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Category: particle physics – Page 555

The history of the universe is predicated on the idea that, compared to today, the universe was hotter and more symmetric in its early phase. Scientists have thought this because of the Higgs Boson finding—the particle that gives mass to all other fundamental particles. The concept is that as one analyzes time back toward the Big Bang, the universe gets hotter and the Higgs phase changes to one where everything became massless. Now, physicists are presenting a new theory that suggests an alternative history of the universe is possible.

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Possible quantum computing at room temperature. Scientists working with hexagonal boron nitride, which allows them to work in two-dimensional arrays. Simpler than using 3D objects such as diamonds.

Researchers have now demonstrated a new hardware platform based on isolated electron spins in a two-dimensional material. The electrons are trapped by defects in sheets of hexagonal boron nitride, a one-atom-thick semiconductor material, and the researchers were able to optically detect the system’s quantum states.

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Quantum physics sets the laws that dominate the universe at a small scale. The ability to harness quantum phenomena could lead to machines like quantum computers, which are predicted to perform certain calculations much faster than conventional computers. One major problem with building quantum processors is that the tracking and controlling quantum systems in real time is a difficult task because quantum systems are overwhelmingly fragile: Manipulating these systems carelessly introduces significant errors in the final result. New work by a team at Aalto could lead to precise quantum computers.

The researchers report controlling in a custom-designed electrical circuit called a transmon. Chilling a transmon chip to within a few thousandths of a degree above absolute zero induces a , and the chip starts to behave like an artificial atom. One of the features that interests researchers is that the of the transmon can only take specific values, called . The energy levels are like steps on a ladder: A person climbing the ladder must occupy a step, and can’t hover somewhere between two steps. Likewise, the transmon energy can only occupy the set values of the energy levels. Shining microwaves on the circuit induces the transmon to absorb the energy and climb up the rungs of the ladder.

In work published 8 February in the journal Science Advances, the group from Aalto University led by Docent Sorin Paraoanu, senior university lecturer in the Department of Applied Physics, has made the transmon jump more than one energy level in a single go. Previously, this has been possible only by very gentle and slow adjustments of the microwave signals that control the device. In the new work, an additional microwave control signal shaped in a very specific way allows a fast, precise change of the energy level. Dr. Antti Vepsäläinen, the lead author, says, “We have a saying in Finland: ‘hiljaa hyvää tulee’ (slowly does it). But we managed to show that by continuously correcting the state of the system, we can drive this process more rapidly and at .”

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Circa 2018

Researchers have demonstrated nanomaterial-based white-light-emitting diodes (LEDs) that exhibit a record luminous efficiency of 105 lumens per watt. Luminous efficiency is a measure of how well a light source uses power to generate light. With further development, the new LEDs could reach efficiencies over 200 lumens per watt, making them a promising energy-efficient lighting source for homes, offices and televisions.

“Efficient LEDs have strong potential for saving energy and protecting the environment,” said research leader Sedat Nizamoglu, Koç University, Turkey. “Replacing conventional lighting sources with LEDs with an of 200 lumens per watt would decrease the global electricity consumed for lighting by more than half. That reduction is equal to the electricity created by 230 typical 500-megawatt coal plants and would reduce greenhouse gas emissions by 200 million tons.”

The researchers describe how they created the high-efficiency white LEDs in Optica, The Optica l Society’s journal for high impact research. The new LEDs use commercially available blue LEDs combined with flexible lenses filled with a solution of nano-sized semiconductor particles called . Light from the blue LED causes the dots to emit green and red, which combines with the blue emission to create .

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A major threat to America has been largely ignored by those who could prevent it. An electromagnetic pulse (EMP) attack could wreak havoc on the nation’s electronic systems-shutting down power grids, sources, and supply mechanisms. An EMP attack on the United States could irreparably cripple the country. It could simultaneously inflict large-scale damage and critically limit our recovery abilities. Congress and the new Administration must recognize the significance of the EMP threat and take the necessary steps to protect against it.

Systems Gone Haywire

An EMP is a high-intensity burst of electromagnetic energy caused by the rapid acceleration of charged particles. In an attack, these particles interact and send electrical systems into chaos in three ways: First, the electromagnetic shock disrupts electronics, such as sensors, communications systems, protective systems, computers, and other similar devices. The second component has a slightly smaller range and is similar in effect to lightning. Although protective measures have long been established for lightning strikes, the potential for damage to critical infrastructure from this component exists because it rapidly follows and compounds the first component. The final component is slower than the previous two, but has a longer duration. It is a pulse that flows through electricity transmission lines-damaging distribution centers and fusing power lines. The combination of the three components can easily cause irreversible damage to many electronic systems.

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What actually occurs in a superposition—the strange condition in which entities seem to be in two or more places or states at the same? This is the root question in quantum mechanics, and the answer was unknown until now. In a new research paper, a joint team of researchers from Israel and Japan, has described a novel experiment that could finally shed light on the true nature of this puzzling phenomenon.

The researchers estimate that their experiment, that can be carried out within a few months, could possibly allow scientists a sneak peek at where an object like a particle of light i.e. a photon will actually be when it is positioned in a superposition. And as per their predictions, the answer can be even stranger and more baffling than “two places at once.”

The characteristic occurrence of a superposition involves firing photons at two parallel slits into a barrier. One fundamental aspect of quantum mechanics is that the tiny particles can behave like waves, so that those passing through one slit “interfere” with those passing through the other. These wavy ripples either boost or cancel one another to create a new characteristic pattern on a detector screen. The oddest fact is that this interference occurs even if only a single particle is fired at a time. The particle seems to somehow pass through both slits simultaneously and displays interference with itself. This is a true superposition.

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