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Category: quantum physics – Page 578

Annihilation of exceptional points from various degeneration points observed for the first time

A team of researchers from the University of Warsaw in Poland, the Institute Pascal CNRS in France, the Military University of Technology in Poland and the British University of Southampton has shown that it is possible to control the so-called exceptional points. For the first time, physicists also observed the annihilation of exceptional points from different degeneracy points. You can read about the discovery that may contribute to the creation of modern optical devices in the latest Nature Communications.

The universe around us is made of , most of which have their antiparticles. When a particle and an antiparticle, that is, matter and antimatter, meet each other, annihilation occurs. Physicists have long been able to produce quasiparticles and quasiantiparticles—elementary excitations: charge, vibration, energy—trapped in matter, most often in crystals or liquids.

“The world of quasiparticles can be very complicated, although paradoxically, the quasiparticles themselves help simplify the description of quantum phenomena,” explains Jacek Szczytko from the Faculty of Physics at the University of Warsaw.

Fluctuation relations for irreversible emergence of information

Information variations in a chain-like system are associated to energy transactions with the environment, which can take place reversibly or irreversibly, with a lower theoretical energy limit22,23. Fluctuations as a consequence of pure computations are on the order of the thermal level (i.e., similar to kT, being k the Boltzmann constant and T the absolute temperature), according to Landauer’s principle. Such energies are negligible at routine human scales but become significant when the size of the system is nanoscopic or smaller, because the work and heat it generates also compare with the thermal level. Small systems are based on nanostructures, including individual molecules and arrangements of atoms, such as biological and quantum systems.

Fluctuation theorems have appeared in recent years explaining quantitatively energy imbalances between forward and reverse pathways or between equilibrium and non-equilibrium processes24,25. They have been tested experimentally26,27,28, mostly in biomolecular systems analyzed on a one-by-one basis29. Most of these theorems establish relations among thermodynamic potentials for general systems, often with no specific insight into information theory. This theory, in turn, deals with spatially-indexed, 1-dimensional arrangements of symbols, which may not be necessarily associated to a time order. Recent generalizations separate the role of information and feedback control30,31, but still the interpretation of non-Markovianity, irreversibility and reversibility in terms of purely informational operations such as reading, writing and error correction32,33 remains obscured.

Here, we analyze energy exchanges associated to the symbolic management of a sequence of characters, without reference to the physical construction of the chain. Just by considering reversibility at the single sequence level and conservation laws, we next present two pairs of fluctuations equalities in the creation of information sequences, which use depends on energy exchange constraints. Our analysis integrates key information concepts, namely, reading, writing, proof reading and editing in the thermodynamic description of a string of symbols with information.

The origin of our universe from the multiverse — with Laura Mersini-Houghton

Join cosmologist Laura Mersini-Houghton as she discusses her ground-breaking theory, and how her path from communist Albania helped her become one of the most courageous thinkers on the world stage of theoretical physics. Watch the Q&A for this video here: https://youtu.be/6xpVP_ITEYE

Laura’s book “Before the Big Bang: The Origin of Our Universe from the Multiverse” is available to purchase now: https://geni.us/2TDDa.
Subscribe for regular science videos: http://bit.ly/RiSubscRibe.

The multiverse has gone from philosophical speculation to one of the most compelling and credible explanations of our universe’s origins.

In this talk, Laura interweaves her unconventional journey with reshaping our understanding of humanity’s places in the unfathomable vastness of the cosmos.

This lecture was filmed on 3 August 2022.

0:00 Introduction.

Continue reading “The origin of our universe from the multiverse — with Laura Mersini-Houghton” | >

Quantum camera snaps objects it cannot ‘see’

Circa 2008 0.0!

A normal digital camera can take snaps of objects not directly visible to its lens, US researchers have shown. The “ghost imaging” technique could help satellites take snapshots through clouds or smoke.

Physicists have known for more than a decade that ghost imaging is possible. But, until now, experiments had only imaged the holes in stencil-like masks, which limited its potential applications.

Now Yanhua Shih of the University of Maryland, Baltimore, and colleagues at the US Army Research Laboratory, also in Maryland, have now taken the first ghost images of an opaque object – a toy soldier (see image, top right).

Chaos theory eliminates quantum uncertainty

Two of the key founders of quantum physics, Einstein and Schrödinger, were deeply sceptical of its implications about uncertainty and the nature of reality. Today, the orthodox reading is that uncertainty is indeed an inherent feature of quantum systems, not a reflection of our own lack of knowledge. But Oxford physicist Tim Palmer now argues that chaos theory shows that quantum uncertainty is in fact down to our own ignorance, not reality itself. This could have far-reaching consequences for our ability to marry quantum mechanics with general relativity.

New measurements quantifying qudits provide glimpse of quantum future

Using existing experimental and computational resources, a multi-institutional team has developed an effective method for measuring high-dimensional qudits encoded in quantum frequency combs, which are a type of photon source, on a single optical chip.

Although the word “qudit” might look like a typo, this lesser-known cousin of the qubit, or , can carry more information and is more resistant to noise—both of which are key qualities needed to improve the performance of quantum networks, quantum key distribution systems and, eventually, the quantum internet.

Classical computer bits categorize data as ones or zeroes, whereas qubits can hold values of one, zero or both—simultaneously—owing to superposition, which is a phenomenon that allows multiple quantum states to exist at the same time. The “d” in qudit stands for the number of different levels or values that can be encoded on a photon. Traditional qubits have two levels, but adding more levels transforms them into qudits.

Research team develops a theory to improve the energy efficiency of electronic devices

The University of Alicante Quantum Chemistry group has predicted and published the existence of a new natural phenomenon in matter-radiation interaction, which has recently been experimentally confirmed. This finding is the subject of the review that the group’s researcher Juan Carlos Sancho García has submitted to the journal Nature, having been invited to publish in its “News & Views” section.

According to Sancho, his contribution is a successful example of how theory and simulation make it possible to advance and predict phenomena that are later confirmed by experiments, with the corresponding possible impact on the technological advances that populate society and the world today. In particular, the review reports the empirical confirmation of a prediction previously made and published by the UA team using quantum mechanics calculations. This is based on the effect of the “electronic correlation” that occurs strongly in this type of molecules studied, by which it is possible to take advantage of 100% of the energy that is emitted in the form of visible light on any screen.

The researcher explains that each of the pixels of a screen that makes up any device such as mobile phones, tablets, etc. is made up of molecules that emit the three basic colors (red, green, and blue). The battery activates these molecules to emit light () so that they first reach their maximum level of “excitation” and then decay, and it is this loss of energy that results in the emission of color.

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