The world of quantum mechanics has one of the strangest landscapes in science. It is the world atomic and sub-atomic particles. Yet it is also a field that holds great promise for better understanding the entire universe. One of the reasons that the field of quantum mechanics may provide the ultimate breakthrough to our understanding of how things work is that it is the gateway to quantum computing.
Because the qubit (i.e., the quantum bit) is the irreducible carrier of quantum information, it also requires the least amount of energy to control; hence, quantum computers hold the promise of small size, great speed, and efficient operation. It should come as no surprise that developing a commercial-grade quantum computer has become the Holy Grail of computing. Quentin Hardy reports that Lockheed Martin believes development of a reliable quantum computer has finally reached the point where it can be scaled for commercial use. [“A Strange Computer Promises Great Speed,” New York Times, 21 March 2013] Hardy reports:
“A powerful new type of computer that is about to be commercially deployed by a major American military contractor is taking computing into the strange, subatomic realm of quantum mechanics. In that infinitesimal neighborhood, common sense logic no longer seems to apply. A one can be a one, or it can be a one and a zero and everything in between — all at the same time. It sounds preposterous, particularly to those familiar with the yes/no world of conventional computing. But academic researchers and scientists at companies like Microsoft, I.B.M. and Hewlett-Packard have been working to develop quantum computers. Now, Lockheed Martin — which bought an early version of such a computer from the Canadian company D-Wave Systems two years ago — is confident enough in the technology to upgrade it to commercial scale, becoming the first company to use quantum computing as part of its business.”
The reason this is big news is because “to date, quantum computers have been implemented so that programming their operation was, in essence, hardwired into their essential structure. Although many useful demonstrations of quantum computing have resulted from such special-purpose devices, they are basically one-problem computers which cannot easily be reprogrammed or scaled to attack larger problems. As early models of practical quantum computers, they don’t make the grade.” [“Quantum computer with separate CPU and memory represents significant breakthrough,” by Brian Dodson, Gizmag, 12 February 2012] Because mastering quantum computing has proved to so difficult, Hardy reports, “Skeptics say that D-Wave has yet to prove to outside scientists that it has solved the myriad challenges involved in quantum computation.” Regardless of the skeptics, Ray Johnson, Lockheed’s chief technical officer, is a believer. He told Hardy, “This is a revolution not unlike the early days of computing. It is a transformation in the way computers are thought about.” He’ll be correct, if the D-Wave computer works as advertised.
Because of their potential for high-speed computation, quantum computers could tackle some of the world’s most difficult challenges. Lockheed Martin plans to use the D-Wave computer “to create and test complex radar, space and aircraft systems.” But Hardy notes that quantum computers are ideal for research in a number of fields including medicine and artificial intelligence. One of the reasons that there are vocal skeptics following the Lockheed Martin announcement is that in 2007 D-Wave announced it would have a commercially-available quantum computer within a year. The company had to withdraw that claim shortly after it was made. For more on the uproar that created back then, read my posts entitled Quantum Computing — Not Coming Soon to a Store Near You and Quantum Computing or Quackery? Hardy continues:
“People working in quantum computing are generally optimistic about breakthroughs to come. … Quantum computing has been a goal of researchers for more than three decades, but it has proved remarkably difficult to achieve. The idea has been to exploit a property of matter in a quantum state known as superposition, which makes it possible for the basic elements of a quantum computer, known as qubits, to hold a vast array of values simultaneously. There are a variety of ways scientists create the conditions needed to achieve superposition as well as a second quantum state known as entanglement, which are both necessary for quantum computing. Researchers have suspended ions in magnetic fields, trapped photons or manipulated phosphorus atoms in silicon.”
Last year, John Markoff reported, “Australian and American physicists have built a working transistor from a single phosphorus atom embedded in a silicon crystal.” [“Physicists Create a Working Transistor From a Single Atom,” New York Times, 19 February 2012] Andreas Heinrich, a physicist at IBM, told Markoff that “the research was a significant step toward making a functioning quantum computing system.” Gerhard Klimeck, a professor of electrical and computer engineering at Purdue, told Markoff, “It shows that Moore’s Law can be scaled toward atomic scales in silicon.” Markoff explains, “Moore’s Law refers to technology improvements by the semiconductor industry that have doubled the number of transistors on a silicon chip roughly every 18 months for the past half-century. That has led to accelerating increases in performance and declining prices.”
