Physics

Like navigating spacecraft through the solar system by means of gravity and small propulsive bursts, researchers can guide atoms, molecules and chemical reactions by utilizing the forces that bind nuclei and electrons into molecules (analogous to gravity) and by using light for propulsion. But, knowing the minimal amount of light required, and how that amount changes with the complexity of the molecule, has been a problem.

Now, by creating a quantum mechanical analog of Ulam’s conjecture, researchers at the University of Illinois and the University of California have expanded the flexibility and controllability of quantum mechanical systems.

The dream of theoretical physics is to unite behind a common theory that explains everything, but that goal has remained highly elusive.

String theory emerged 40 years ago as one of the most promising candidates for such a theory, and has since slipped in and out of favor as new innovations have occurred. Now Europe is fortunate to have one of the world’s leading experts in string theory working on an ambitious project that could make significant progress towards a unified theory, and at least help resolve two mysteries.

One is how the universe emerged in the beginning as a random fluctuation of a vacuum state, and the other is a common explanation for all sub-atomic particles.

An international research team, led by scientists at the London Centre for Nanotechnology (LCN), has found a way to switch a material’s magnetic properties from ‘hard’ to ‘soft’ and back again – something which could lead to new ways of controlling electromagnetic devices. The research shows how a magnet can be ‘tuned’ by subjecting it to a second magnetic field, perpendicular to the original.

Magnets can be classified by their ‘hard’ or ‘soft’ magnetic properties. Hard magnets, sometimes called ‘permanent’ magnets, have fixed or ‘pinned’ domain walls which mean the material stays magnetised for a long time. Soft magnets have moveable domain walls that can be easily flipped.

An international team of scientists, including several at The Johns Hopkins University, has detected a hidden magnetic “quantum order” that extends over chains of nearly 100 atoms in a material that is otherwise magnetically disordered.

The findings, which are published online today (July 26) in the journal Science, may have implications for the design of devices and materials for quantum information processing, including large-scale quantum computers capable of tackling problems exponentially faster than can conventional computers.

The team’s results are important because they demonstrate that the magnetic moments (the measure of the strength of a magnetic source) of a large number of atoms can band together to form quantum states much like those of a very large molecule.

Physicists at the Commerce Department’s National Institute of Standards and Technology (NIST) have induced thousands of atoms trapped by laser beams to swap “spins” with partners simultaneously.

The repeated exchanges, like a quantum version of swinging your partner in a square dance but lasting a total of just 10 milliseconds, might someday carry out logic operations in quantum computers, which theoretically could quickly solve certain problems that today's best supercomputers could not solve in years.

The atomic dance advances prospects for the use of neutral atoms as quantum bits (qubits) for storing and processing data in quantum computers.

There are many objects in nature, such as flowers, that are “pre-programmed” to develop into delicate, beautiful and intrically shaped forms. But can this pre-determined process be duplicated by man starting with plain, flat surfaces?

Yes, say Dr. Eran Sharon and his co-workers, Yael Klein and Efi Efrati, at the Hebrew University of Jerusalem Racah Institute of Physics, who have succeded for the first time anywhere in programming polymer sheets to bend and wrinkle by themselves into prescribed structures. Their work was described in the journal Science.

They made flat discs of a soft gel that, when warmed gently, curved into domes, saddles and even sombrero shapes.

New fundamental particles aren’t found only at Fermilab and at other particle accelerators. They also can be found hiding in plain pieces of ceramic, scientists at the University of Illinois report.

The newly formulated particle is a boson and has a charge of 2e, but does not consist of two electrons, the scientists say. The particle arises from the strong, repulsive interactions between electrons, and provides another piece of the high-temperature superconductivity puzzle.

Twenty-one years ago, superconductivity at high temperatures was discovered in copper-oxide ceramics (cuprates).

Each time you press "save" on your computer you force atoms on magnets to align their polarity with the intruding magnetic field. Helping physicists understand why it happens and why it isn't a physics-induced train wreck more often is the goal of Joshua Deutsch and Andreas Berger and they say their research could advanced materials research.

Correcting even a single typo in an e-mail means changing dozens of bits of information. For each bit, a magnetic head grazes a tiny patch of your disk drive, forcing its polarity, or "spin," to align up or down--the magnetic equivalent of a one or a zero.

It may seem odd to think about using metallic structures for transmitting light because light quickly attenuates on passing through a metal, but light waves travelling only a few centimeters don't lose their energy and that discover could change the face of nanotechnology.

The discovery, known as acoustic plasmon, are surface plasmons formed by the group excitation of electrons but it is produced by the interaction between light and metal surfaces.

The advantage of acoustic plasmons over the long-known surface plasmons is that they are created with a different amount of energy.

A research team headed by Yadong Yin at the University of California, Riverside has created a liquid that changes its color “on demand” and can take on any color of the rainbow.

Nanoscopic particles made of tiny magnetic crystals coated with a plastic shell self-assemble in solution to form photonic crystals—semiconductors for light. When a magnetic field is applied, the optical properties of the crystals change, allowing their color to be very precisely adjusted through variation of the strength of the field.

The crystals involved are not “conventional” lattices of ions or molecules like the ones for salt. They are colloidal crystals, periodic structures that form from uniform solid particles that are finely dispersed in a liquid.