One of the big pushes occuring in ion trap quantum computing these days is the construction of different ion traps which will be useful in scaling up these quantum computer architectures. Chris Monroe’s group at Michigan (in collaboration with Keith Schwab at the PRL in Maryland) has a nice paper out a few days ago in Nature Physics describing a new ion trap they have built (for a news release, see here. ) This microtrap is built, basically, on a semiconductor chip, and is of the micrometer size as compared to the millimeter sized traps normally used for trapping ions. Because these traps are fabricated using semiconductor MEMS technology, it is not unreasonable to think of building traps which can stored hundreds to thousands of ions at a time.
One interesting property of the traps described in the paper is the shallow depth of the trapping potential as compared to the depth of the potential for larger, milimeter scale traps (about 0.08 eV in the former compared to order 1 eV in the latter.) What this means is that the ions they trap stay in the trap for minutes as opposed to days, and that it has not been possible to simultaneously trap two ions in the trap. Which is what I love about experiments: while this is an important step, we’re certain to see more steps in the future and it is not unreasonable to expect some good scaling up in of ion trap quantum computers in the next few years.
Another set of experiments involving traps designed to be scalable comes from Isaac Chuang’s group at MIT. A preprint of their work is available as quant-ph/0511018. Me, I just like to flip to the end of their paper and stare at their neat hexagonal trap and dream of the cool things I could do with such a trap.
O brave new quantum world!
A nice step. Does the chip still have to be in a vacuum, or loaded by a MOT or somesuch? If so its still not a “chip” as most common folk think of them. But its still a great step, and Monroe’s group continues to be at the forefront!
I believe the chip is in vacuum and loading is not done by a MOT, but simply by ionizing the ions in the trapping region. At least that’s how I understand it, but what do I know I’m a crazy theorist.
Well I’m a crazy theorist too. If they get the ions in-situ that is a step forward
ionizing the ions… cool ;p
err ionizing the atoms. doh!
David,
I asked Anthony Acguirre this question, but I’m curious what you think? If Acquirre is right and “[t]he productive strategy . . . seems to be one of accepting multiverses as a possibility, and working toward understanding how to calculate the various ingredients necessary to make predictions in one,” do you think it will be possible, assuming a sufficiently isolated, cluster ion trap quantum computer connected by flying photons (distributed matter qubits coupled by optical methods) of say 50 qubits, to design useful experiments that would only be valid in some predictable number multiple universes?
Well I have to say I don’t understand all this “multiverse” stuff. Often this is because the word multiverse is used by lots of different people in lots of different ways. But mostly its because I talk to too many experimentalists and so, while I find speculation interesting, what we know and what we expect hasn’t got much to do with the ideas of a multiverse.
On way the idea of a “multiverse” is used to describe alternative “branches” in a many-worlds theory. From this point of view, in order to get “access” to the other universes, as far as I can tell, you will need to modify quantum theory. Now this may turn out to be correct, but it is an extremely radical notion. I don’t know if there are suprises coming when we build a large scale quantum computer, but everything I do know suggests otherwise. From Scott Aaronson and John Preskill I’ve learned that it is extremely difficult to modify quantum theory in a manner which is innocuous (i.e. which does not allow for faster than light communication or the rapid solution of intractable problems, thus rendering the idea of science nearly mute.) So, while in my own dreams I like to think radical thoughts, as a physicist, I will tell you what we know today, and what we know today doesn’t suggest any possibility of testing whether the ideas of “multiverses” are correct or not.