Princeton Scientist Makes a Leap in Quantum Computing
Princeton University's Jason Petta.
A major hurdle in the ambitious quest to design and construct a radically new kind of quantum computer has been finding a way to manipulate the single electrons that very likely will constitute the new machines’ processing components or “qubits.”
has discovered how to do just that — demonstrating a method that alters the properties of a lone electron without disturbing the trillions of electrons in its immediate surroundings. The feat is essential to the development of future varieties of superfast computers with near-limitless capacities for data.
Petta, an assistant professor of physics, has fashioned a new method of trapping one or two electrons in microscopic corrals created by applying voltages to minuscule electrodes. Writing in the Feb. 5 edition of Science, he describes how electrons trapped in these corrals form “spin qubits,” quantum versions of classic computer information units known as bits. Other authors on the paper include Art Gossard and Hong Lu at the University of California-Santa Barbara.
Previous experiments used a technique in which electrons in a sample were exposed to microwave radiation. However, because it affected all the electrons uniformly, the technique could not be used to manipulate single electrons in spin qubits. It also was slow. Petta’s method not only achieves control of single electrons, but it does so extremely rapidly — in one-billionth of a second. (more…)
Quantum Computer Chips Now One Step Closer to Reality
by Pam Frost Gorder
Paul Berger
In the quest for smaller, faster computer chips, researchers are increasingly turning to quantum mechanics — the exotic physics of the small.
The problem: the manufacturing techniques required to make quantum devices have been equally exotic.
That is, until now.
Researchers at Ohio State University have discovered a way to make quantum devices using technology common to the chip-making industry today.
This work might one day enable faster, low-power computer chips. It could also lead to high-resolution cameras for security and public safety, and cameras that provide clear vision through bad weather.
Paul Berger, professor of electrical and computer engineering and professor of physics at Ohio State University, and his colleagues report their findings in an upcoming issue of IEEE Electron Device Letters.
The team fabricated a device called a tunneling diode using the most common chip-making technique, called chemical vapor deposition. (more…)
Sustained Quantum Processing in Step Toward Building Quantum Computers
NIST physicists demonstrated sustained, reliable quantum information processing in the ion trap at the left center of this photograph, improving prospects for building a practical quantum computer. The ions are trapped inside the dark slit(3.5 millimeters long and 200 micrometers wide)between the gold-covered alumina wafers. By changing the voltages applied to each of the gold electrodes, scientists can move the ions between the six zones of the trap. (Credit: J. Jost/NIST)
Raising prospects for building a practical quantum computer, physicists at the National Institute of Standards and Technology (NIST) have demonstrated sustained, reliable information processing operations on electrically charged atoms (ions). The new work, described in the August 6 issue of Science Express,* overcomes significant hurdles in scaling up ion-trapping technology from small demonstrations to larger quantum processors.
In the new demonstration, NIST researchers repeatedly performed a combined sequence of five quantum logic operations and ten transport operations while reliably maintaining the 0s and 1s of the binary data stored in the ions, which serve as quantum bits (qubits) for a hypothetical quantum computer, and retaining the ability to subsequently manipulate this information. Previously, scientists at NIST and elsewhere have been unable to coax any qubit technology into performing a complete set of quantum logic operations while transporting information, without disturbances degrading the later processes. (more…)
Securing Data Against Future Quantum Hacking and Cracking
The first desktop computers changed the way we managed data forever. Three decades after their introduction, we rely on them to manage our time, social life and finances — and to keep this information safe from prying eyes and online predators.
So far, so good, despite an occasional breach. But our security and our data could be compromised overnight when the first quantum computer is built, says Dr. Julia Kempe of Tel Aviv University’s Blavatnik School of Computer Science. These new computers, still in the theoretical stage, will be many times more powerful than the computers that protect our data now. (more…)
Physicists Find Way to Control Individual Bits in Quantum Computers
Optical lattices use lasers to separate rubidium atoms (red) for use as information "bits" in neutral-atom quantum processors -- prototype devices which designers are trying to develop into full-fledged quantum computers. NIST scientists have managed to isolate and control pairs of the rubidium atoms with polarized light, an advance that may bring quantum computing a step closer to reality. (NIST))
Physicists at the National Institute of Standards and Technology (NIST) have overcome a hurdle in quantum computer development, having devised* a viable way to manipulate a single “bit” in a quantum processor without disturbing the information stored in its neighbors. The approach, which makes novel use of polarized light to create “effective” magnetic fields, could bring the long-sought computers a step closer to reality.
A great challenge in creating a working quantum computer is maintaining control over the carriers of information, the “switches” in a quantum processor while isolating them from the environment. These quantum bits, or “qubits,” have the uncanny ability to exist in both “on” and “off” positions simultaneously, giving quantum computers the power to solve problems conventional computers find intractable – such as breaking complex cryptographic codes. (more…)
Scientists Create First Electronic Quantum Processor
The two-qubit processor is the first solid-state quantum processor that resembles a conventional computer chip and is able to run simple algorithms. (Blake Johnson/Yale University)
A team led by Yale University researchers has created the first rudimentary solid-state quantum processor, taking another step toward the ultimate dream of building a quantum computer.
