other superconducting technologies.
Maintaining a long-distance relationship may be difficult for humans, but it’s even more difficult for entangled states.
The longer the fiber, the harder it becomes to keep the two quantum memories linked.
Overcoming this tyranny of distance has been one of the major challenges of quantum communication.
Scientists from Rice University in the U.S. have developed a way to precisely tune the temperature inside a trapped-ion simulator. The breakthrough means they will be able to run quantum simulations at precise temperatures that better reflect real-world conditions.
Trapped-ion simulators are quantum devices that isolate charged particles inside a sealed vacuum chamber, using electric fields to hold them in place. They mimic and study complex quantum systems, such as chemical reactions or exotic materials, that are too difficult for ordinary computers to calculate.
Temperatures inside these devices are typically kept as close as possible to absolute zero so that thermal motion does not disrupt calculations or cause errors. But researchers lacked a suitable way to set the temperature without accidentally changing how fast the system loses energy. This meant that studies were mostly stuck using absolute zero or uncontrolled high temperatures.
One of the most famous and intriguing results of quantum mechanics is the finding that fundamental particles, such as electrons, cannot be pinned down to one single location. Instead, a particle is described by its “wavefunction,” which allows researchers to derive probability distributions—a sort of mathematical map that shows the possibilities—of fundamental properties such as its position and momentum. In particular, the electron wavefunctions within a molecule, known as “molecular orbitals,” carry information about how the molecule interacts with its surroundings. For example, they show how it may absorb light or how a chemical reaction might take place.
As a consequence, knowledge of the complete three-dimensional wavefunction is highly desirable, but imaging the wavefunction has proven to be a major experimental challenge. An interdisciplinary research team at the University of Göttingen has now managed to image the three-dimensional wavefunction of a nanometer-sized organic molecule. They overcame the limitations by combining state-of-the-art photoelectron spectroscopy with powerful mathematical algorithms. The results are published in Nature Communications.
Bose-Einstein condensates (BECs) are often described as a “fifth state of matter”: a quantum state in which many particles lose their individual identities and behave as one collective object. For more than 60 years, researchers have sought to create such condensates from excitons—electron-hole pairs—as a solid-state route to macroscopic quantum coherence, which is useful for quantum technologies. This has been difficult to realize in controllable semiconductor devices because optically generated excitons have very short lifetimes of around a billionth of a second, and BECs are normally attained with ultracold gases in a vacuum.
But now, a team led by Lawrence Berkeley National Laboratory (Berkeley Lab) has observed a tunable BEC of excitons at high temperature in an atomically thin semiconductor. The findings, published in Nature, reveal not only that the excitons form a BEC but also that the condensate has an internal structure that can be switched by a magnetic field.
The work enables a new platform for studying quantum fluids in solid materials. (A quantum fluid is an exotic state of matter in which gases of electrons or other particles behave collectively like a fluid.) It also has implications for future quantum simulations, coherent optoelectronics in next-generation telecommunications and computing, and exciton-based devices enabling faster, more efficient computing.
Researchers at the 4th Physics Institute of the University of Stuttgart and the Istituto Italiano di Tecnologia (IIT) in Milan have demonstrated a new mechanism for directing light in a naturally hyperbolic van der Waals material without conventional nanofabricated waveguides. The discovery opens new possibilities for integrated photonics, on-chip optical communication and future quantum technologies. The paper is published in the journal Nature Nanotechnology.
When a stone is dropped into water, circular waves spread outward from the point of impact. Light behaves similarly: When emitted from a localized source, it naturally propagates as spherical or circular wavefronts within a material. While this isotropic propagation is a fundamental property of waves, it is often undesirable in photonic applications where light must be guided efficiently along predefined paths.
Conventional optical technologies overcome this challenge using waveguides. In optical fiber communications, for example, glass fibers confine laser light and transport it over long distances with minimal loss. Similarly, photonic integrated circuits rely on nanoscale waveguides fabricated through complex lithographic processes, including resist coating, lithography and etching. These fabrication steps are technologically demanding and contribute significantly to manufacturing costs.