Quantum computers have captured the attention of the computer science world because they are faster than classical computers for some problems. Spend any time reading about quantum computing technology, and you’ll see that statement over and over again. But what does it actually mean, given that classical computing is a mature, highly optimized technology and quantum computers are in their infancy?The phrase “quantum speedup” is used to describe a wide range of situations, in which the advantage quantum computers offer might be quite large, relatively small, or nonexistent. At one extreme, we find “strong” quantum computing algorithms. These are the algorithms that started it all, that convinced the community that quantum computing was worth pursuing. Grover’s search algorithm, for example, is provably faster than any known or potential classical search algorithm. In the best classical search algorithms, the time required grows at the same rate as … [Read more...] about How To Program A Quantum Computer
Adiabatic quantum computer
Quantum Computing Breakthrough
An earlier series of articles on quantum computing discussed the differences between the gate logic model and the quantum annealing model. The gate logic model, like transistor logic, uses a limited number of “gates” to construct a general purpose computer, theoretically capable of solving any problem for which a suitable algorithm can be found. In systems designed around the gate logic model, noise from a variety of sources is a significant issue. Complex error correction mechanisms are needed to preserve the system state for the duration of the calculation.In the quantum annealing model, in contrast, the calculation takes place through adiabatic evolution of the system from the original “problem” state to an optimal “solution” state. A quantum annealer models the problem to be solved as an Ising glass, a system of interacting spins. Adiabatic evolution maintains the system in the ground state, so it is less vulnerable to noise than a gate logic … [Read more...] about Quantum Computing Breakthrough

DWave’s Year of Computing Dangerously
Editor’s Picks Physicists Build First SingleAtom Quantum Bit in Silicon Do You Need a Quantum Computer to Achieve Machine Consciousness? Quantum Bit Stored for Record 39 Minutes at Room Temperature When in 1935 physicist Erwin Schrödinger proposed his thought experiment involving a cat that could be both dead and alive, he could have been talking about DWave Systems. The Canadian startup is the maker of what it claims is the world’s first commercialscale quantum computer. But exactly what its computer … [Read more...] about DWave’s Year of Computing Dangerously
Will Silicon Save Quantum Computing?
Grand engineering challenges often require an epic level of patience. That’s certainly true for quantum computing. For a good 20 years now, we’ve known that quantum computers could, in principle, be staggeringly powerful, taking just a few minutes to work out problems that would take an ordinary computer longer than the age of the universe to solve. But the effort to build such machines has barely crossed the starting line. In fact, we’re still trying to identify the best materials for the job. Today, the leading contenders are all quite exotic: There are superconducting circuits printed from materials such as aluminum and cooled to onehundredth of a degree above absolute zero, floating ions that are made to hover above chips and are interrogated with lasers, and atoms such as nitrogen trapped in diamond matrices. These have been used to create modest demonstration systems that employ fewer than a dozen quantum bits to factor small numbers or simulate some of the … [Read more...] about Will Silicon Save Quantum Computing?
