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The idea was developed by graduate student Mario Krenn and colleagues in the group of quantum-physicist Anton Zeilinger. The algorithm is dubbed "Melvin", and the team believes that it might be able to explore hitherto unknown properties and behaviours of quantum systems. In doing so, Melvin would take the complexity of quantum experiments to a level beyond the imaginations of human designers.
These experiments include those with the particular goal of achieving quantum entanglement between many particles. Experimental methods for achieving entanglement of two or a very few particles are well-known. But entanglement is so counter-intuitive that it can be very difficult to see how to combine the known experimental "building blocks" to attain a more complicated state, such as "high-dimensional" entanglement between many of the particles' degrees of freedom.
Melvin works that out unencumbered by human preconceptions. The algorithm is supplied with a set of standard experimental components that it can combine and reshuffle to achieve the desired goal. These elements consist of devices for manipulating the trajectories and quantum properties of photons. These include beam splitters, which can send a photon in two possible directions, thereby putting it into a superposition of two quantum states.
An answer to a quantum-physical question provided by the algorithm Melvin has uncovered a hidden link between quantum experiments and the mathematical field of Graph Theory. Researchers from the Austrian Academy of Sciences and the University of Vienna found the deep connection between experimental quantum physics and this mathematical theory in the study of Melvin's unusual solutions, which lies beyond human intuition. They now report in the journal Physical Review Letters.
In the analysis of this solution calculated by Melvin, the researchers initially groped in the dark. Until they came up with a remarkable sequence of numbers known only in the so-called graph theory—a sophisticated area of mathematics that has been used to describe networks such as the Internet or neural networks.
The unusual approach, which would have remained hidden to quantum physicists, prompted the scientists to further investigate this connection. As they now report in the journal Physical Review Letters, there are great similarities between experimental quantum physics and mathematical graph theory: If methods and knowledge from graph theory are used to calculate and plan a quantum experiment, it is possible to make very precise and novel statements about the results. "Properties of quantum experiments can be calculated using graph theory, and questions in graph theory can be answered in quantum experiments," explains Krenn. In this way, it is also possible to grasp quantum technology as a graph or a network in order to explore new experimental possibilities.
And that sounds an awful lot like laws of physics, as James Gates, a theoretical physicist at the University of Maryland, pointed out:
"In my research I found this very strange thing. I was driven to error-correcting codes - they're what make browsers work. So why were they in the equations I was studying about quarks and electrons and supersymmetry? This brought me to the stark realisation that I could no longer say people like Max are crazy."
Source: Science Alert
After a few hours of calculation, their algorithm - which they call Melvin - found the recipe to the question they were unable to solve, and its structure surprised them. Zeilinger says: "Suppose I want build an experiment realizing a specific quantum state I am interested in. Then humans intuitively consider setups reflecting the symmetries of the state. Yet Melvin found out that the most simple realization can be asymmetric and therefore counterintuitive. A human would probably never come up with that solution."
The physicists applied the idea to several other questions and got dozens of new and surprising answers. "The solutions are difficult to understand, but we were able to extract some new experimental tricks we have not thought of before. Some of these computer-designed experiments are being built at the moment in our laboratories", says Krenn.
Melvin not only tries random arrangements of experimental components, but also learns from previous successful attempts, which significantly speeds up the discovery rate for more complex solutions.
Graph Theory has proven to be a useful tool to describe a discrete time-evolution of a given state in a system. In our investigation, we consider particles moving along the real line in a wave form, and develop a discrete version by entirely reconstructing the setup into particles moving through a graph instead. By doing so, we hope to build upon our current understanding of quantum states and how a discrete analogue of quantum evolution exists.
In the last three decades, condensed matter physicists have discovered a wonderland of exotic new phases of matter: emergent, collective states of interacting particles that are nothing like the solids, liquids and gases of common experience.
The phases, some realized in the lab and others identified as theoretical possibilities, arise when matter is chilled almost to absolute-zero temperature, hundreds of degrees below the point at which water freezes into ice. In these frigid conditions, particles can interact in ways that cause them to shed all traces of their original identities. Experiments in the 1980s revealed that in some situations electrons split en masse into fractions of particles that make braidable trails through space-time; in other cases, they collectively whip up massless versions of themselves. A lattice of spinning atoms becomes a fluid of swirling loops or branching strings; crystals that began as insulators start conducting electricity over their surfaces. One phase that shocked experts when recognized as a mathematical possibility in 2011 features strange, particle-like “fractons” that lock together in fractal patterns.
Led by dozens of top theorists, with input from mathematicians, researchers have already classified a huge swath of phases that can arise in one or two spatial dimensions by relating them to topology: the math that describes invariant properties of shapes like the sphere and the torus. They’ve also begun to explore the wilderness of phases that can arise near absolute zero in 3-D matter.
Enumerating phases of matter could have been “like stamp collecting,” Vishwanath said, “each a little different, and with no connection between the different stamps.” Instead, the classification of phases is “more like a periodic table. There are many elements, but they fall into categories and we can understand the categories.”
Qutrits, ququarts, or any other d-dimensional qudits are possible. Now Manuel Erhard and his colleagues at the Institute for Quantum Optics and Quantum Information (IQOQI) in Vienna have created a trio of entangled qutrits, the first demonstration in which more than two particles were entangled in more than two quantum states.
The researchers designed and built a femtosecond light source that produced two pairs of photons, with each pair entangled in the ℓ = 0, 1, and –1 OAM levels. The path to creating the complex entanglement between three of the photons wasn’t obvious—in fact, it required a computer’s help. Using an algorithm named Melvin that essentially plays with various configurations of quantum optics instruments, Erhard and coworkers developed a novel device that consisted of a beamsplitter, nested interferometers, and more. As shown in the diagram, the multiport processed three photons at a time—previous multiphoton-entanglement experiments manipulated only two—and transformed some of the correlations between OAM levels. Simultaneous clicks in four final photon detectors signaled that two of the photons exiting the multiport, B and C, plus photon D, were entangled in three dimensions.
The new technique opens the possibility of conducting more complex tests to rule out local realism alternatives to quantum mechanics. Researchers could also exploit high-dimensional-encoded photons to design quantum systems that carry more information and are less susceptible to eavesdropping. (M. Erhard et al., Nat. Photonics, 2018,
An alternative route is to increase the number of entangled quantum levels. Here, we overcome present experimental and technological challenges to create a three-particle GHZ state entangled in three levels for every particle. The resulting qutrit-entangled states are able to carry more information than entangled states of qubits. Our method, inspired by the computer algorithm Melvin, relies on a new multi-port that coherently manipulates several photons simultaneously in higher dimensions.
If matter and antimatter were represented by odds and even numbers. To describe an odd number as having symmetry. How? You can always find your position with odd numbers by choosing the central number. Each side of you to the left and right are now symmetrical. Now. If you remove the middle number. which was an odd number. You have an even number to your left in descending order. And. an even number to the right in ascending order. Those 2 even numbers are antimatter. The next 2 numbers to the side of them are odd numbers. Matter one descending and one ascending. And, so on. Maybe other matter is represented by ascending and descending numbers. With even numbers. You have no true position except by a half integer. If you position yourself in front of an even number. There is no symmetry. Your always left with more numbers to either the left or right.
Time is on the curve of the wave. Number a curve with an odd number. Start at the central number. Work with odd numbers. Remove an amount of odd numbers from centre. You will be left with a gap. And, the two numbers each side of gap will be matter particles. The size of particle is determined by how many amount points it has. On the numbered curve. You can see all the matter particle pairs and the antimatter pairs. Because it's on a curve. It has time included in it too.