Photo via flickr by colbalt123
Physicists at UC Santa Barbara have made an important advance in electrically controlling quantum states of electrons, a step that could help in the development of quantum computing.
The researchers have demonstrated the ability to electrically manipulate, at gigahertz rates, the quantum states of electrons trapped on individual defects in diamond crystals. This could aid in the development of quantum computers that could use electron spins to perform computations at unprecedented speed.
Using electromagnetic waveguides on diamond-based chips, the researchers were able to generate magnetic fields large enough to change the quantum state of an atomic-scale defect in less than one billionth of a second. The microwave techniques used in the experiment are analogous to those that underlie magnetic resonance imaging (MRI) technology.
The key achievement in the current work is that it gives a new perspective on how such resonant manipulation can be performed. “We set out to see if there is a practical limit to how fast we can manipulate these quantum states in diamond,” said lead author Greg Fuchs, a postdoctoral researcher at UCSB. “Eventually, we reached the point where the standard assumptions of magnetic resonance no longer hold, but to our surprise we found that we actually gained an increase in operation speed by breaking the conventional assumptions.”
While these results are unlikely to change MRI technology, they do offer hope for the nascent field of quantum computing. In this field, individual quantum states take on the role that transistors perform in classical computing.
“From an information technology standpoint, there is still a lot to learn about controlling quantum systems,” said David Awschalom, principal investigator and professor of physics, electrical and computer engineering at UCSB. “Still, it’s exciting to stand back and realize that we can already electrically control the quantum state of just a few atoms at gigahertz rates — speeds comparable to what you might find in your computer at home.”
The work was performed at UCSB’s Center for Spintronics and Quantum Computation, directed by Awschalom.
Via ScienceDaily and University of California – Santa Barbara
In a conversation with Sputnik Observatory, Bernard Haisch, astrophysicist, chronicles the quest to crack the laws of the quantum world; to reveal its mysteries and energies at the microscopic level.
Now what road would we have gone down, if in 1913 Niels Bohr had not just formulated the first of his quantum laws, or what I suppose you would call a quantum fiat, a dictum, a rule that he pulled out of the air, very successfully pulled entirely out of the air. And the question is, what would have happened to physics had he not done that? Would we have developed the idea of a sea of energy, zero point energy filling the universe, and investigating the consequences of that, and perhaps discovering that some of the quantum mysteries of the time could have been resolved using that approach, rather than the development of a whole new physics? That, of course, is a question no one can answer because that’s the road we didn’t go down. And who knows what kind of discoveries we would have made on a road we didn’t go down 75 years ago? But within the last thirty years that road has been taken up again by a few explorers. And one of the earliest explorers was a physicist, a British physicist named Trevor Marshall, who in 1963, I would say perhaps did not single-handedly resurrect, but certainly was one of the key figures in resurrecting this old way of thinking of space as being filled with a sea of zero point energy, and applying the ordinary laws of classical Newtonian physics to whatever circumstances we want it to represent to model, but adding to classical physics the idea of an underlying sea of zero point energy. He developed this approach and it was taken up a few years later by a very clever scientist, at the City University of New York, named Timothy Boyer, who took it much further. And together, over the next ten years, I don’t think they worked together, but together in public, publication of papers side by side, this approach was taken. This was, to some extent, the road that had been abandoned fifty years ago. And their objective was to try to develop the understanding of quantum laws using this semi-classical representation. And so you ask yourself, we have all sorts of quantum mysteries that have been explored and discovered since the 1920s, that presumably required the existence of a set of laws that are purely quantum, they’re not intuitive. It’s been said that if you think you understand quantum mechanics, that’s proof by definition that you don’t, because the laws are not intuitive, they don’t seem to make sense, they seem to contradict our everyday experience, and yet it’s been a highly successful way to develop our understanding of the microscopic world.