Catherine Zandonella reports that another breakthrough that has been made is that quibits are now able to be manipulated “at room temperature. Until recently, temperatures near absolute zero were required, but new diamond-based materials allow spin qubits to be operated on a table top, at room temperature.” [“Quantum computing moves forward,” Princeton Journal Watch, 7 March 2013] Hardy reports, “In the D-Wave system, a quantum computing processor, made from a lattice of tiny superconducting wires, is chilled close to absolute zero. It is then programmed by loading a set of mathematical equations into the lattice.” Obviously, a system that didn’t need to be chilled close to absolute zero would be a cheaper system to operate. A second big breakthrough, Zandonella reports, “is the ability to control these quantum bits, or qubits, for several seconds before they lapse into classical behavior. … A remaining challenge is to find ways to transmit quantum information over long distances.”
One of the more mysterious characteristics of quantum mechanics that affects quantum computing is entanglement. “Many quantum algorithms require that particles’ spins be ‘entangled,’ meaning that they’re all dependent on each other,” writes Larry Hardesty. “The more entanglement a physical system offers, the greater its computational power.” [“Proving quantum computers feasible,” MIT news, 27 November 2012] Hardesty continues:
“Until now, theoreticians have demonstrated the possibility of high entanglement only in a very complex spin chain, which would be difficult to realize experimentally. In simpler systems, the degree of entanglement appeared to be capped: Beyond a certain point, adding more particles to the chain didn’t seem to increase the entanglement. … However, in the journal Physical Review Letters, a group of researchers at MIT, IBM, Masaryk University in the Czech Republic, the Slovak Academy of Sciences and Northeastern University proved that even in simple spin chains, the degree of entanglement scales with the length of the chain. The research thus offers strong evidence that relatively simple quantum systems could offer considerable computational resources.”
Jacob Aron reports that “chips made by D-Wave … have passed two tests that suggest that the bits in their machines have the quantum property of entanglement. That doesn’t end the controversy, but it strengthens D-Wave’s claim that a revolution in computing is a lot closer than we thought.” [“Controversial quantum computer aces entanglement tests,” NewScientist, 8 March 2013] Whether the D-Wave computer proves out or not, breakthroughs continue to be made.
Joseph Brean reports, “Canadian researchers have succeeded in side-stepping an obstacle of Heisenberg’s Uncertainty Principle, a strange law of the quantum world that says precise measurement is impossible, because the act of measuring changes what you are trying to measure. Their experiment in an Ottawa lab — in which they measured the polarization states of single light particles, called photons — is seen as a small step toward a quantum computer, a major goal of modern science.” [“Canadian researchers take a sneak peek at Schrödinger’s Cat and a step toward a quantum computer,” National Post, 4 March 2013] A research team at Yale “recently developed a new way to change the quantum state of photons, the elementary particles researchers hope to use for quantum memory.” [“Yale Researchers Ride Photons in Search of Quantum Computer,” by Klint Finley, Wired, 29 March 2013] Science Daily reports, “Carbon nanotubes can be used as quantum bits for quantum computers. A study by physicists at the Technische Universitaet Muenchen (TUM) has shown how nanotubes can store information in the form of vibrations. Up to now, researchers have experimented primarily with electrically charged particles. Because nanomechanical devices are not charged, they are much less sensitive to electrical interference.” [“Quantum Computers Counting On Carbon Nanotubes,” 21 March 2013] “UCLA physicists have pioneered a new technique that combines two traditional atomic cooling technologies and brings normally springy molecules to a frozen standstill.” [“Quantum Computing? Physicists’ New Technique for Cooling Molecules May Be a Stepping Stone to Quantum Computing,” Science Daily, 27 March 2013] Finally, Adrian Cho reports:
“You’ve heard the hype a hundred times: Physicists hope to someday build a whiz-bang quantum computer that can solve problems that would overwhelm an ordinary computer. Now, four separate teams have taken a step toward achieving such ‘quantum speed-up’ by demonstrating a simpler, more limited form of quantum computing that, if it can be improved, might soon give classical computers a run for their money. But don’t get your hopes up for a full-fledged quantum computer. The gizmos may not be good for much beyond one particular calculation.” [“New Form of Quantum Computation Promises Showdown With Ordinary Computers,” Science, 21 December 2012]
With new breakthroughs being announced almost daily, if the world of quantum computing hasn’t already arrived with the D-Wave system, its development is likely in foreseeable future.