A breakthrough in quantum computing could expose every communications link. The same breakthrough could make everything secure again. What could change everything are all the events in-between.
Why can atoms or elementary particles behave like waves according to quantum physics, which allows them to be in several places at the same time? And why does everything we see around us obviously obey the laws of classical physics, where that is impossible? To answer those questions, in recent years researchers have coaxed larger and larger objects into behaving quantum mechanically. One consequence of this is that, when passing through a double slit, they form an interference pattern that is characteristic of waves.
Up to now this could be achieved with molecules consisting of a few thousand atoms. However, physicists hope one day to be able to observe such quantum effects with properly macroscopic objects. Lukas Novotny, Professor of Photonics, and his collaborators at the Department of Information Technology and Electrical Engineering at ETH Zurich have now made a crucial step in that direction. Their results were recently published in the scientific journal Nature.
Researchers at ETH Zurich have trapped a tiny sphere measuring a hundred nanometres using laser light and slowed down its motion to the lowest quantum mechanical state. Based on this, one can study quantum effects in macroscopic objects and build extremely sensitive sensors.
Many of us swing through gates every day—points of entry and exit to a space like a garden, park or subway. Electronics have gates too. These control the flow of information from one place to another by means of an electrical signal. Unlike a garden gate, these gates require control of their opening and closing many times faster than the blink of an eye.
Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and the University of Chicago’s Pritzker School of Molecular Engineering have devised a unique means of achieving effective gate operation with a form of information processing called electromagnonics. Their pivotal discovery allows real-time control of information transfer between microwave photons and magnons. And it could result in a new generation of classical electronic and quantum signal devices that can be used in various applications such as signal switching, low-power computing and quantum networking.
Microwave photons are elementary particles forming the electromagnetic waves employed in, for example, wireless communications. Magnons are the particle-like representatives of “spin waves.” That is, wave-like disturbances in an ordered array of microscopically aligned spins that occur in certain magnetic materials.
Researchers have found evidence for an anomalous phase of matter that was predicted to exist in the 1960s. Harnessing its properties could pave the way to new technologies able to share information without energy losses. These results are reported in the journal Science Advances.
While investigating a quantum material, the researchers from the University of Cambridge who led the study observed the presence of unexpectedly fast waves of energy rippling through the material when they exposed it to short and intense laser pulses. They were able to make these observations by using a microscopic speed camera that can track small and very fast movement on a scale that is challenging with many other techniques. This technique probes the material with two light pulses: the first one disturbs it and creates waves—or oscillations—propagating outward in concentric circles, in the same way as dropping a rock into a pond; the second light pulse takes a snapshot of these waves at various times. Put together, these images allowed them to look at how these waves behave, and to understand their ‘speed limit.’
“At room temperature, these waves move at a hundredth of the speed of light, much faster than we would expect in a normal material. But when we go to higher temperatures, it is as if the pond has frozen,” explained first author Hope Bretscher, who carried out this research at Cambridge’s Cavendish Laboratory. “We don’t see these waves moving away from the rock at all. We spent a long time searching for why such bizarre behavior could occur.”
Researchers have found a way to enhance radiation therapy using novel iodine nanoparticles.
Cancer cell death is triggered within three days when X-rays are shone onto tumor tissue containing iodine-carrying nanoparticles. The iodine releases electrons that break the tumor’s DNA, leading to cell death. The findings, by scientists at Kyoto University’s Institute for Integrated Cell-Material Sciences (iCeMS) and colleagues in Japan and the US, were published in the journal Scientific Reports.
“Exposing a metal to light leads to the release of electrons, a phenomenon called the photoelectric effect. An explanation of this phenomenon by Albert Einstein in 1905 heralded the birth of quantum physics,” says iCeMS molecular biologist Fuyuhiko Tamanoi, who led the study. “Our research provides evidence that suggests it is possible to reproduce this effect inside cancer cells.”
A tachyon field might be responsible for cosmological inflation at an early time and contribute to cosmological dark matter at a later time. We investigate tachyonic inflation by analyzing a tachyon field with different potentials in the framework of loop quantum cosmology. No matter which tachyon field energy dominates at the bounce, the evolution of the background can be divided into three phases: super-inflation, damping, and slow-roll inflation. The duration of each phase depends on the initial condition. During the slow-roll inflation, when the initial condition is $$V(T_\mathrm{B})/\rho _\mathrm{c}\ge 10^{-6}$$ V(TB)/ρc≥10–6, the number of e-folds is very high ($$N\gg 60$$ N≫60) for $$V\propto T^{-n}$$ V∝T-n with $$n=1$$ n=1 and 1 / 2. For an exponential potential, to get enough e-folds, $$V(T_\mathrm{B})/\rho _\mathrm{c}$$ V(TB)/ρc should be greater than $$7.802\times 10^{-4}$$7.
Scientists from the Division of Physics at the University of Tsukuba used the quantum effect called ‘spin-locking’ to significantly enhance the resolution when performing radio-frequency imaging of nitrogen-vacancy defects in diamond. This work may lead to faster and more accurate material analysis, as well as a path towards practical quantum computers.
Nitrogen-vacancy (NV) centers have long been studied for their potential use in quantum computers. A NV center is a type of defect in the lattice of a diamond, in which two adjacent carbon atoms have been replaced with a nitrogen atom and a void. This leaves an unpaired electron, which can be detected using radio-frequency waves, because its probability of emitting a photon depends on its spin state. However, the spatial resolution of radio wave detection using conventional radio-frequency techniques has remained less than optimal.
Now, researchers at the University of Tsukuba have pushed the resolution to its limit by employing a technique called ‘spin-locking’. Microwave pulses are used to put the electron’s spin in a quantum superposition of up and down simultaneously. Then, a driving electromagnetic field causes the direction of the spin to precess around, like a wobbling top. The end result is an electron spin that is shielded from random noise but strongly coupled to the detection equipment. “Spin-locking ensures high accuracy and sensitivity of the electromagnetic field imaging,” first author Professor Shintaro Nomura explains. Due to the high density of NV centers in the diamond samples used, the collective signal they produced could be easily picked up with this method. This permitted the sensing of collections of NV centers at the micrometer scale.
Basically means that time travel would be tricky as the reality bubble could collapse. One would need to strengthen the reality so that the past would still be the past and future the future.
It was first suggested by David Z. Albert that the existence of a real, physical non-unitary process (i.e., “collapse”) at the quantum level would yield a complete explanation for the Second Law of Thermodynamics (i.e., the increase in entropy over time). The contribution of such a process would be to provide a physical basis for the ontological indeterminacy needed to derive the irreversible Second Law against a backdrop of otherwise reversible, deterministic physical laws. An alternative understanding of the source of this possible quantum “collapse” or non-unitarity is presented herein, in terms of the Transactional Interpretation (TI).
😀 2011
Trevor D. Rhone, Dwipesh Majumder, Brian S. Dennis, Cyrus Hirjibehedin, Irene Dujovne, Javier G. Groshaus, Yann Gallais, Jainendra K. Jain, Sudhansu S. Mandal, Aron Pinczuk, Loren Pfeiffer, and Ken West. 2011. “Higher-Energy Composite Fermion Levels in the Fractional Quantum Hall Effect.” Phys. Rev. Lett., 106, Pp. 096803.
