System Bits: Aug. 16

Record-breaking quantum logic gate
Reaching the benchmark required theoretically to build a quantum computer, University of Oxford researchers have achieved a quantum logic gate with record-breaking 99.9% precision.

They reminded that quantum computers, which function according to the laws of quantum physics, have the potential to dwarf the processing power of today’s computers, able to process huge amounts of information all at once. They said they achieved the logic gate — which places two atoms in a state of quantum entanglement, and is the fundamental building block of quantum computing — with a precision substantially greater than the previous world record. Quantum entanglement is a phenomenon described by Einstein as ‘spooky,’ and is at the heart of quantum technologies; it occurs when two particles stay connected, such that an action on one affects the other, even when they are separated by great distances.

The research was conducted by scientists from the Engineering and Physical Sciences Research Council (EPSRC)-funded Networked Quantum Information Technologies Hub (NQIT), led by Oxford University.

The Oxford team used the ion trap device seen on the right of the image to achieve their record.
(Source: Oxford University)

The researchers explained that the concept of quantum entanglement is fundamental to quantum computing and describes a situation where two quantum objects – in this case, two individual atoms – share a joint quantum state. That means that measuring a property of one of the atoms tells you something about the other. A quantum logic gate is an operation which can take two independent atoms and put them into this special entangled state.

Finally, they summarized that they have finally worked out how to build a transistor with good enough performance to make logic circuits, but the technology for wiring thousands of those transistors together to build an electronic computer is still in its infancy.

New language speeds computer simulations 200-fold
A team of researchers from MIT’s Computer Science and Artificial Intelligence Laboratory, Adobe, the University of California at Berkeley, the University of Toronto, Texas A&M, and the University of Texas have developed a new programming language called Simit that handles the required switching automatically between levels of description in computer simulations.

They reminded that computer simulations of physical systems are common in science, engineering, and entertainment, but they use several different types of tools, that leverage very precise physical models or simpler, higher-level descriptions.

Switching back and forth between the two levels of description is difficult not only for computer programmers but for computers as well. The team said that in experiments, simulations written in Simit were dozens or even hundreds of times as fast as those written in existing simulation languages, and required only one-tenth as much code as meticulously hand-optimized simulations that could achieve similar execution speeds.

Simulations written in Simit, a new programming language, were dozens or even hundreds of times as fast as those written in existing simulation languages. But they required only one-tenth as much code as meticulously hand-optimized simulations that could achieve similar execution speeds.
(Source: MIT)

Interestingly, Fredrik Kjolstad, an MIT graduate student in electrical engineering and computer science and first author on a new paper describing Simit said, “The story of this paper is that the trade-off between concise code and good performance is false. It’s not necessary, at least for the problems that this applies to. But it applies to a large class of problems.”

In fact, the researchers said Simit has applications outside physical simulation, in machine learning, data analytics, optimization, and robotics, among other areas.

Kjolstad said he and his colleagues have already used Simit to implement a version of Google’s original PageRank algorithm for ordering search results, and they’re currently collaborating with researchers in MIT’s Department of Physics on an application in quantum chromodynamics, a theory of the “strong force” that holds atomic nuclei together.

Sending mechanical signals through soft materials
In order to build autonomous soft systems, like soft robots, there must be a way to transmit energy through soft materials. Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), in collaboration with colleagues at the California Institute of Technology, have developed a way to send mechanical signals through soft materials.

Jordan Raney, postdoctoral fellow at SEAS and first author of the paper on the topic said soft autonomous systems have received a lot of attention because, just like the human body or other biological systems, they can be adaptive and perform delicate movements, but the highly dissipative nature of soft materials limits or altogether prevents certain functions. By storing energy in the architecture itself the team said they can make up for the energy losses due to dissipation, allowing the propagation of mechanical signals across long distances.

The system uses the centuries-old concept of bistable beams — structures stable in two distinct state — to store and release elastic energy along the path of a wave. This system consists of a chain of bistable elastomeric beams connected by elastomeric linear springs. When those beams are deformed, they snap and store energy in the form of elastic deformation. As the signal moves down the elastomer, it snaps the beams back into place, releasing the stored energy and sending the signal downstream like a line of dominos. The bistable system prevents the signal from dissipating downstream, they explained.

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