Scientists demonstrate one of largest quantum simulators - Politics Forum.org | PoFo

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Physicists at MIT and Harvard University have demonstrated a new way to manipulate quantum bits of matter. In a paper published today in the journal Nature, they report using a system of finely tuned lasers to first trap and then tweak the interactions of 51 individual atoms, or quantum bits.

The team's results represent one of the largest arrays of quantum bits, known as qubits, that scientists have been able to individually control. In the same issue of Nature, a team from the University of Maryland reports a similarly sized system using trapped ions as quantum bits.

In the MIT-Harvard approach, the researchers generated a chain of 51 atoms and programmed them to undergo a quantum phase transition, in which every other atom in the chain was excited. The pattern resembles a state of magnetism known as an antiferromagnet, in which the spin of every other atom or molecule is aligned.

The team describes the 51-atom array as not quite a generic quantum computer, which theoretically should be able to solve any computation problem posed to it, but a "quantum simulator"—a system of quantum bits that can be designed to simulate a specific problem or solve for a particular equation, much faster than the fastest classical computer.

For instance,the team can reconfigure the pattern of atoms to simulate and study new states of matter and quantum phenomena such as entanglement. The new quantum simulator could also be the basis for solving optimization problems such as the traveling salesman problem, in which a theoretical salesman must figure out the shortest path to take in order to visit a given list of cities. Slight variations of this problem appear in many other areas of research, such as DNA sequencing, moving an automated soldering tip to many soldering points, or routing packets of data through processing nodes.

"This problem is exponentially hard for a classical computer, meaning it could solve this for a certain number of cities, but if I wanted to add more cities, it would get much harder, very quickly," says study co-author Vladan Vuleti?, the Lester Wolfe Professor of Physics at MIT. "For this kind of problem, you don't need a quantum computer. A simulator is good enough to simulate the correct system.So we think these optimization algorithms are the most straightforward tasks to achieve."

The work was performed in collaboration with Harvard professors Mikhail Lukin and Markus Greiner; MIT visiting scientist Sylvain Schwartz is also a co-author.

Separate but interacting

Quantum computers are largely theoretical devices that could potentially carry out immensely complicated computations in a fraction of the time that it would take for the world's most powerful classical computer. They would do so through qubits—data processing units which, unlike the binary bits of classical computers, can be simultaneously in a position of 0 and 1. This quantum property of superposition allows a single qubit to carry out two separate streams of computation simultaneously.Adding additional qubits to a system can exponentially speed up a computer's calculations.

But major roadblocks have prevented scientists from realizing a fully operational quantum computer. One such challenge: how to get qubits to interact with each other while not engaging with their surrounding environment.

"We know things turn classical very easily when they interact with the environment, so you need [qubits] to be super isolated," says Vuleti?, who is a member of the Research Laboratory of Electronics and the MIT-Harvard Center for Ultracold Atoms. "On the other hand, they need to strongly interact with another qubit."

Some groups are building quantum systems with ions, or charged atoms, as qubits. They trap or isolate the ions from the rest of the environment using electric fields; once trapped, the ions strongly interact with each other. But many of these interactions are strongly repelling, like magnets of similar orientation, and are therefore difficult to control, particularly in systems with many ions.

Other researchers are experimenting with superconducting qubits—artificial atoms fabricated to behave in a quantum fashion. But Vuleti? says such manufactured qubits have their disadvantages compared with those based on actual atoms.

"By definition, every atom is the same as every other atom of the same species," Vuleti? says."But when you build them by hand, then you have fabrication influences, such as slightly different transition frequencies, couplings, et cetera."

Setting the trap

Vuleti? and his colleagues came up with a third approach to building a quantum system, using neutral atoms—atoms that hold no electrical charge—as qubits. Unlike ions, neutral atoms do not repel each other, and they have inherently identical properties, unlike fabricated superconducting qubits.

In previous work, the group devised a way to trap individual atoms, by using a laser beam to first cool a cloud of rubidium atoms to close to absolute zero temperatures, slowing their motion to a near standstill. They then employ a second laser, split into more than 100 beams, to trap and hold individual atoms in place. They are able to image the cloud to see which laser beams have trapped an atom, and can switch off certain beams to discard those traps without an atom. They then rearrange all the traps with atoms, to create an ordered, defect-free array of qubits.

With this technique, the researchers have been able to build a quantum chain of 51 atoms, all trapped at their ground state, or lowest energy level.

In their new paper, the team reports going a step further, to control the interactions of these 51 trapped atoms, a necessary step toward manipulating individual qubits.To do so, they temporarily turned off the laser frequencies that originally trapped the atoms, allowing the quantum system to naturally evolve.

They then exposed the evolving quantum system to a third laser beam to try and excite the atoms into what is known as a Rydberg state—a state in which one of an atom's electrons is excited to a very high energy compared with the rest of the atom's electrons. Finally, they turned the atom-trapping laser beams back on to detect the final states of the individual atoms.

"If all the atoms start in the ground state, it turns out when we try to put all the atoms in this excited state, the state that emerges is one where every second atom is excited," Vuleti? says. "So the atoms make a quantum phase transition to something similar to an antiferromagnet."

The transition takes place only in every other atom due to the fact that atoms in Rydberg states interact very strongly with each other, and it would take much more energy to excite two neighboring atoms to Rydberg states than the laser can provide.

Vuleti? says the researchers can change the interactions between atoms by changing the arrangement of trapped atoms, as well as the frequency or color of the atom-exciting laser beam. What's more, the system may be easily expanded.
"We think we can scale it up to a few hundred," Vuleti? says. "If you want to use this system as a quantum computer, it becomes interesting on the order of 100 atoms, depending on what system you're trying to simulate."