Loser: DWave Does Not Quantum Compute
This is part of IEEE Spectrum's special report: Winners & Losers VII DWave Systems, a Canadian startup, recently booted up a custombuilt, multimilliondollar, liquidheliumcooled beast of a computer that it says runs on quantum mechanics. That's right. DWave, a 55person company operating out of an office park in Burnaby, B.C., claims to have built that almost mythical machine, that holy grail of computing, the stuff of scifi novels and technothrillers—the quantum computer. Such a system would exploit the bizarre physics that apply on ridiculously small scales to compute ridiculously fast, solving problems that could stymie today's supercomputers for the lifetime of the universe. Now, building a practical quantum computer has proved hard. Really hard. Despite efforts by some of the world's top physicists and engineers and the likes of IBM, HP, and NEC, progress has been slow. Ask the experts and they'll tell you these systems are a decade—or five—away. … [Read more...] about Loser: DWave Does Not Quantum Compute
Quantum Computing Experiment Adds “Control Knob” for DWave Machine
DWave's claim to having built the world's first commercial quantum computers depends upon the workings of heliumcooled machines chilled to just 20 millikelvin (273 degrees C).That frigid temperature is necessary to prevent thermal "noise" from overwhelming any quantum effects that might be present in the machines. But now researchers have come up with a "tunable noise knob" that allows them to collect a wider range of experimental data to test whether DWave's machines actually harness the spooky effects of quantum mechanics in their computing processes. Their recent paper titled "Distinguishing Classical and Quantum Models for the DWave Device" is the latest to weigh in on the raging controversy about whether DWave's machines actually perform quantum computing. Several groups of researchers independent of DWave have presented evidence on both sides of the debate by comparing experimental results from DWave machines with models of classical computing and quantum … [Read more...] about Quantum Computing Experiment Adds “Control Knob” for DWave Machine
New Computer Combines Electronic Circuits with Light Pulses
Modern computers still lack the capability to find the best solution for the classic “traveling salesman” problem. Even finding approximate solutions is challenging. But finding the shortest traveling salesman route among many different cities is more than just an academic exercise. This class of problems lies at the heart of many realworld business challenges such as scheduling delivery truck routes or discovering new pharmaceutical drugs. Today ’s computers handle combinatorial optimization problems by skipping some of the weaker solutions instead of considering all possibilities to find the very best solution. But U.S. and Japanese researchers have unveiled a new specialized computer that could someday solve the traveling salesman scenario and similar problems more efficiently. Their hybrid machine combines digital electronic circuits with optical devices similar to lasers. … [Read more...] about New Computer Combines Electronic Circuits with Light Pulses
PROTOTYPE COMMERCIAL QUANTUM COMPUTER DEMO’ED
A Vancouver startup, DWave Systems, claims to have demonstrated the world's first commercially viable quantum computer. They were quite confident of this, considering that their press release trumpeted a success at least ten minutes before the demonstration was scheduled to begin at the Computer History Museum in Mountain View, Calif. They've certainly reason to be confident. Even though a quantum computer is commonly considered a research affair that's as much as 20 years away from usefulness, DWave not only formed a company to develop a unit but also got venture capitalists to fund it. They picked up US $14 million last May. Today, the company was supposed to show off a quantum computer sporting 16qubits, the most of any quantum computer, commercial or otherwise, but still way too few to do anything important. What's a qubit? Qubits, or quantum bits, are what make quantum computers different from their digital ancestors. A digital bit can be either a one or a zero but not both … [Read more...] about PROTOTYPE COMMERCIAL QUANTUM COMPUTER DEMO’ED
Upgrading the Quantum Computer: New Architecture makes Implementation Scalable
HPC All current approaches for adiabatic quantum computation face the same challenge: The problem is encoded in the interaction between qubits; to encode a generic problem, an alltoall connectivity is necessary, but the locality of the physical quantum bits limits the available interactions. "The programming language of these systems is the individual interaction between each physical qubit. The possible input is determined by the hardware. This means that all these approaches face a fundamental challenge when trying to build a fully programmable quantum computer," explains Wolfgang Lechner from the Institute for Quantum Optics and Quantum Information (IQOQI) at the Austrian Academy of Sciences in Innsbruck.Fully programmable quantum computerTheoretical physicists Wolfang Lechner, Philipp Hauke and Peter Zoller have proposed a completely new approach. The trio, working at the University of Innsbruck and the IQOQI, suggest overcoming the challenges by detaching the logical qubit from … [Read more...] about Upgrading the Quantum Computer: New Architecture makes Implementation Scalable
Google May Give Quantum Computing a Job in Search
Google is looking at quantum computing to help it sort through the millions of searches it conducts daily, and it's working with processors from Canadian company DWave.Quantum computing will help Google with the sophisticated artificial intelligence technologies such as machine learning and pattern recognition that its services are based on.Solving the more difficult problems inherent in machine learning and pattern recognition using more conventional methods would require server farms so large that they could never realistically be built, wrote Harmut Neven, Google's technical lead manager of image recognition, on Google's research blog. Instead, quantum computing may hold the key.Quantum computers make direct use of phenomena in quantum mechanics, such as superposition and entanglement, to work on data. The idea is that quantum properties can be used to represent data and to perform operations on these data.Quantum superposition, which defines the collection of all possible states … [Read more...] about Google May Give Quantum Computing a Job in Search