Violation of Bell’s inequality in Josephson phase qubits

Very cool…another step towards demonstrating that Josephson phase/flux systems can be treated as macroscopic coherent quantum objects.

Violation of Bell’s inequality in Josephson phase qubits

I was wondering if you could demonstrate this the other day!

From Science Daily:

The measurement of a Bell violation in a superconducting circuit was recently stated to be the next primary challenge for the superconducting qubit community, according to Martinis.

Martinis said: “This experiment has met this challenge, achieved by performing a very demanding measurement on a pair of Josephson qubits, a measurement that requires excellent control over qubit state preparation, qubit entanglement, and very high fidelity single-shot state measurements of the entangled qubits. It directly proves that quantum mechanics is the only possible description for the behavior of a macroscopic electrical circuit.”


Via The Quantum Pontiff:

What an AWESOME idea for a conference!

Coherence in Superconducting Qubits 2010


…I shouldn’t get so excited about these things, but, but… just look at the topic list! 😀

This conference will foster discussion and collaboration among investigators stimulating:

* A fuller, more accurate understanding of the types of defects limiting coherence in superconducting JJ qubits; including the mechanisms by which they occur, how they are created in fabrication, the mechanisms by which they affect and interact with the qubit, and the qubit performance characteristics they limit (coherence times T1 and T2, Rabi contrast, etc.),
* Development of advanced methods for definitive characterization and measurement of defects in the presence of other defects;
* Discovery of new low-defect materials and constructions, and the means for their fabrication;
* Understanding of ultimate, coherent qubit geometries begged by the physics, and the means for their fabrication.
* Improvements in electronics and systems enabling high-fidelity qubit control and measurement; and
* Enhanced scientific vision for the most effective means to substantially extend coherence

Ooooh, nice. Hope I can find the money for this. Singularity Summit 2009 might just have me bankrupt!

CMMP 2009

It’s that time again! The UK’s hottest low temperature conference…Condensed Matter and Materials Physics 2009. Venue: Warwick University.


Why not join me for some unmissable Physics action – just click on the link above to sign up. I’ll hopefully by then have some form of poster with results from measurements on Ferromagnetic Josephson Junctions. By the way the abstract deadline is in 2 days time…

World’s first on-chip quantum computer! Oh wait…

So I opened my freshly delivered copy of this month’s Physics World and began to mull over the articles whilst enjoying a Kitkat. On the first page I found an piece about Ion Trap quantum computing proclaiming that “Researchers in the US claim to have created the first small scale device that can perform all the steps needed for large-scale quantum computation” referring to NIST’s latest ion trap chip.

You can read about it here:
Scalable ion traps for quantum information processing

Here is the PhysicsWorld web version of the article:
Tiny device is first complete ‘quantum computer’

Haven’t superconducting flux/charge qubits have been able to do this for ages – what’s all this ‘first’ business? Besides, didn’t Yale do something similar a few months back? Oh no, wait a minute, they actually ran an algorithm…
And that’s without even considering the advances in AQC, hmmm.

Anyway, that didn’t bother me too much. But then the article goes on to say:

“The implication was that quantum computers could operate at ultra-high speeds, which could be applied to solving complex problems like cracking some of today’s most widely used encryption codes.”

Is that the BEST application you can think of to run on a QC? Really? Come on… Get creative! Who cares about cracking RSA anyway? They’ll just keep adding more digits 😉

In fairness the magazine also had quite a nice article about the violation of Bell’s inequalities and some of the potential loopholes in those experiments. Which made me happier.