For now, the researchers are planning to test the 51-atom system as a quantum simulator, specifically on path-planning optimization problems that can be solved using adiabatic quantum computing—a form of quantum computing first proposed by Edward Farhi, the Cecil and Ida Green Professor of Physics at MIT.

Adiabatic quantum computing proposes that the ground state of a quantum system describes the solution to the problem of interest.When that system can be evolved to produce the problem itself, the end state of the system can confirm the solution.

"You can start by preparing the system in a simple and known state of lowest energy, for instance all atoms in their ground states, then slowly deform it to represent the problem you want to solve, for instance, the traveling salesman problem," Vuleti? says. "It's a slow change of some parameters in the system, which is exactly what we do in this experiment. So our system is geared toward these adiabatic quantum computing problems."

https://phys.org/news/2017-11-quantum-s ... rties.html


RT said:
Quantum consciousness (remember our tools/tech re-shape our perception due to the nature of the information feed-back loop all 'things' co-inhabit/create together), you know- the 1 and 0 simultaneously (a field of vibratory frequencies weaving reality), will replace dialectical logic (dialectical knowledge will continue to exist as a form of 3D awareness, underneath multi-dimensional logic systems. Think about what occurs when any new technology obsolesces old technology...) binary thought structures or manifestations of binary thought will be malleable and programmable parts, and linear-sequential-orderly thought will be a thing of the past because systems thinking or holistic logic will be able to enter an information 'happening' from any point in the data-sphere and all information shall be available through fully integrated computer knowledge stored in hyperspace. The 3D world will become a malleable playground, due to the bond formed with our artificial hyperspace, humans will be able to simulate a technological form of kaleidoscopic awareness and analyze the potential energy unfolding in the physical/3D world.
By RhetoricThug
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4D World: Light Moving In Fourth Dimension Observed During Quantum Hall Experiment

Any mention of the fourth dimension and our mind immediately wanders to the possible wonders of time travel. Since Albert Einstein’s Theory of Relativity was introduced in 1905, the fourth dimension is said to be time any movement along this dimension would cause the object to move forward or backward in time.

In our physical world, we can perceive three dimensions and one extra dimension of time as we move through the Universe. But, two quantum experiments have shown the existence of a fourth spatial dimension for the first time.

The teams of scientists from U.S. and Europe have shown that, in addition to the conventional three-axis where an object can move up-down, left-right or forward and backward to an observer, there exists a fourth spatial dimension could introduce new directions of motion.

The discovery was made by studying the results of two quantum hall experiments. The quantum Hall effect happens when the motion of an electron in a material is restricted to only 2D. When an electron system is subjected to very high magnetic fields perpendicular to the material at very low temperatures initially leads to what is observed as the quantum Hall effect where the voltage no longer increases continuously like seen in the conventional Hall effect, but rather jumps in discrete steps.

During this effect, it is observed that electrons can only move in well-defined topological pathways that are pre-determined. For particular strengths of the magnetic field, the electric current can only flow along the edges of the material. This effect, which was observed 20 years ago, was said to be similar to what would happen to particles in the fourth-dimension.

Oded Zilberberg, ETH researcher, and a professor at the Institute for Theoretical Physics overlooked the two experiments that provided the data for the discovery. By placing together two specially designed 2D setups to study the quantum Hall effect, they were able to catch a glimpse of this fourth spatial dimension.

The team used specially designed topological pumps that helped modulate a specific parameter of the physical system in which the quantum Hall effect was observed. This causes quantum states to change in a pre-determined way. This change, the team noted, was analogous to how they expected the system to react when it was moving in an additional spatial dimension.

The 2D system immediately became a 4D system.

This was not just a flash in the pan either. A team of physicists from Penn State University and the University of Pittsburgh applied the idea birthed by Zilberberg by burning a two-dimensional array of waveguides into a fifteen-centimeter-long glass block using laser beams.

These waveguides were cut into the glass in random pathways, such that the distances between them varied along the glass block at different points. As the distances between the waveforms changed, the light waves (lasers) moving through the waveguides could jump easily to a neighboring waveguide.

As the team experimented with different waveguides, they found that they acted as topological pumps. The light was passed through the glass block and through the various waveforms. They recorded the light that emerged after passing through the glass. They found the edge state particles of the previously theoretically proven fourth dimension in the quantum Hall effect. Light from the edge of the lattice, became directly visible, which showed the researchers the particles moving through the fourth dimension.

So what’s the practical use of all this? “Right now, those experiments are still far from any useful application,” Zilberberg admits. But, scientists now have an idea of what to study when it comes to exploring the fourth dimension. We can study quasicrystals in metallic alloys which have no discernible pattern in when viewed in 3D space but when one looks at them in higher virtual dimensions, they actually exhibit regular patterns.

The team feels that this could aid the world’s study of string theory, according to which higher dimensions are just compressed in such a way that only our normal three-dimensional world exists.

A four-dimensional space or 4D space has been derived mathematically years ago. The concept is just an extension of the existing three-dimensional or 3D space all humans see.This 3D space we share is seen as the simplest possible generalization of the space around us.

The three axis are used to describe the sizes or locations of objects we see in the everyday world and also helps us place them spatially. For example, the volume of a rectangular box is found by measuring its length (often labeled x), width (y), and depth (z) which are the three dimensions of the object whereas a 2D rectangle uses only the its length and breadth. The geometry of four-dimensional space is much more complex than that of three-dimensional space, due to the extra degree of freedom.
http://www.ibtimes.com/4d-world-light-m ... nt-2638484

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