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Lenses are used to bend and focus light. Normal lenses rely on their curved shape to achieve this effect, but physicists from the University of Amsterdam and Stanford University have made a flat lens of only three atoms thick which relies on quantum effects. This type of lens could be used in future augmented reality glasses.

The findings have been published in Nano Letters (“Temperature-Dependent Excitonic Light Manipulation with Atomically Thin Optical Elements”).

The thinnest lens on Earth, made of concentric rings of tungsten disulphide (WS2), uses excitons to efficiently focus light. The lens is as thick as a single layer of WS2, just three atoms thick. The bottom left shows an exciton: an excited electron bound to the positively charged ‘hole’ in the atomic lattice. (Image: Ludovica Guarneri and Thomas Bauer)

A new method developed by Amsterdam researchers uses non-Gaussian states to efficiently describe and configure quantum spin-boson systems, promising advancements in quantum computing and sensing.

Many modern quantum devices operate using groups of qubits, or spins, which have just two energy states: ‘0’ and ‘1’. However, in actual devices, these spins also interact with photons and phonons, collectively known as bosons, making the calculations much more complex. In a recent study published in Physical Review Letters, researchers from Amsterdam have developed a method to effectively describe these spin-boson systems. This breakthrough could help in efficiently setting up quantum devices to achieve specific desired states.

Quantum devices use the quirky behavior of quantum particles to perform tasks that go beyond what ‘classical’ machines can do, including quantum computing, simulation, sensing, communication, and metrology. These devices can take many forms, such as a collection of superconducting circuits, or a lattice of atoms or ions held in place by lasers or electric fields.

Time loops have long been the stuff of science fiction. Now, using the rules of quantum mechanics, we have a way to effectively transport a particle back in time – here’s how.

By Miriam Frankel

Year 2023 face_with_colon_three

A team led by researchers at Osaka University and University of California, San Diego has conducted simulations of creating matter solely from collisions of light particles. Their method circumvents what would otherwise be the intensity limitations of modern lasers and can be readily implemented by using presently available technology. This work might help experimentally test long-standing theories such as the Standard Model of particle physics, and possibly the need to revise them.

One of the most striking predictions of quantum physics is that matter can be generated solely from light (i.e., photons), and in fact, the astronomical bodies known as pulsars achieve this feat. Directly generating matter in this manner has not been achieved in a laboratory, but it would enable further testing of the theories of basic quantum physics and the fundamental composition of the universe.

Continue reading “Let there be matter: Simulating the creation of matter from photon–photon collisions” »

The team spent years perfecting an intricate process for manufacturing two-dimensional arrays of atom-sized qubit microchiplets and transferring thousands of them onto a carefully prepared complementary metal-oxide semiconductor (CMOS) chip. This transfer can be performed in a single step.

“We will need a large number of qubits, and great control over them, to really leverage the power of a quantum system and make it useful. We are proposing a brand new architecture and a fabrication technology that can support the scalability requirements of a hardware system for a quantum computer,” says Linsen Li, an electrical engineering and computer science (EECS) graduate student and lead author of a paper on this architecture.

Microscopic chinks in material just several atoms thick have the potential to advance a multitude of quantum technologies, new research shows – getting us closer to the widespread use of quantum networks and sensors.

Right now, storing quantum data in the spin properties of electrons, known as spin coherence, requires a very particular and delicate laboratory setup. It’s not something you can do without a carefully controlled environment.

Here, an international team of researchers managed to demonstrate observable spin coherence at room temperature, using the tiny defects in a layered 2D material called Hexagonal Boron Nitride (hBN).

Materials scientists and engineers would like to know precisely how electrons interact and move in new materials and how the devices made with them will behave. Will the electrical current flow easily within the material? Is there a temperature at which the material will become superconducting, enabling current to flow without a power source? How long will the quantum state of an electron spin be preserved in new electronic and quantum devices?

Ask anyone working in quantum computing and they may tell you they have been dealing with the frustratingly contrarian and intricately delicate state of entanglement since the beginning of time. However, a new study suggests this might be impossible. In fact, entanglement may have been absent in the earliest moments of the universe, researchers are reporting — a hypothesis that would — if validated — challenge our understanding of quantum mechanics and the nature of time itself.

The research, detailed in a paper by Jim Al-Khalili, of the University of Surrey and Eddy Keming Chen, University of California, San Diego and published on the pre-print server ArXiv, explores the so-called entanglement past hypothesis. In the study, the researchers explore why time only flows in one direction, a fundamental concept in both quantum physics and thermodynamics.

According to the researchers the concept of quantum entanglement, where two particles become so deeply linked that their properties seem to remain interconnected regardless of the distance between them, is central to modern quantum mechanics. It’s also a key ingredient for the potential of quantum computers to tackle massively complex calculations. It’s also why quantum computing is so vexing, because entanglement can be disrupted by external influences, leading to a process known as decoherence.

Quantum emitters in Si show promise for applications in quantum information processing and communication due to their potential as spin-photon interfaces. Jhuria et al. report the formation of selected telecom emitters in Si using local writing and erasing by fs laser pulses and annealing in a hydrogen atmosphere.