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Category: particle physics

I never doubt the theory.

We owe a lot to Einstein, and this week physicists have confirmed another of his theories by unraveling and proving that quantum entanglement does in fact exist. Under the standard quantum theory, nothing has a definitive state until it’s measured, and when two particles interact they become entangled. Being entangled means no longer do the particles have their probabilities but one that includes both particles together. Even though two photons become entangled, they can still travel light years apart from each other, but they will always remain linked.

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In the past, traditional methods to understand the behavior of quantum interacting systems have worked well, but there are still many unsolved problems. To solve them, Giuseppe Carleo of ETH Zurich, Switzerland, used machine learning to form a variational approach to the quantum many-body problem.

Before digging deeper, let me tell you a little about the many-body problem. It deals with the difficulty of analyzing “multiple nontrivial relationships encoded in the exponential complexity of the many-body wave function.” In simpler language, it’s the study of interactions between many quantum particles.

If we take a look at our current computing power, modeling a wave function will need lot more powerful supercomputers. But, according to Carleo, the neural networks are pretty good at generalizing. Hence, they need only limited information to infer something. So, fiddling with this idea, Carleo and Matthias Troyer created a simple neural network to reconstruct such multi-body wave function.

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Quantum interpolation makes viewing Biomolecules at room temp. possible without freezing. This technique will enable more powerful sensors than we have ever had before.

In the latest issue of Proceedings of the National Academy of Sciences, researchers from MIT and Singapore University of Technology and Design are describing a new technique that may finally give life scientists a detailed view into many of the biomolecules they work with. These days, X-ray diffraction is typically used to see the structure of a molecule. But this requires crystallization, a process not all molecules, including many proteins, are unwilling to undergo.

The technology uses tiny diamond crystals that have a nitrogen atom in place of a single carbon atom. These so-called “nitrogen vacancy centers” make the crystals react to minute fluctuations of magnetic and electric fields surrounding them. They’re so sensitive that the spins of individual atoms of a nearby molecule affect them enough to be detected by an external device.

Using nitrogen vacancy centers is not new, but previously the resolution that was achieved has not been sufficient to accurately image most molecules. That is because microwaves were typically used to detect the state of the diamond crystals, and the way they’ve been used has led to limited results. The latest research relies on “quantum interpolation,” which in simplified terms means taking multiple readings of the magnetic field around the diamond crystals using different microwave pulses at the same time.

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Nice information on Quantum open systems via the existence of a functional relationship between a rigorous measure of quantum non–Markovian ity and the CCA localization. Sharing with my other QC R&D friends.

As discovered by P. W. Anderson, excitations do not propagate freely in a disordered lattice, but, due to destructive interference, they localise. As a consequence, when an atom interacts with a disordered lattice, one indeed observes a non-trivial excitation exchange between atom and lattice. Such non-trivial atomic dynamics will in general be characterised also by a non-trivial quantum information backflow, a clear signature of non–Markovian dynamics. To investigate the above scenario, we consider a quantum emitter, or atom, weakly coupled to a uniform coupled-cavity array (CCA). If initially excited, in the absence of disorder, the emitter undergoes a Markovian spontaneous emission by releasing all its excitation into the CCA (initially in its vacuum state). By introducing static disorder in the CCA the field normal modes become Anderson-localized, giving rise to a non–Markovian atomic dynamics. We show the existence of a functional relationship between a rigorous measure of quantum non–Markovian ity and the CCA localization. We furthermore show that the average non–Markovian ity of the atomic dynamics is well-described by a phenomenological model in which the atom is coupled, at the same time, to a single mode and to a standard — Markovian — dissipative bath.

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Members of the Faculty of Physics, the Lomonosov Moscow State University have elaborated a new technique for creation of entangled photon states, exhibiting photon pairs, which get correlated (interrelated) with each other. Scientists have described their research in an article, published in the journal Physical Review Letters.

Physicists from the Lomonosov Moscow State University have studied an entangled photon state, in which the state is determined only for the whole system and not for each separate particle.

Stanislav Straupe, Doctor of Sciences in Physics and Mathematics, a member of the Quantum Electronics Department and Quantum Optical Technologies Laboratory at the Faculty of Physics, the Lomonosov Moscow State University, and one of the article co-authors says the following. He explains: “Entangled states are typical and general. The only problem is in the point that for the majority of particles interaction with the environment destroys the entanglement. And photons hardly ever interact with other particles, thus they are a very convenient object for experiments in this sphere. The largest part of light sources we face in our life is a classical one — for instance, the Sun, stars, incandescent lamps and so on. Coherent laser radiation also belongs to the classical part. To create nonclassical light isn’t an easy thing. You could, for instance, isolate a single atom or an artificial structure like a quantum dot and detect its radiation – this is the way for single photons obtaining.”

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For the first time, researchers have synthesised a strange and unstable triangle-shaped molecule called triangulene, which physicists have been chasing for nearly 70 years.

Triangulene is similar to the ‘wonder material’ graphene in that it’s only one-atom-thick. But instead of sheet of carbon atoms, triangulene is made up of six hexagonal carbon molecules joined along their edges to form a triangle — an unusual arrangement that leaves two unpaired electrons unable form a stable bond. No one has ever been able to synthesise the molecule until now.

The elusive molecule was created by a team of researchers from IBM, using a needle-like microscope tip to manipulate individual atoms into the desired format.

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Nice.

Physicists at the University of Bonn have cleared a further hurdle on the path to creating quantum computers: in a recent study, they present a method with which they can very quickly and precisely sort large numbers of atoms. The work has now been published in Physical Review Letters.

Imagine you are standing in a grocery store buying apple juice. Unfortunately, all of the crates are half empty because other customers have removed individual bottles at random. So you carefully fill your crate bottle by bottle. But wait: The neighboring crate is filled in exactly the opposite way! It has bottles where your crate has gaps. If you could lift these bottles in one hit and place them in your crate, it would be full straight away. You could save yourself a lot of work.

Unfortunately, such solutions don’t (yet) exist for half-empty drinks crates. However, physicists at the University of Bonn want to sort thousands of atoms however they like in the future in this way — and in a matter of seconds. Around the world, scientists are currently looking for methods that enable sorting processes in the microcosm. The proposal by Bonn-based researchers could push the development of future quantum computers a crucial step forward. This allows atoms to interact with each other in a targeted manner in order to be able to exploit quantum-mechanical effects for calculations. In addition, the particles have to be brought into spatial proximity with one another.

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In Brief:

Physicists were able to simulate high-energy experimens thanks to this primitive quantum computer. Prediction of theoretical physics may soon be tested.

Our current computers are not capable of running simulations of high-energy physics experiments. However, quite recently, scientists were able to use a primitive quantum computer in the simulation of the spontaneous creation of particle-antiparticle pairs. This makes it easier for physicists to further investigate the fundamental particles. A research team published their findings in the journal, Nature.

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