New research gives insight into a recent experiment that was able to manipulate an unprecedented number of atoms through a quantum simulator. This new theory could provide another step on the path to creating the elusive quantum computers.
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Category: quantum physics – Page 815
Quantum theory is based heavily on probabilities, since measuring a quantum system doesn’t produce the same outcome every time, but instead yields one of many outcomes that each occur with a certain probability. Now in a new paper, physicists have presented a new quantum probability rule for assigning probabilities to measurement outcomes, or events, that essentially combines two of the most important quantum probability rules (the Born rule and the wave function collapse rule) into one.
The physicists, Sally Shrapnel, Fabio Costa, and Gerard Milburn, at The University of Queensland in Australia, have published a paper on the new quantum probability rule in the New Journal of Physics.
One of the most important probability rules in quantum theory is the Born rule, which gives the probability that a measurement yields a certain event. However, things get a little bit more complicated when predicting consecutive events. Although in classical scenarios it’s possible to assign joint probabilities to consecutive events using conditioning, in quantum scenarios this is not possible since each measurement necessarily disturbs the system. So in quantum mechanics, the state must be updated with this new information after every measurement.
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Superconductors are among the most bizarre and exciting materials yet discovered. Counterintuitive quantum-mechanical effects mean that, below a critical temperature, they have zero electrical resistance. This property alone is more than enough to spark the imagination.
A current that could flow forever without losing any energy means transmission of power with virtually no losses in the cables. When renewable energy sources start to dominate the grid and high-voltage transmission across continents becomes important to overcome intermittency, lossless cables will result in substantial savings.
What’s more, a superconducting wire carrying a current that never, ever diminishes would act as a perfect store of electrical energy. Unlike batteries, which degrade over time, if the resistance is truly zero, you could return to the superconductor in a billion years and find that same old current flowing through it. Energy could be captured and stored indefinitely!
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Realizing Majorana bound states (MBS) in condensed matter systems is a key challenge on the way toward topological quantum computing. As a promising platform, one-dimensional magnetic chains on conventional superconductors were theoretically predicted to host MBS at the chain ends. We demonstrate a novel approach to design of model-type atomic-scale systems for studying MBS using single-atom manipulation techniques. Our artificially constructed atomic Fe chains on a Re surface exhibit spin spiral states and a remarkable enhancement of the local density of states at zero energy being strongly localized at the chain ends. Moreover, the zero-energy modes at the chain ends are shown to emerge and become stabilized with increasing chain length. Tight-binding model calculations based on parameters obtained from ab initio calculations corroborate that the system resides in the topological phase. Our work opens new pathways to design MBS in atomic-scale hybrid structures as a basis for fault-tolerant topological quantum computing.
Majorana fermions —particles being their own antiparticles—have recently attracted renewed interest in various fields of physics. In condensed matter systems, Majorana bound states (MBS) with a non-Abelian quantum exchange statistics have been proposed as a key element for topological quantum computing (2–4). One of the most promising platforms to realize MBS are one-dimensional (1D) helical spin systems being proximity-coupled to a conventional s-wave superconductor (5–9). In such a surface-confined system, the MBS can directly be investigated by local probe techniques such as scanning tunneling microscopy/spectroscopy (STM/STS). Previously reported experiments aiming at the direct visualization and probing of the MBS have focused on self-assembled magnetic chains on superconducting Pb substrates (10–15).
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A technique to manipulate electrons with light could bring quantum computing up to room temperature.
A team of researchers in Germany and at the University of Michigan have demonstrated how infrared laser pulses can shift electrons between two different states, the classic 1 and 0, in a thin sheet of semiconductor.
“Ordinary electronics are in the range of gigahertz, one billion operations per second. This method is a million times faster,” said Mackillo Kira, U-M professor of electrical engineering and computer science.
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Ironically, my more popular posts are ones furthest from my passion and core interests. They are larks—never intended to go viral. This is about one of them…
Apart from family, I typically steer clear of religious topics. I identify with a mainstream religion, but it is completely beside the purpose of Lifeboat Foundation, and it is a personal affair.[1]
Yet, here we discuss a religious topic, after all. Let’s get started…
Question
Do atheists agree that the fact that we can’t understand
quantum physics is at least somewhat evidence of Allah?
An Objective Answer
Do you assert that a failure to understand something is evidence of God?
I don’t fully understand a triple-Lutz (ice skating) or the Jessica stitch (needlepoint)—and I certainly don’t get why an electric dryer leaves moisture on light weight linens, when a gas dryer gets them bone-dry before the plush towels.
Is my inability to solve these mysteries evidence of Allah (or Yahweh, haShem or Y’Shewa)? Of course, not! It has nothing to do with God or religion. The fact that I don’t quite grasp every complex task or unexplained science is not evidence of God, it is evidence of my own ignorance.
On the other hand, I am fortunate to understand quantum physics—both academically and from an innate perspective. That is, behavior of waves and matter on a subatomic scale make perfect sense to me.
You would be correct to point out that certain quantum behavior seems to violate common sense:
- Probabilistic behavior. (i.e. Schrödinger’s cat is both dead and alive at once)
- Measure photons or electrons as a wave, and it no longer behaves like particles
- Entangled electrons (Einstein called it ‘Spooky action at a distance’)
- The EPR Paradox (entanglement experiment demonstrates causality based on future knowledge. It seems profoundly unbelievable!)
But these things only seem strange, because we do not experience them first hand given our size and our senses. As the math and the mechanisms are understood through research and experimentation, the behavior begins to fit within physical laws as we understand them. Then, we can extrapolate (predict) other behaviors.
For example, as we begin to understand quantum mechanics, we can design a computer, an encryption mechanism—and eventually a teleportation system—that exploits the physical properties and laws.
1 I do not appreciate the outreach of evangelism. In my opinion, religious discussion is best amongst a like-minded community.