They also used the two-qubit superconducting chip to successfully run elementary algorithms, such as a simple search, demonstrating quantum information processing with a solid-state device for the first time. Their findings will appear in Nature’s advanced online publication June 28.
“Our processor can perform only a few very simple quantum tasks, which have been demonstrated before with single nuclei, atoms and photons,” said Robert Schoelkopf, the William A. Norton Professor of Applied Physics & Physics at Yale. “But this is the first time they’ve been possible in an all-electronic device that looks and feels much more like a regular microprocessor.” (more…)
Researchers Develop Powerful Method of Suppressing Errors in Quantum Computers
Under certain conditions, trapped beryllium ions form a hexagonal single-plane crystal. This crystal consists of about 300 ions that are spaced about 10 micrometers apart and are fluorescing (scattering laser light). An array of ions such as this might be used as a memory device in a quantum computer. (Credit: NIST)
Researchers at the National Institute of Standards and Technology (NIST) have demonstrated a technique for efficiently suppressing errors in quantum computers. The advance could eventually make it much easier to build useful versions of these potentially powerful but highly fragile machines, which theoretically could solve important problems that are intractable using today’s computers.
The new error-suppression method, described in the April 23 issue of Nature,* was demonstrated using an array of about 1,000 ultracold beryllium ions (electrically charged atoms) trapped by electric and magnetic fields. Each ion can act as a quantum bit (qubit) for storing information in a quantum computer. These ions form neatly ordered crystals, similar to arrays of qubits being fabricated by other researchers using semiconducting and superconducting circuitry. Arrays like this potentially could be used as multi-bit quantum memories. (more…)
Building a Quantum Computer
The NRC-IMS team of Drs. Pawel Hawrylak, Andy Sachrajda, Sergei Studenikin and Guy Austing (left to right), with a liquid helium cryostat. The cryostat cools equipment that measures NRC's semiconductor quantum dot structures.
Today’s computers, from laptops to supercomputers, employ microchips that contain millions of tiny transistors. Each transistor is a kind of on-off switch that directs streams of millions of electrons representing binary zeros and ones that form the basis for all digital computing.
But what if a computer exclusively used the quantum properties of electrons rather than their classical properties? These computers would transcend today’s microprocessors by following completely different quantum physics rules to solve problems.
The NRC-IMS team of Drs. Pawel Hawrylak, Andy Sachrajda, Sergei Studenikin and Guy Austing (left to right), with a liquid helium cryostat. The cryostat cools equipment that measures NRC’s semiconductor quantum dot structures.
“There’s a whole class of mathematical problems that are very, very hard to do with a regular computer, even if it’s very fast. But if you can build a quantum computer, some of these problems become much easier to do,” says Dr. Guy Austing of the NRC Institute for Microstructural Sciences (NRC-IMS) in Ottawa.
Dr. Austing is quick to point out that useful quantum computers, first envisaged about 50 years ago, could take up to another 50 years to build. But Canada National Research Council teams are working on it. And many other university, military and commercial electronics research groups around the world are doing basic research in many directions to find the best ways to employ atoms, ions, photons, superconductors and semiconductors for quantum calculations.
The approach of Dr. Austing and his colleagues involves nano-electronics based on gallium arsenide semiconductor structures called “quantum dots” that can work even with one or two electrons at a time. Gallium arsenide is already used in some specialized electronics, so it’s possible that quantum computers could be built using current manufacturing equipment and processes. However, “the behaviour we see in the transistors we are now investigating is quite different than what you see in today’s commercial transistors,” stresses Dr. Austing.
He explains that while today’s computer transistors control the flow of basic “bits” of binary information, quantum computers would shuffle different, more complicated information units called “qubits.” One of the main quantum properties of a qubit, called “superposition,” means that rather than being in a state of either zero or one, it can be in an intermediate state — a combination of zero and one at the same time. Another property, called “entanglement,” means that if a certain quantum object was split in two, for instance, a measurement on one part at one location would influence the outcome of the measurement on the other part at another location, no matter how far apart the two locations.
While these concepts may boggle non-physicists, in simple terms they mean that a quantum computer may excel at performing a number of well-known mathematical algorithms related to certain important, “exponentially difficult” problems.
If a quantum computer can be built, says Dr. Austing, “it would not be a universal panacea.” We’re unlikely to use them in our laptops or mobile phones. The silicon-based microchips already in common use are best for those.
However, quantum computers could model the workings of quantum systems — like atoms and molecules — giving us a far better understanding of the building blocks of matter. Simulating new biological, chemical or pharmaceutical molecules faster and better would affect many lives — the total combined economic value of these industries was recently estimated at about $3 trillion annually around the world, says Dr. Austing.
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