What’s the deal with Google’s quantum computer?

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Google and NASA Team Up on Quantum Computer

The next generation of computers is a few years off, but it’s pretty damn cool

For The Daily Beast:

It’s like no computer you’ve ever seen, nor are you likely to ever own. It promises speed and the ability to tackle problems ordinary computers can’t handle.

The machine is the D-Wave 2X, and the only working model outside the company is in the Quantum Artificial Intelligence Lab. A joint project between Google, NASA, and the Universities Space Research Association, the lab will test-drive the 2X on some sticky problems in high-powered computing.

The 2X is a type of quantum computer, which means it uses devices that exploit quantum physics to replace transistors and other components of ordinary computers. The quantum nature of the inner workings in theory should make the computer solve problems much faster than anything else available, making it useful for a wide range of applications. While there are no fully quantum computers out yet, the 2X is the closest yet—assuming it works as advertised. [Read the rest at The Daily Beast…]

Two weeks in review (September 29 – October 12, 2013)

The center of the Milky Way lies at the upper left of this image from the 2MASS survey of galaxies. [Credit: 2MASS/G. Kopan, R. Hurt]

My black holes class and other responsibilities ate my brain the last two weeks, so I forgot to post a “week in review” last week. So, here’s the highlights from the last two weeks. If it’s more heavily weighted toward black holes even than usual, that’s hardly surprising.

  • Of fire and ice and Harlow Shapley (Galileo’s Pendulum): In 1918, a poet named Robert Frost met an astronomer named Harlow Shapley. The result, according to Shapley, was “Fire and Ice”. Most people probably don’t remember who Shapley was anymore, but in his day he was one of the most prominent astronomers, helping to map the galaxy and measuring its size.
  • Portrait of a black hole, part 1 (Galileo’s Pendulum): When trying to understand the curved four-dimensional spacetime of gravity, we have to resort to metaphor and simplified pictures. Here’s my attempt to describe spacetime around a (non-rotating) black hole using a dynamic analogy: a flowing current, against which objects must move.
  • A scientific love affair (Galileo’s Pendulum): Like many (most?) little kids, dinosaurs captured my imagination, sparking me to think about science for the first time. However, black holes, pulsars, and other products of extreme gravity inspired me in a different direction when I was in sixth grade. Here’s a partial story of my love affair with gravity.
  • The 2013 Nobel Prize in physics: the Higgs boson (Galileo’s Pendulum): The 2013 Nobel Prize was awarded this week to François Englert and Peter Higgs for the theoretical prediction of what is now known as the Higgs boson. This post celebrates that award, but also delves into how the Nobel Prize fails. In promoting the “lone (male) genius” view of science and thereby failing to acknowledge contributions by the others who deserve recognition for the Higgs boson, the Nobel Prize does a disservice to that which it seeks to honor. Bonus: what the Nobel Prize has to do with the leg lamp from A Christmas Story.
  • Measuring a superconducting qubit by manipulating its environment (Ars Technica): Now for something completely different! Quantum systems are complicated, involving interactions between the objects we want to study, the environment of those objects, and our measuring apparatus. A new experiment shows a way of measuring an object’s properties indirectly by performing environmental measurements instead. The result is a picture of a superconducting quantum bit (or qubit) as it evolves in time.

Often in physics, we can separate the object from the environment and the experimental apparatus from what’s being measured, but that separation is approximate. In quantum systems, those distinctions break down, to the point where the environment “measures” the system, in ways we don’t fully understand even after nearly a century of study. (A lot of nonsense has been written about the subject, too, which is a rant for another day.) A new experiment may help mitigate some of the problems of system-environment interaction, through understanding how photons and atoms couple—and when they do not.

One remaining frontier is comprehension of how systems gradually lose coherence via interactions with their environment, which prevents their usefulness in quantum computing. A new set of experiments by Yinnon Glickman, Shlomi Kotler, Nitzan Akerman, and Roee Ozeri revealed part of the mechanism by which environment disrupts quantum systems: photons. They found that photons that interacted with a quantum system can end up correlated with the system’s state, the hallmark of entanglement. By careful preparation of the atom’s state, it may be possible to reduce the loss of quantum information to the environment, and thus extend the life of these systems. [Read more…]

Disentangling environmental influences in photon-atom interactions

Information in quantum physics is carried in a system’s quantum state, which is basically a list of all the important properties. An atom’s state, for example, contains the relative orientation of the nucleus and electrons, the energy levels the electrons occupy, and the like. Quantum computing manipulates these states in prescribed ways for calculation purposes, but to get the data from one place to another requires communication:

W. J. Munro, A. M. Stephens, S. J. Devitt, K. A. Harrison, and Kae Nemoto have designed a system where quantum bits (qubits) were transferred by individual photons, but interpreted using a special algorithm designed to contain a lot of redundancy and avoid data loss. Since the states of the transmitter and receiver were not entangled (or copied), they don’t need to remain coherent, obviating the need for quantum memory. The actual data transfer could take place over fiber optic cables, and the receiver could itself be used as a transmitter, forming a repeater for larger networks. [Read more….]

Quantum communication without entanglement

I’m currently in San Francisco for my younger brother’s wedding, but that doesn’t stop me from providing science content to you, dear readers. (Ahem.) Researchers have figured out a way to read and manipulate the quantum spin state of a single electron—a classic example in quantum computing that up until now has existed only in theoretical calculations.

By embedding a phosphorous atom in silicon, the researchers used this contrast to isolate the properties of a single electron orbiting the atom. They massaged the electron spin into a particular state using microwaves to drive the system. Varying the microwave pulses, the researchers could cause the electron spin to flip in a controlled fashion. [Read more….]

Building quantum computations from a single electron spin