While a variety of quantum systems exist today, many are unable to scale to solve some of the world’s most challenging problems. Explaining the real-world obstacles of building a quantum system that scales, this post explores how Microsoft addresses these challenges through a topological qubit.
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.
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!
Posted in computing, particle physics, quantum physics | Leave a Comment on Toward tailoring Majorana bound states in artificially constructed magnetic atom chains on elemental superconductors
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).
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.
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:
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.
An argument against Evangelism
This isn’t a rant against personal faith. It is a rant against the idea that you should ‘push’ your views on unrelated individuals, especially strangers—even if you believe that your view offers salvation.
Anyone who has lived in a home or apartment, dormed at a college or housed in the military has been approached by well-intentioned Mormons, Jehovah’s Witness, Baptists, Hari Krishna or other evangelicals. I hold nothing against such missionaries. They are marketing conscience and faith in what they see as an act of love. Unfortunately, society is worse off for this type of love. They are horribly misguided. They mean well and they may have the inside track on creation, but their understanding of equality and civil liberties is naïve.
Is this a position of Intolerance? — Quite the opposite!
Even in far off lands, instant communication, air travel and nuclear weapons render our fiefdoms meaningless beyond the realms of taxation, defense, and road repair. We live in a pluralistic melting pot. The shrinking planet demands that we coexist. I have always felt that the only thing of which we can be intolerant is intolerance itself.
So, why do I shun religious outreach? Because, arguing that your book is better than mine can only be won on faith—and faith is both personal and unprovable. Sure, tolerance is often built on religious ideals. To function as a society without killing each other, tolerance is a necessity. But, tolerance and humanity are also built into the Golden Rule and every democratic constitution. Any attempt to persuade others to adopt your core beliefs about origin, doctrine or blasphemy is pointless and an affront to everyone elses’ beliefs.
Whew! It took courage to get that off my chest. I hope that my friend, Hiawatha Bray forgives me.
What about the contradiction between science and religion?
I have never seen any contradiction. Only someone who believes that the Earth was created in the past 6,000 years ago sees a contradiction. That belief is as goofy as the sun orbitting the earth.
If there is a God, then I suppose it explains the energy and matter that surrounds us. And if this is the case, he followed up by proclaiming the finely tuned natural laws of physics and biochemistry, and set everything in motion. Oh rejoice in his splendor! Because, after billions of years, life arose—and we are the interim products of an expanding universe. It’s awe-inspiring, but it certainly presents no contradiction.
I don’t consider myself an atheist. And despite offering an agnostic explanation of the universe, my religion is my business and not yours. But, I certainly believe in science! I side with Bill Nye and the late Carl Sagan (he was my former professor). No one with a sense of their surroundings and an appreciation for facts can ignore that the Earth and the universe have existed for billions of years.
We may be the product of an intelligent God, but if we are, we will never know. We lack to tools to discern the question that predates all other questions. Pointing to ancient scripture is nonsense. The scripture was written by men, seeking to explain everything that they observed in their times. Yet, these men had fewer facts about the universe than we have now. The faith that most believers associate with scripture is based on respect for the practices and beliefs of their parents.
Moreover, the men who created these book (the bibles of any religion), also created God. Why? To deal with mortality, explain tragedy, control the masses—or perhaps as a mental exercise. It may even be a byproduct of what they were ingesting and smoking.
