Lifeboat Foundation

Circa 2018

The symmetries that govern the world of elementary particles at the most elementary level could be radically different from what has so far been thought. This surprising conclusion emerges from new work published by theoreticians from Warsaw and Potsdam. The scheme they posit unifies all the forces of nature in a way that is consistent with existing observations and anticipates the existence of new particles with unusual properties, which may even be present in our close environs.

For half a century, physicists have been trying to construct a theory that brings together all four fundamental forces of nature, describes the known elementary particles and predicts the existence of new ones. So far these attempts have not found experimental confirmation and the Standard Model — an old and surely incomplete, but still surprisingly effective theoretical construct — has successfully remained in use for years as our best description of the quantum world. In a recent paper in Physical Review Letters, Prof. Krzysztof Meissner from the Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, and Prof. Hermann Nicolai from the Max-Planck-Institut für Gravitationsphysik in Potsdam have presented a new scheme generalizing the Standard Model that incorporates gravitation into the description. The shortcomings of previous attempts were overcome through the application of a kind of symmetry not previously used in the description of elementary particles.

In physics, symmetries are understood somewhat differently than in the colloquial sense of the word. For instance, note that whether we drop a ball from the same spot now or one minute from now, it will still fall in the same way. That is a manifestation of a certain symmetry: the laws of physics remain unchanged with respect to shifts in time. Similarly, we can drop the ball while standing and facing once in a southward direction, once westward, or we can drop it from the same height in one location, then another. The ball will still fall in the same way in both cases, which means that the laws of physics are symmetrical also with respect to the operations of rotation and spatial displacement, respectively.

A team of scientists, led by the University of Bristol, have discovered a new method that could be used to build quantum sensors with ultra-high precision.

When individual atoms emit light, they do so in discrete packets called photons.

When this light is measured, this discrete or ‘granular’ nature leads to especially low fluctuations in its brightness, as two or more photons are never emitted at the same time.

A ground-breaking study conducted by researchers from the National University of Singapore (NUS) has revealed a method of using quantum mechanical wave theories to “lock” heat into a fixed position.

Ordinarily, a source of heat diffuses through a conductive material until it dissipates, but Associate Professor Cheng-Wei Qiu from the Department of Electrical and Computer Engineering at the NUS Faculty of Engineering and his team used the principle of anti-parity-time (APT) symmetry to show that it is possible to confine the heat to a small region of a metal ring without it spreading over time.

In the future, this newly demonstrated phenomenon could be used to control heat diffusion in sophisticated ways and optimize efficacy in systems that need cooling. The results of the study were published on 12 April 2019 in the journal Science.

Mikel Sanz, of the Physical Chemistry Department of UPV/EHU, leads the theoretical group for an experiment published by the prestigious journal, Nature Communications. The experiment has managed to prepare a remote quantum state; i.e., absolutely secure communication was established with another, physically separated quantum computer for the first time in the microwave regime. This new technology may bring about a revolution in the next few years.

Within the greater European project of the Quantum Flagship, spearheaded by Mikel Sanz—researcher of the QUTIS Group of the UPV/EHU Physical Chemistry Department—an experiment has been conducted in collaboration with German and Japanese researchers who have managed to develop a protocol for preparing a remote quantum state while conducting communication in the microwave regime, “which is the frequency at which all quantum computers operate. This is the first time the possibility of doing so in this range has been examined, which may bring about a revolution in the next few years in the field of secure quantum communication and quantum microwave radars,” lead researcher in this project Mikel Sanz observes.

The preparation of a remote quantum state (known as remote state preparation) is based on the phenomenon of quantum entanglement, where sets of entangled particles lose their individuality and behave as single entities, even when spatially separated. “Thus, if two computers share this quantum correlation, performing operations on only one of them can affect the other. Absolutely secure communication can be achieved,” Sanz explains.

Move aside, electrons; it’s time to make way for the trion.

A research team led by physicists at the University of California, Riverside, has observed, characterized, and controlled dark trions in a semiconductor—ultraclean single-layer tungsten diselenide (WSe₂)—a feat that could increase the capacity and alter the form of information transmission.

In a semiconductor, such as WSe₂, a trion is a quantum bound state of three charged particles. A negative trion contains two electrons and one hole; a positive trion contains two holes and one electron. A hole is the vacancy of an electron in a semiconductor, which behaves like a positively charged particle. Because a trion contains three interacting particles, it can carry much more information than a single electron.

Physicists at the University of Innsbruck are proposing a new model that could demonstrate the supremacy of quantum computers over classical supercomputers in solving optimization problems. In a recent paper, they demonstrate that just a few quantum particles would be sufficient to solve the mathematically difficult N-queens problem in chess even for large chess boards.

Even in the strange world of open quantum systems, the arrow of time points steadily forward—most of the time. New experiments conducted at Washington University in St. Louis compare the forward and reverse trajectories of superconducting circuits called qubits, and find that they follow the second law of thermodynamics. The research is published July 9 in the journal Physical Review Letters.

“When you look at a quantum system, the act of measuring usually changes the way it behaves,” said Kater Murch, associate professor of physics in Arts & Sciences. “Imagine shining light on a small particle. The photons end up pushing it around and there is a dynamic associated with the measurement process alone.

Continue reading “Characterizing the ‘arrow of time’ in open quantum systems” »

The quantum computing revolution is upon us.

Establish a foundation of knowledge for understanding quantum computing with this two-course online program. Starts October 7th, 2019.

If scientists could find a way to control the process for making semiconductor components on a nanometric scale, they could give those components unique electronic and optical properties—opening the door to a host of useful applications.

Researchers at the Laboratory of Microsystems, in EPFL’s School of Engineering, have taken an important step towards that goal with their discovery of semiconducting nanotubes that assemble automatically in solutions of metallic nanocrystals and certain ligands. The tubes have between three and six walls that are perfectly uniform and just a few atoms thick—making them the first such nanostructures of their kind.

What’s more, the nanotubes possess photoluminescent properties: they can absorb light of a specific wavelength and then send out intense light waves of a different color, much like quantum dots and quantum wells. That means they can be used as fluorescent markers in medical research, for example, or as catalysts in photoreduction reactions, as evidenced by the removal of the colors of some organic dyes, based on the results of initial experiments. The researchers’ findings have made the cover of ACS Central Science.