Lifeboat Foundation

In quantum physics, Fermi’s golden rule, also known as the golden rule of time-dependent perturbation theory, is a formula that can be used to calculate the rate at which an initial quantum state transitions into a final state, which is composed of a continuum of states (a so-called “bath”). This valuable equation has been applied to numerous physics problems, particularly those for which it is important to consider how systems respond to imposed perturbations and settle into stationary states over time.

Fermi’s golden rule specifically applies to instances in which an initial quantum state is weakly coupled to a continuum of other final states, which overlap its energy. Researchers at the Centro Brasileiro de Pesquisas Físicas, Princeton University, and Universität zu Köln have recently set out to investigate what happens when a quantum state is instead coupled to a set of discrete final states with a nonzero mean level spacing, as observed in recent many-body physics studies.

“The decay of a quantum state into some continuum of final states (i.e., a ‘bath’) is commonly associated with incoherent decay processes, as described by Fermi’s golden rule,” Tobias Micklitz, one of the researchers who carried out the study, told Phys.org. “A standard example for this is an excited atom emitting a photon into an infinite vacuum. Current date experimentations, on the other hand, routinely realize composite systems involving quantum states coupled to effectively finite size reservoirs that are composed of discrete sets of final states, rather than a continuum.”

Given the rapid pace at which technology is developing, it comes as no surprise that quantum technologies will become commonplace within decades. A big part of ushering in this new age of quantum computing requires a new understanding of both classical and quantum information and how the two can be related to each other.

Before one can send classical information across quantum channels, it needs to be encoded first. This encoding is done by means of quantum ensembles. A quantum ensemble refers to a set of quantum states, each with its own probability. To accurately receive the transmitted information, the receiver has to repeatedly ‘guess’ the state of the information being sent. This constitutes a cost function that is called ‘guesswork.’ Guesswork refers to the average number of guesses required to correctly guess the state.

The concept of guesswork has been studied at length in classical ensembles, but the subject is still new for quantum ensembles. Recently, a research team from Japan—consisting of Prof. Takeshi Koshiba of Waseda University, Michele Dall’Arno from Waseda University and Kyoto University, and Prof. Francesco Buscemi from Nagoya University—has derived analytical solutions to the guesswork problem subject to a finite set of conditions. “The guesswork problem is fundamental in many scientific areas in which machine learning techniques or artificial intelligence are used. Our results trailblaze an algorithmic aspect of the guesswork problem,” says Koshiba. Their findings are published in IEEE Transactions on Information Theory.

An experiment involving a Fibonacci pattern of laser pulses apparently yielded a new state of matter.

Try out my quantum mechanics course (and many others on math and science) on https://brilliant.org/sabine. You can get started for free, and the first 200 will get 20% off the annual premium subscription.

Welcome everybody to our first episode of Science News without the gobbledygook. Today we’ll talk about this year’s Nobel Prize in Physics, trouble with the new data from the Webb telescope, what’s next after NASA’s collision with an asteroid, new studies about the environmental impact of Bitcoin and exposure to smoke from wildfires, a test run of a new electric airplane, and dogs that can smell mathematics.

Continue reading “What’s next after NASA’s asteroid crash? A New Study on the Environmental Impact of Bitcoin & more” »

Quantum physics is strange. At least, it is strange to us, because the rules of the quantum world, which govern the way the world works at the level of atoms and subatomic particles (the behavior of light and matter, as the renowned physicist Richard Feynman put it), are not the rules that we are familiar with — the rules of what we call “common sense.”

The quantum rules, which were mostly established by the end of the 1920s, seem to be telling us that a cat can be both alive and dead at the same time, while a particle can be in two places at once. But to the great distress of many physicists, let alone ordinary mortals, nobody (then or since) has been able to come up with a common-sense explanation of what is going on. More thoughtful physicists have sought solace in other ways, to be sure, namely coming up with a variety of more or less desperate remedies to “explain” what is going on in the quantum world.

These remedies, the quanta of solace, are called “interpretations.” At the level of the equations, none of these interpretations is better than any other, although the interpreters and their followers will each tell you that their own favored interpretation is the one true faith, and all those who follow other faiths are heretics. On the other hand, none of the interpretations is worse than any of the others, mathematically speaking. Most probably, this means that we are missing something. One day, a glorious new description of the world may be discovered that makes all the same predictions as present-day quantum theory, but also makes sense. Well, at least we can hope.

Researchers have demonstrated a quantum sensor that can power itself using sunlight and an ambient magnetic field, an achievement that could help reduce the energy costs of this energy-hungry technology.

No longer the realm of science fiction, quantum sensors are today used in applications ranging from timekeeping and gravitational-wave detection to nanoscale magnetometry [1]. When making new quantum sensors, most researchers focus on creating devices that are as precise as possible, which typically requires using advanced—energy-hungry—technologies. This high energy consumption can be problematic for sensors designed for use in remote locations on Earth, in space, or in Internet-of-Things sensors that are not connected to mains electricity. To reduce the reliance of quantum sensors on external energy sources, Yunbin Zhu of the University of Science and Technology of China and colleagues now demonstrate a quantum sensor that directly exploits renewable energy sources to get the energy it needs to operate [2].

Quantum effects play a hitherto unexpected role in creating instabilities in DNA – the so-called “molecule of life” that provides instructions for cellular processes in all living organisms. This conclusion, based on work by researchers at the University of Surrey in the UK, goes against long-held beliefs that quantum behaviour is not relevant in the wet, warm environment of cells, and could have far-reaching consequences for models of genetic mutation.

The two strands of the DNA double helix are linked together by hydrogen bonds between the DNA bases. There are typically four different bases, called Guanine (G), Cytosine ©, Adenine (A) and Thymine (T). In the standard configuration, A always bonds to T while C always bonds to G. However, if the protons (nuclei of the hydrogen atoms) that make up the bonds hop from one strand of DNA to the other then a genetic mutation can occur.

\r \r

Physicists are (temporarily) augmenting reality in order to crack the code of quantum systems.

Calculating the collective behavior of a molecule’s electrons is necessary to predict a material’s properties. Such predictions could one day help scientists create novel drugs or create materials with desirable qualities like superconductivity. The issue is that electrons may become ‘quantum mechanically’ entangled with one another, which means they can no longer be treated individually. For any system with more than a few particles, the entangled network of connections becomes outrageously difficult for even the most powerful computers to unravel directly.

Now, quantum physicists from the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland and the Flatiron Institute’s Center for Computational Quantum Physics (CCQ) in New York City have found a workaround. By adding extra “ghost” electrons in their computations that interact with the system’s actual electrons, they were able to simulate entanglement.